#precalculus

1 messages Ā· Page 37 of 1

whole perch
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they think im those comp math nerds

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whats ur GPA

tranquil inlet
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4.0 straight a's but physically cannot take ap classes (in freshamn)

whole perch
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oh

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no honors?

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or is that unweightes

tranquil inlet
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our school doesnt weight honors

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😭

whole perch
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oof

tranquil inlet
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what aps u taking next year

whole perch
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ap calc ab/bc (im gonna request to change my course load to ap calc ab and ap pysc instead tho), ap us gov, ap csp

tranquil inlet
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i see

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im taking ap chem, ap calc, and ap cs

whole perch
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how ap chem?

tranquil inlet
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its what all the sophomores take

whole perch
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oh they only let us take normal chem

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or honors

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im taking honors

tranquil inlet
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nah my school u can take regular honors or ap chem but if u fck up, u fck up

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taking summer school honors chem tho

whole perch
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oh

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alr bro im sleepy af

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cya

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gl

tranquil inlet
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ok bye

whole perch
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with life

tranquil inlet
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you 2

whole perch
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bye

tranquil inlet
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byee

hallow lodge
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how is -2.087 greater than 0.05

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is it going by the graph

pure sable
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hiii can someone help me?

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pleaseee

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how would i graph this if the radius has a square root?

fiery creek
pure sable
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graph circle

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i think i figured it out i just have to approximate

fiery creek
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are you graphing a circle at center (4, 1) with radius 2 sqrt(2)?

fiery creek
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you would graph it the same way as anything else

pure sable
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ohhhh ok

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thank you šŸ™‚

fiery creek
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except it's kinda pointless to do it by hand since there won't be much accuracy

fiery creek
pure sable
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or else she’ll give me a 0

fiery creek
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your teacher?

willow bear
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so at least you can get those exactly

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and eyeball the rest

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2 sqrt(2) is a little bit less than 3

pure sable
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no graph no credit

compact spade
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How would I go about doing these

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I can solve 11-18 but not 5-10

proven void
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  1. C(3,1)
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no?

proven void
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why precalculus?

compact spade
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Could I uh

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Get some help with these

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Still a little lost :(

jovial coral
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Sure let me read them

compact spade
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Thank you 😭

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I need to go to bed I have a sleep schedule to fix

proven void
jovial coral
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Lemme see

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Yes I think so

proven void
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doesnt make any sense that the order matters

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c(1,8)

proven void
jovial coral
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Yes

proven void
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7 is combi, c(1,3) aswell

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order doesnt matter

jovial coral
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I need to go to sleep. Sorry I couldn't help more. gn

proven void
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gn sleep well scraxzt

compact spade
jovial coral
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Thanks

compact spade
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@willow bear I'm sorry for pinging you - if you'd prefer that I don't just lmk and I won't do it again but I'm so lost on this hw, I need to go to bed, and I really, really need help

willow bear
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which one(s)

compact spade
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5-10

willow bear
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these?

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ok, do you have progress on any one of these? if you do, share your progress and we'll start with that. otherwise we will go through them in order.

compact spade
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I mean, I know the functions for permutations and combinations

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I know that permutations means order matters

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I just don't know how to determine which is which

willow bear
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im talking about these specific problems -- do you or do you not have progress on at least one of them?

compact spade
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No, I don't

willow bear
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ok

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for some of these you dont need to know permutations/combinations and just need to know shit like the multiplication principle

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which may go by many names or none at all

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but let me give you a different setup as an example

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have you ever seen, or held in your hands, a deck of cards? @compact spade

compact spade
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Yes

willow bear
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like regular poker cards

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ok

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so you know that the cards come in 4 suits and within each suit there are 13 ranks

compact spade
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Yes

willow bear
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and there's exactly one card for each suit-rank combination

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for a total of 4 * 13 = 52 cards

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the same principle applies to problem 5, in which you choose from 3 different albums and 2 different formats (the choice counts being independent of each other)

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do you see what i'm talking about here?

compact spade
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Yes!

willow bear
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ok great

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problems 5, 6, 8 and 10 can be done with this method more or less directly

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we'll come back to 7 and 9 in a moment

compact spade
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Ok, perfect

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Thank you so much

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I'll let you know when I'm onto 7 & 9

willow bear
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ok sure

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you can ping me when that happens

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(but you will have to remind me cause i might forget this)

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(like just tell me the problems you're following up on or w/e)

compact spade
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Onto 9! We can do 7 also but I figured that one out by just writing them down

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@willow bear

willow bear
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alright

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so for 7 you can also apply the multiplication principle in a similar way

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carlos has:

  • 3 subjects to choose from as his first
  • 2 subjects to choose from as his second (because one has already been done as the first)
  • 1 subject to choose from as his last
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for 3 * 2 * 1 = 3! = 6 ways

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for 9 proceed in a similar fashion but place the dictionary first

compact spade
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ohhhhhh ok

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that's really easy thank you

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can i like

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pay you??

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you've helped me with my math homework like 5 times now and i feel like i should do something back idk

willow bear
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i mean uh

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all the shit i do on here i do pro bono

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if any money were to change hands we would not want to do it on here bc rules

compact spade
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that's true

dense coyote
willow bear
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sorry for replying to this message
could have just pinged me

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anyway all toughness is relative

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so i cant answer that

viscid thistle
dense coyote
dense coyote
quiet bane
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Hi

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Is anyone here good at sequences

winter comet
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you should prob just post ur problem tho

quiet bane
winter comet
quiet bane
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Here

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And in disscution / prealg / geometry

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The problem is that the exercise isn't that hard

winter comet
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and uh yeah i dont know series that well

fallow field
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Is anyone free to help me study chapter 3

3.1 to 3.5. I have a study guide.

hushed sphinx
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You still haven't told anyone which book.

fallow field
coarse ginkgo
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Can someone please help me visualize this. I’m not sure if i did it correctly

obsidian monolithBOT
white rapids
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Shouldnt the x value be 4 since the original is 8?

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I did the graph on desmos, but graph g seems to be compressed

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Someone explain pls

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Nvm

shut monolith
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this would be a correct visualization (im taking the lighthouse to be a single point as we don’t know about any internal details regarding the lighthouse at all)

viscid thistle
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Hey y'all, I don't take pre-calc, but I am currently teaching myself as it was something that I "skipped" over. I have had mixed opinions on skipping pre-calc and going straight to calc 1. Looking for some opinions here, anything is appreciated!

whole perch
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yo i was using my calculator on the test

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and it said -1^2

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was -1

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am i buggin

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or what

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how

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shouldn'[t it be 1

river drift
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by convention, we define the order of operations to say that
[ -1^2 = -(1^2) \ne (-1)^2 ]

obsidian monolithBOT
whole perch
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oh

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shit

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iok

worn bridge
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HOW DO I TRANSLATE THIS to summation notation
If i had a penny that doubled each time per day, how many would i get in 30 days

echo sinew
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This is the closed formula

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In your case it's 1•(1 - 2^31)/(1-2), which is 2³¹ - 1

willow bear
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but also as-written it doesn't suggest that sum

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we have a magical penny that clones itself every night, not a money machine that starts out paying you a penny a day and then pays twice as much every day as it did the last

echo sinew
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Oh you're right, I must have misread it

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Then prolly the answer they want is 2³⁰

daring tapir
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am i just too dumb or should the answer he wants be 2^29 instead?

willow bear
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the problem is stated too vaguely

daring tapir
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true

worn bridge
willow bear
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you yourself said the question is made up by you.

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"summation notation" is not a panacea, and is not a thing you should be trying to shoehorn into every single problem you see or think of

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anyway, with this more precise statement, your penny undergoes 29 doublings, so you end up with 2^29 = 536870912 pennies, or $5,368,709.12 at the end of it.

hallow lodge
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i need help with factoring

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like literally simple factoring

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how do u do it

willow bear
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first hit on youtube search for "ochem tutor simple factoring"

hallow lodge
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yt videos js show the factored function automatically

willow bear
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do you have a particular problem or problems that you are having a hard time with?

hallow lodge
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could u tell me the formula for it

willow bear
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  1. avoiding the question
  2. there is no "formula"
hallow lodge
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having problem with it in general

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what abt the steps

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ive been having problems with factoring since 1st sem

uncut mulch
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post specific problems you have an issue with

winter comet
# hallow lodge what abt the steps

4x^2 + 8x
= 2 * 2* x * x + 2 * 2 * 2 * x
you're multiplying all these factors, if you are adding two terms then you can take common factors out of the two terms
you can see that both terms have two 2s and one x in common, so you can "factor" these out of both terms.
you can take out, 2 * 2 * x, and the remainder is (x + 2)
so, it equals
2 * 2 * x * (x+2)
= 4x(x+2)
this ^ is the factored form, because it took all the common factors in each term out, and now you're multiplying by whatevers left

tranquil inlet
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How would I set this up to prove with induction

shut monolith
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are you proving for all numbers {0,1,2,3,…} or {1,2,3,4,…}?

hushed sphinx
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Divide into cases according to whether n is 3k or 3k+1 or 3k-1 for some k.

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Oops, didn't see you wanted induction.

worn bridge
# hallow lodge i need help with factoring

There is no formula, but, thetre is a first step to factkring which is takibg the gcf of all terms, so say, 4x+2x has (2x) as the gcf, so if you ffactor it, you will get 2x(2+1) basically you reverse foil method

tranquil inlet
shut monolith
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The question asks to ā€œprove n^3 + 2n is divisible by 3ā€, but it’s not clear what ā€œnā€ is

hushed sphinx
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It's true for all n in Z.

pure sable
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hi can someone help me because i wasn’t here for math today

shut monolith
pure sable
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what is foci?

shut monolith
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so the center, vertices, covertices, and foci (plural for focus) are all points, so your answer for each of them will be ordered pairs

i gtg sorry someone else should be able to explain hopefully

pure sable
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ur good thanks

golden cairn
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How do I solve this? I have been trying for like 30 minutes but I don’t even know

golden cairn
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I already did

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What do I do after I get: (3x)log6=(2x-3)log2

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I tried dividing by log 6 on both sides but I don’t know

winter comet
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yes, you can do that

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remember log6 and log2 are both just constants

golden cairn
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Ok

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Then what do I do after that?

winter comet
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factor it out

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it might have been better if you divided by log2 instead but what ur doing works as well

golden cairn
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Factor what out?

winter comet
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sorry i meant distribute šŸ’€

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i don't know why i say factor instead of distribute šŸ’€

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i can't think of the word distribute lol

shut monolith
pure sable
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no but i still need help with this problem

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like how to graph vertices if one is a square root

shut monolith
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since the instructions just say ā€œsketchā€, you should be fine to estimate, just treat sqrt(12) like it’s 3.5, since that’s what it is approximately

stiff kelp
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u need help

winter comet
finite root
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Can you help me with this?

winter comet
finite root
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yes

winter comet
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can you write it out?

finite root
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cosacosB-sinasinB

willow bear
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ok, so make a table:

\begin{tabular}{r||c|c}
&$\alpha$&$\beta$\
\hline\hline
cos & & \
\hline
sin & &
\end{tabular}

obsidian monolithBOT
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|Ann⟩

willow bear
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fill it out based on the given data

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bc you're gonna need all four numbers in it to find cos(α) cos(β) - sin(α) sin(β)

devout bison
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oh ik it

willow bear
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@devout bison so you want someone to give you a worksheet of basic summation notation problems?

devout bison
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?

willow bear
willow bear
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you said you wanted some summation questions to practice, right?

devout bison
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a is alpha b is betha

willow bear
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beta, not betha.

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anyway ok gimme a couple more minutes.

devout bison
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okay thx by the way

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ig ik precalculus by the way

silent oasis
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while finding the limit by direct substitution how does b/0 (where b≠0) denote an asymptote?

willow bear
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@devout bison here you go

willow bear
silent oasis
devout bison
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when k/x xgoes to infinity y goes to 0

willow skiff
willow skiff
willow skiff
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it's just that it doesn't have to be one, it depends on the functions

willow skiff
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the green one is like y = 1/x around x = 0

willow bear
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@devout bison if you want you can DM me your work for any of these problems in the worksheet, but with two rules:

  1. include the questions themselves in your DM.
  2. show work and not only answers. i won't accept answers without work, even if they are right.
devout bison
willow bear
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define quick?

devout bison
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yeah kinda

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instead of going long

willow bear
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quick compared to what?

devout bison
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1 +4+9 etc

willow bear
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the sum in 1b) has length 4. i want you to do it longhand.

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i have even instructed you as such.

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also look more carefully at the notation.

silent oasis
willow skiff
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np

willow bear
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@devout bison i made the sums in Q1 short on purpose, so that working them out in some kind of "smart" way would take more effort than just doing as i instructed.

devout bison
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okay

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q2 is 1 ig

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q1)a)70

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the number on the up means that u will go as much as that or until that

willow bear
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work, not only answers.

devout bison
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or until that

devout bison
willow bear
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you have to write out your work properly and show it

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until then i will not accept any answers.

devout bison
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i dont have a phone am on pc not sure if cam will see it

willow bear
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my problems, my rules.

willow bear
devout bison
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at all

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i broke it last time

willow bear
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bruh ok

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well, you're gonna have to figure out how to write it nicely.

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cause im still not gonna accept answers without work.

devout bison
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@willow bear

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a quick method

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wait

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exactly like the graphics right

willow bear
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idk what you mean by "the graphics"

devout bison
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but we only take complete numbers here

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and thats a big problem

willow bear
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that explains precisely nothing...

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idk what on earth you are trying to say there sorry

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are you trying to ask me something, or are you trying to bounce an idea off of me?

devout bison
willow bear
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all 4 questions?

devout bison
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no just a method for all summations

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especially 4th

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1 and 3 were the same and method written

willow bear
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you want a panacea

devout bison
#

?

willow bear
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what you're asking me for is a "solve everything" method

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such a method does not exist

devout bison
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solve every summation

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?

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for example in functions there is

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1 method we apply to find areal of all these

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okay so how will 4th be

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@willow skiff

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<@&286206848099549185>

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@willow bear

devout bison
willow bear
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work out the first few terms, and see if you notice a pattern.

devout bison
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nope there wasnt

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i did all

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except for

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1)c)

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and 4th

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@everyone do u know a certain method to find out summation

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a method that could be applied for all summations

willow bear
willow bear
# devout bison nope there wasnt

ok then write out the first 8 terms of the summation $\sum_{k=0}^{85} \cos(k\pi/2)$ right here and now. not their sum, but the first 8 terms themselves.

obsidian monolithBOT
#

|Ann⟩

devout bison
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0 1 2 3 45 6 7 8

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cos0

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cos90

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oh i see

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it is cos90k

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which is either 0 0r 1 0r -1

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and they keep on each other

willow bear
devout bison
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4)17 ig

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thanks to the Almighty

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and what about 1)c

willow bear
devout bison
willow bear
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(for future answers that you don't give work for, i will simply say "no work" no matter if you get it right or not.)

willow bear
devout bison
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i worked in my mind

willow bear
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not acceptable.

devout bison
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why to write down on paper

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by the way u won't even see what i write

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and

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yeah i see

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it was wrong

willow bear
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make a word document and write your work there. it has an equation editor.

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and send screenshots of that.

devout bison
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the answer is

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1

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on 4th

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it is 1

willow bear
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answers without working are not accepted.

devout bison
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they roll into same after4th number

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and when we reach 85th

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they rolled

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but one still left and that is 85pi*k/2=1

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oh wait

willow bear
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you are expressing yourself poorly.

devout bison
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that is 0 either

willow bear
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what is your native language?

devout bison
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what u have as a knowledge doesnt give u the right of boasting on others because

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nothing we have is actually gained by our own

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it is a gift

willow bear
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i am not boasting on anybody.

devout bison
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but u kinda acted rude on me

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3 times

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just how old r u

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i am 16

willow bear
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"you are expressing yourself poorly" is the most polite way i know to convey that point.

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i am 24, if that matters at all.

devout bison
#

yeah it matters becuz at that age don't u think it is more impolite to insult someone smaller than u

willow bear
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i am not insulting you.

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or you could tell me what i said that you took as an insult.

devout bison
#

ok sorry then for misunderstanding

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yeah

willow bear
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ok, then what was it?

devout bison
willow bear
#

and what are the other 2 messages which you took as rude?

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you said there were 3

devout bison
devout bison
willow bear
#

ok, so maybe i should have suggested the alternative of "make a word doc and type shit there with equation editor" then and there.

devout bison
#

yeah

willow bear
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and i honestly don't see how "my problems, my rules" is rude. these are my problems that i made -- and i get to dictate what i want to see in response to them.

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if you don't like that, you don't have to do my problems.

devout bison
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then can u say like

willow bear
#

i am not forcing you.

devout bison
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i wanna see how uu do it

willow bear
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you want me to see how i do #4?

devout bison
#

yeah

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no

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i did 4th

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i only need a way for 3)c and and 1)c

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by the way i already did 4th and explained the way i did upwards

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i wanna see how uu do it- i typed it that u could talk like that since it is kinda more soft u see

willow bear
#

for 1c, just as for 1a and 1b, write the thing out longhand. it is only 5 terms.

devout bison
#

okay

willow bear
#

i am still interested in knowing what your native language is

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there is a chance we can communicate better in your language

devout bison
#

well it is turkish

willow bear
#

ok, nevermind

devout bison
#

okay

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yours is probably french ig?

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or german

willow bear
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no, my native language is Russian.

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anyway here is 1c

devout bison
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yeah but what about a quick method

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for all equations in the universe

willow bear
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such a method does not exist

devout bison
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not equations but summations i wanted to say

willow bear
#

and still

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such a method does not exist

devout bison
#

ups

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okay so

willow bear
#

for 3c, my first step would be to split the summation like this: $$\sum_{n=0}^{15} n^2 + \sum_{n=0}^{15} 6n,$$ and also realize you can replace the starting index 0 with 1 in both summations (because $6\cdot 0=0$ and $0^2=0$)

obsidian monolithBOT
#

|Ann⟩

devout bison
#

ohwait sorry

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i mistyped

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i don't need 3c

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okay i did all

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now i wanna ask u some questions

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did u know something so called e^ix=cos (x)+i*sin(x)

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what is the provement of this

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?

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@willow skiff @willow bear <@&286206848099549185>

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i mean where did it come from

willow bear
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the word is "proof", not "provement"

willow bear
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it is 200 times more rude than anything i have done.

devout bison
#

okay

willow bear
#

anyway

devout bison
#

so

willow bear
#

one idea you could think about is that if you look at the function f(x) = cos(x) + i sin(x) [where we don't know what e^ix should mean yet], it satisfies the law f(x+y) = f(x) * f(y)

#

so it should behave like an exponential function, i.e. e^(kx) for some constant k

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(because all exponential functions satisfy the same law)

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if you take the derivative of our function, you will find f'(x) = -sin(x) + i cos(x) = i*f(x)

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while the derivative of e^(kx) is k e^(kx), so k is the ratio of the function's derivative to itself

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in our case this ratio will be i, so our function could be written as e^(ix)

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(this is not rigorous. this is meant as one possible kind of intuition for euler's formula.)

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(to make a fully rigorous proof, we would need to dig into the definitions of e^z, sin(z) and cos(z).)

devout bison
#

? my question

willow bear
#

what?

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you asked about e^ix = cos(x) + i sin(x)

devout bison
#

yes

willow bear
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i gave you my best attempt at something that explains why it is true, but without being heavy

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bc i think you don't want the heavy shit

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(it'll involve series, which are like summations but infinitely long -- and you are only beginning with finite ones!)

devout bison
#

sorry the message wasnt loaded so i typed again

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f(x+y) = f(x) * f(y) is this always true?

willow bear
#

it is true for the function f(x) = cos(x) + i sin(x), and for all functions of the form f(x) = e^(kx).

devout bison
#

and here is something how can we draw these functions

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with numbers that dont exist in reality

willow bear
#

"don't exist in reality" is almost a derogatory way to refer to complex numbers.

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just because they aren't real does not mean they do not exist as mathematical objects.

devout bison
#

ik they exist in math

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and a very

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essential part

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inclluding a miracle

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the fractals like one u see in my prophile

willow bear
#

unfortunately, it is not easy to draw graphs of functions where the input or output (or both) is complex.

willow bear
#

for a function with real input and complex output, or complex input and real output, you can make a 3 dimensional sort of graph

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with 2 axes for the complex variable and 1 for the real

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it'll be a surface or a curve

#

but for complex->complex you would need 4 dimensions to do it like that

devout bison
#

so kinda like fractals but more complicated

willow bear
#

so usually for those functions, if they are plotted at all, they do something more sophisticated like colors

willow bear
devout bison
#

u know how we draw fractals right?

devout bison
#

what do u mean by 4dimensions

#

and why did we use 2 axes for complex

willow bear
#

complex numbers form a plane

#

you know this, right?

devout bison
#

no

willow bear
#

bruh

#

you have a Mandelbrot set on your avatar and you talk about fractals but you don't even know basics of complex numbers?

devout bison
#

i only know what they are

#

i am mid school

#

and i searched how fractals work but idk what u say the complex surface

willow bear
#

ok well heres the issue

#

if you ask about stuff like euler's formula like you did above

#

people are going to assume you are familiar with some basics of complex numbers

#

so you should go learn that

devout bison
#

ik the euler number

#

and what it is

#

((x+1)/x)^x=y when x goes to infinity y goes to e

devout bison
#

but not the "complex surface"

#

can u send a video orexplain it

static mesa
#

can i ask combinatorics here

devout bison
#

what is ur question

static mesa
# devout bison what is ur question

jamies dad allows him to choose 8 cars for his birthday

jamie's dad has 6 aventadors , 5 r8s , 4 bmws

in how many ways can jamie pick such that there're an equal ammount of r8s and aventadors

#

@devout bison

devout bison
#

the amount of all possibilities

#

15P8

static mesa
#

i want the combinations only pls

devout bison
#

so i think the pssibility for each will be

#

6P1*5P1

#

6P2*5P2

#

6P3*5P3

#

6P4*5P4

#

6!*5!

#

<@&286206848099549185>

#

sum these

#

divide by

#

15P8

#

wanna get explanation

#

?

#

sum these- this will give u the n of possibilities where number of r8 and avendator equal

#

when u divide itwill give u the possibility

static mesa
devout bison
#

u see

#

u have 6 cars from that type

#

your ability of taking random u have 6 chances

#

u took one

#

u r left with 5 chances

#

one more take one minus chance

#

now for each single choice u can make on first run which is equal to 6

#

in the next run u have 5 different choices

#

but these willl change

#

it is like a timeline game

#

where u control the timeline

#

as u made a choice

#

u entered an alternate timeline where

#

u can make 5 different choices

#

with each next choice

#

u type that timeline more

#

but still

#

u have other timelines either

#

@everyone how can i put images there

#

now if u start with 5 cars

#

there are 5 possibilities

#

u made one

#

now u have 4 possibilities

#

but imagine

#

u could have made another choices

#

and ur next generation possibilities would have changed

#

if the order doesnt matter

#

instead of permutation we use combination

#

4P3 means

#

u start from 4

#

and each single time multiply it to -1 number

#

until the amount of numbers is 3

#

so 4P3=4 * 3 * 2

#

see 3 numbers

#

started from 4

#

and multiplyed them to each other

#

@static mesa

#

?

#

could u do it

#

also i made a mistake if u saw

#

i had to use the combination

#

so it will be

#

@static mesa

#

?

static mesa
#

i think i get it

#

thx man

devout bison
#

so instead of p u will right C ig

#

there is only 1 difference between c and p

#

u divide p into the number of timeline generations(the number on the right)

#

this is a chat gpt explaining

#

i tought it will be more accurate so i sent this one

#

the previous was mine

tender questBOT
#

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

devout bison
#

u divide p into the number of timeline generations(the number on the right) and get c

#

so called the combination

#

u use permutation when choice order(timeline order) matters

rare fiber
# devout bison so instead of p u will right C ig

There’s a couple more corrections to make. you can’t make all these cases, and you’ve got to complete your process. I don’t think You can ignore the ways of choosing the BMWs

devout bison
#

i sent the other bot explanation for accuracy

rare fiber
#

For example the 1A , 1R case is not possible as you need 6 BMWs(we only have 4) to choose 8 choose

devout bison
#

i don't remember anything like that in my explain

willow bear
#

ever.

#

zero exceptions. if you can verify it without chatGPT then it means you never needed chatGPT in the first place.

devout bison
#

well i sent it only cuz i tought my explain was mindmixing

mossy quiver
#

chatgpt doesnt know what the hell it is talking about

devout bison
#

also the one in file is ai generated

rare fiber
# devout bison 6P1*5P1

You did this case, then you asked them to replace permutation by combination, by which I inferred that you meant do 5C1 * 6C1? Did I misinterpret you?

mossy quiver
#

it is a language model. it is designed to create coherent sentences, it is not your google

devout bison
#

the writings upwards are mine

willow bear
devout bison
#

since 1!=1

#

what's the problem there

#

also i counted several mistakes in my own

#

so i simply gave the idea of the way of possibilities

#

anyways

#

@static mesa u can ask again

#

there are more people

#

more miinds

#

oh damn' man

#

am gonna delete chat gpt

#

what the hell is this

willow bear
#

word of advice: if you are not 120% confident that you know how to solve a problem, then it's better not to try to help at all.

devout bison
#

ik how to but i may have done calculus or mind mistake

#

as i said earlier

willow bear
#

this metaphor will be unpleasant but it needs to be said:

what you have taken is basically the textual equivalent of a huge pile of shit, and we now have to live with it and smell it all.

devout bison
#

my mission was to give the idea of doing it

willow bear
#

and somehow shovel it all away.

devout bison
#

instead of talking maybe u help them

#

also u can't say the idea was wrong

#

so ig he kinda understood the method and

#

here we wait for u

willow bear
#

there may be a grain of truth there but it's buried under a pile of shit

devout bison
#

what is ur explain

willow bear
#

this is the original problem:

jamies dad allows him to choose 8 cars for his birthday 

jamie's dad has 6 aventadors , 5 r8s , 4 bmws 

in how many ways can jamie pick such that there're an equal ammount of r8s and aventadors
devout bison
#

yeah

willow bear
#

we are choosing 8 cars from this set with the condition that the number of R8's and aventadors

#

if we choose a aventadors, b r8's and c BMW's, the number of choices will be C(6, a) * C(5, b) * C(4, c). it remains to be seen what values of a, b and c are possible.

#

we know that a=b and that a+b+c=8, leaving us with the following possibilities:

  • (0,0,8) -- rejected: not enough BMWs
  • (1,1,6) -- rejected: not enough BMWs
  • (2,2,4) -- possible
  • (3,3,2) -- possible
  • (4,4,0) -- possible
devout bison
#

so u done?

daring tapir
#

(Not that relevant to the problem but doing it as if all the cars are unique would be a fun exercise)

devout bison
willow bear
daring tapir
willow bear
#

if OP cares about solving the problem and understanding it, they will complete the last step

#

if not, they will not

devout bison
#

c'mon seemingly u couldn't huh

willow bear
#

???

devout bison
daring tapir
daring tapir
devout bison
daring tapir
#

We are considering all bmws as one, all r8s as one and all aventadors as one

devout bison
#

she has that behavior that plagues me also she didnt help just blab

daring tapir
devout bison
#

@willow bear we are waiting for u

#

especially @static mesa

willow bear
#

waiting for what?

#

for me to give the answer?

daring tapir
devout bison
willow bear
#

i gave you everything needed to get the answer yourself

#

the fact you're choosing to pester me for the last step is entitlement on your part

daring tapir
#

Exactlt

daring tapir
willow bear
#

you know the saying "you can take a horse to water but you cannot make it drink"

onyx panther
#

You guys are getting out of control.

daring tapir
devout bison
devout bison
#

this is not mine but

#

@static mesa is probably on exam

#

he said he only needed combinations

daring tapir
devout bison
#

thats why we are waiting @willow bear

#

@willow bear

#

@willow bear

#

@willow bear

daring tapir
#

Someones begging to be banned

willow bear
#

<@&268886789983436800> we got some kinda harassment going on here

#

pingspam?

devout bison
#

what is a ping spam

willow bear
#

what you just did

coarse marsh
#

@devout bison please stop repeatedly spamming and pinging Ann

devout bison
#

also u typed on ur own upwards that u could be pinged

devout bison
#

she said that she could be pinged

#

anyways

#

<@&286206848099549185>

coarse marsh
#

No one needs to be pinged 4 times in a row

devout bison
#

since this is a math server

#

not blabbing course

daring tapir
#

They got it already bruh

devout bison
#

still that is a math site not blabbing

daring tapir
#

Soo?

coarse marsh
#

Ann has laid out a substantial amount of help for the OP. We don't just straight up give out answers here so idk what you're waiting for, you are currently the one blabbing

devout bison
#

by just typing down what has given? and even so, what's the case with ann anyways

coarse marsh
#

Stop

devout bison
#

i pinged her for the answer u said don't and that's all but what's the case of urs anyways

willow bear
devout bison
hallow lodge
fair basin
#

Can I ask a high school calc question here?

hushed sphinx
narrow oxide
#

I don't need help here but I enjoyed this problem

silent oasis
#

Why did he use less than equal instead of less than sign?

willow bear
#

strict inequality is not a concern here

#

sure you could say these inequalities are strict. but (a) nobody gives a shit and (b) there is no obligation to write a statement that is as strong as humanly possible

silent oasis
#

So, how did he reach third line from the second one?

willow bear
#

take reciprocal of everything

silent oasis
#

does it change the sign?

willow bear
#

it flips the sign

silent oasis
#

from less than to greater than

#

do you have any example

willow bear
#

example of what?

silent oasis
#

how the flipping happens

willow bear
#

are you asking why 0 < a <= b implies 1/a >= 1/b...?

silent oasis
#

yeah

willow bear
#

like the formal proof?

silent oasis
#

yes.

willow bear
#

a <= b implies b - a >= 0

#

1/a - 1/b = (b-a)/(ab) = (b-a) * 1/a * 1/b >= 0

#

b-a >= 0, while 1/a and 1/b are each positive
thus 1/a - 1/b >= 0

#

is this what you wanted

silent oasis
#

yes

silent oasis
#

are 1/a and 1/b positive because both a and b are greater than zero?

willow bear
#

yes

hushed sphinx
#

The conclusion isn't even true if a and b have different signs.

viscid thistle
#

hey, sorry to interrupt but if i have the quadratic approximation (second order taylor expansion) of cos(x)

#

how do i find the quadratic approximation of cos^(1000) x?

#

approximately

hushed sphinx
#

If a and b are both negative, the conclusion is true again, but we'd need some modifications to the reasoning Ann showed.

hushed sphinx
viscid thistle
#

cos(x) = 1- x^2 + x^4/4! + ... right?

#

(1 - x^2 + x^4/4! + ...)^1000 = ?

#

it's a bit hard

hushed sphinx
#

Or perhaps just wing it:
If you imagine multiplying out (1 - x^2/2 + o(x^2))^1000, there will be some times that contain one or more factors of o(x^2). You're not interested in them; they'll have too high degree to matter for your quadratic approximation. Then there will be terms containing factors of 1 and factors of -x^2/2. There you're interested in exactly those that have one factor of -x^2/2 and 999 factors of 1. How many of those are there?

viscid thistle
#

like can we try with sin(x) for example?

#

what am i looking to do exactly

hushed sphinx
#

I don't think I have any better explanation ready than what I just said.

viscid thistle
#

I agree with the extra O(x^2) term part

#

every terms of higher degree gives you an even higher degree so we don't care

#

But the last sentence i'm not sure how to put to practice

hushed sphinx
#

So you agree that the quadratic approximation you're looking for will also be the quadratic approximation of (1-½x²)^1000?

viscid thistle
#

which we don't care for but yeah, do we still not leave it there regardless?

hushed sphinx
#

Oh, I thought those were the ones you jsut agreed could be ignored.

viscid thistle
#

Yes well technically i can ignore, i just thought formally you'd write O(x^2) as well right?

viscid thistle
#

wait so just x^2

#

wait i'm being stupid probably lol

#

okay nvm

hushed sphinx
#

Okay, so let's write that out with the binomial theorem:
$$ (1 + \tfrac12 x^2)^{1000} = \sum_{k=0}^{1000} \binom{n}{k} 1^{n-k} \left( \frac{x^{2k}}{2^k}\right) $$

obsidian monolithBOT
#

Troposphere

hushed sphinx
#

The k=0 term is just 1.

#

Every term with k>=2 has too high degree to care about.

viscid thistle
#

true

#

okay i think this part is fine

#

what about more termst hough

#

let me think of a question

hushed sphinx
#

So there's now only one term left, namely the k=1 term.

viscid thistle
#

okay so what about for sin(x)

#

this time it's a cubic approximation for anything meaningful

#

because it has no quadratic term

hushed sphinx
viscid thistle
hushed sphinx
#

Ah, right. Sorry.

viscid thistle
#

anyway no problem i get the idea i think my main problem is "more terms" in the expansion

#

by more terms i mean

#

multinomial expansion i guess not binomial anymore

viscid thistle
hushed sphinx
#

Do you know multinomia expansion (which would make it easier) or were you just guessing the word?

viscid thistle
#

cos(x) = 1 - x^2/2 + O(x^3)

i'm curious what would be the right way to write out: (cos(x))^1000 = 1 - 500(x^2) + O(x^3)

viscid thistle
#

but not too familiar

viscid thistle
#

but like if i were to reason this out

#

it'd be: (1 - x^2/2 + O(x^3))^ (1000) right?

#

how do you deal with that?

hushed sphinx
#

I'm confused. Wasn't that was we just did?

#

Or you're asking for a formal justification for ignoring the O(x³) terms?

viscid thistle
#

which is sound yes

#

but like what if you just want to incorporate that into our expansion

#

instead of outright deleting it

#

so instead of writing $\qty ( 1 - \frac{x^2}{2})^{1000}$, how would we do it with the presence of $\qty ( 1 - \frac{x^2}{2} + o(x^3))^{1000}$

obsidian monolithBOT
#

!Kiz__

hushed sphinx
#

Hmm, let's define f(x) = 1 - x^2/2 for brevity.
Then we're looking at (f(x) + O(x^3)) ^ 1000, and we want to argue that this is f(x)^1000 + O(x^3).

#

Binomial theorem again: $$ (f(x) + O(x^3))^{1000} = \sum_{k=0}^{1000} \binom{1000}{k} f(x)^{1000-k} O(x^3)^k $$

viscid thistle
obsidian monolithBOT
#

Troposphere

hushed sphinx
#

Indeed.

viscid thistle
#

okay nice thanks, but wait my actual context is to use taylor on limits

#

therefore i know something like sin(x) approximates to x - x^3/6 + o(x^5) right?

hushed sphinx
#

O(x^5) not o(x^5)

viscid thistle
#

would small o notation not be the same as big O notation here?

hushed sphinx
#

Or alternatively ... + o(x^4).

viscid thistle
#

oh

hushed sphinx
#

No -- for example, x^5 is O(x^5) but is not o(x^5).

viscid thistle
#

can u briefly explain it then?

#

why o(x^5) isn't x^5?

hushed sphinx
#

We say that f(x) is o(g(x)) if f(x)/g(x) goes to 0 as x->0.
We say that f(x) is O(g(x)) if f(x)/g(x) is bounded near x=0.

#

In other words, o(x^5) stands for a function that goes to 0 strictly faster than x^5 does.

#

But O(x^5) means one what goes to 0 at least as fast as x^5 does.

viscid thistle
#

Oh i see, i get it

#

nice

#

okay so i think back to my question

#

sin(x) = x - x^3/6 + o(x^4)

#

how does this follow:

willow bear
#

i just explained this exact same q to another person

viscid thistle
hushed sphinx
#

I'm too lazy to go through and figure out exactly where they are, but I imagine there might be some signs that need adjusting.
And instead of "because 1/x and 1/y are both positive" we'd need to say "because 1/x and 1/y are both negative, their product is positive, ad therefore ..."
Not deep changes, just pesky.

willow bear
#

well they are deep if you have zero familiarity with proofs or zero familiarity with inequality manipulations

hushed sphinx
#

Fair.

daring tapir
daring tapir
#

Thats a fucking lie lmao

agile sparrow
#

I still crossmutiply with problems of < and >

#

Aand cancel terms each side

daring tapir
#

We were taught inequalitirs the first day we started jee prep

agile sparrow
#

I'm himm

daring tapir
#

Not considering like the triangle inequality or am-gm shit

agile sparrow
#

u can't do that

daring tapir
#

At least afaik

agile sparrow
#

(x-2)/(x-4) > (x-6)/(x-4)

#

then u have to take any one to the other side

#

U can't just cancel out the denominator

daring tapir
#

If its not you can still cancel

#

Just change the sign

#

Ig

daring tapir
agile sparrow
#

nuh uh

daring tapir
#

Lmao okay

agile sparrow
#

nuh uh

naive marsh
#

Anyone have a good strategy for review the AP test

narrow briar
#

hi! im on highschool and i love maths. i like functions but the content on the highschool lessons seems very easy and i want to learn more about calculus. I learnt limits and derivatives by the textbook by my own, but the book doesnt explain integrals. Can someone tell me how can i learn integrals and that kind of things? thank you

daring tapir
#

Thomas/stewart etc etc are all good books since you can learn from books on your own

hushed sphinx
#

Plan A would be to ask your teacher if they can recommend some material. Schools sometimes have old advanced textbooks sitting on a dusty shelf somewhere.

narrow briar
#

thank you

#

and do you know any web or youtube channel for it?

hushed sphinx
#

If you're working that far ahead, you might consider if you should be looking at some proof-based real analysis instead of just forging ahead to integrals.

daring tapir
narrow briar
hushed sphinx
#

Limits, derivatives, etc, but presented with theorems and rigorous proofs of everything instead of "here's the steps you must follow".
For all I know, that might actually be what you've already read -- it varies a lot between parts of the world whether one even distinguishes between "calculus" and "real analysis" in this way.

hushed sphinx
#

As a quick touchstone example, do you know what the intermediate value theorem says -- and would you have an idea of what would be necessary to start proving it?

hushed sphinx
#

Good, that means what you've been learning is not proof-based real analysis yet, and my suggestion to look into that won't waste your time. :-)

#

This is a topic where you'll pretty much need to use books rather than videos as your learning materials, though.

#

If you're on good terms with your teacher (and the teacher is somewhat competent), I'll repeat my suggestion to ask them. The teacher knows you better than we do, and can make a more educated guess at whether you should just be thrown straight at Baby Rudin or find a softer-and-friendlier introduction instead.

urban stream
#

using this bc I couldn't find a channel dedicated to geometric series

#

is this correct?

#

its the evaluation of this sum

hushed sphinx
#

!nogpt

tender questBOT
#

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

hushed sphinx
#

In this case I don't immediately see any error, though.

urban stream
#

yeah it was incorrect

#

i got the correct one now haha

#

i think this is the one

#

$S = \frac{15}{2} \left(1 - \left(\frac{3}{5}\right)^n\right)$

obsidian monolithBOT
hushed sphinx
grim elk
urban stream
#

shit I'm gonna have to do it again now

urban stream
willow bear
#

are you 110% sure that you wrote it correctly and made zero typos?

#

@urban stream

#

asking because the probably-intended meaning of the sum doesn't align with the sum as it is written right now: $$\sum_{r=1}^n \frac{15}{4} \cdot \paren{\frac{3}{5}}^n$$

obsidian monolithBOT
#

|Ann⟩

hushed sphinx
#

(What Ann is saying is that it looks extremely likely that the n'th power in that formula should have been an r'th power instead).

urban stream
willow bear
#

ok so then can you post the correct sum

urban stream
#

the sum of the terms are \sum_{r=1}^{n}\frac{15}{4}\left(\frac{3}{5}\right)^{r}-1

#

$\sum_{r=1}^{n}\frac{15}{4}\left(\frac{3}{5}\right)^{r}-1$

#

the -1 is gonna be with the r, couldn't type it on with latex

#

$\sum_{r=1}^{n}\frac{15}{4}\left(\frac{3}{5}\right)^{r-1}$

obsidian monolithBOT
urban stream
#

got it

#

@willow bear

willow bear
#

ok

#

so

#

!status

tender questBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
urban stream
#

2

#

the question later on says to find the least value of n for which sum of infinity - sum of nth terms <0.045

bold wren
#

Hey people someone told me to come to this channel maybe i will find what i want but promise you will not laugh after i say my request? I really need it but dont ask why, ok?

urban stream
#

no need to be ashamed

bold wren
#

Is there any function that has like one point like for example (1;3) and that's it no more points?

hushed sphinx
#

Many qustions cannot be answered well without knowing why, though.

upbeat wyvern
#

How do I calculate the area of this pool using calculus?

upbeat wyvern
#

Aight

urban stream
#

This was the whole q

#

,rccw

obsidian monolithBOT
urban stream
#

Struggling with C

winter comet
#

you really don't have any lengths or units tho

#

soo

#

imposibleh

#

XD

golden cairn
#

How do I solve this?

hushed sphinx
#

Didn't you already ask that yesterday?

#

And if you keep asking the same question, people will just keep giving you the same answer that you didn't find helpful the previous times.

#

Would you be able to solve this equation: 3Ā·xĀ·1.792 = (2x-3)Ā·0.693?

golden cairn
#

Yeah

#

I got -0.52

#

That’s the same answer for the question I asked

#

So you got me the correct answer but I don’t know what you did

hushed sphinx
#

The previous times you asked, you got to
3xĀ·log(6) = (2x-3)Ā·log(2)
and then got stuck.

golden cairn
#

Yeah

hushed sphinx
#

I simply calculated the values of the logarithms: log(6) = 1.792 and log(2) = 0.693.

#

(Though now I see I should probably have used the base-10 logarithm instead of the natural one, sorry).

golden cairn
#

Yeah but the teacher said we can’t use calculators

#

Is this the next step?

hushed sphinx
#

Hmm, without a calculator, I don't think there's any reasonable way to reach the value -0.52 as an answer.
(I'm assuming you don't have a slide rule or a log table either ...)

golden cairn
#

Nope

hushed sphinx
winter comet
#

they prob want you to distribute and solve for the exact value of x

golden cairn
#

But I skipped a step

#

And just showed what I thought might have been the next step

golden cairn
#

I know I thought so

winter comet
#

2xlog2 - 3log2 isn't that

golden cairn
#

I tried using these

winter comet
#

you should subtract 2xlog2 from both sides instead

golden cairn
#

Okay

winter comet
knotty pike
winter comet
#

2x and 3 are both outside the log function

winter comet
hushed sphinx
#

I imagine when you solved my version with decimal numbers, your next step was to combine all the terms with x in a single term.

winter comet
winter comet
#

and then divide by everything thats left

#

to solve for x

hushed sphinx
#

So the point here is that log(6) and log(2) are just two particular numbers. They behave the same in an equation as 42 and 18827 would have done.

golden cairn
#

Right now

knotty pike
hushed sphinx
#

So what you should be thinking first when you see

(3Ā·log6) x = (2Ā·log2)x - 3Ā·log2
is not "uh oh there's a logarithm there, I need find and use a log rule", but instead "ho hum, there's some constant number there, it doesn't affect how I solve the equation precisely what the constant is".

winter comet
winter comet
hushed sphinx
golden cairn
#

I got the answer

#

I did the factoring

winter comet
winter comet
golden cairn
#

I just factored out the x and then did (-3log2)/(3log6-2log2) and then I got -0.5213

hushed sphinx
#

Perfect.

winter comet
#

yeh

golden cairn
#

Thanks

knotty pike
# winter comet thats correct...

[3-2log6(2)]x = -3log6(2)

x = - (3log6(2)/3-2log6(2))

x = - (3log6(2)/log6(6³)-2log6(2))

x=-(3log6(2)/log6(6^3.2^-3))

doing that u got:

x=-(3log6(2)/log6(27.2))

x=-(3log6(2)/log6(54)

x=-3log54(2)

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x=-0,5213

golden cairn
#

How do I solve this?

#

I tried the same method

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But it won’t work this time

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I keep getting the incorrect answer

hushed sphinx
#

The same general approach should work. Can you walk us through your steps that give an incorrect answer?

golden cairn
#

Okay so I got up to this step: xlog(3/2)+xlog5=2log5

#

I factored out the x

hushed sphinx
#

Smaller steps, please?