#precalculus

1 messages · Page 51 of 1

willow skiff
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so it's similar here, if you understand this concept
that you can mess up the translation you want if you don't follow the order
then you're good to go, if you practice of course

unborn brook
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Sure but my point is at some point we have to define arbitrary stuff to avoid ambiguity

willow skiff
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in terms of mathematical notation and communication, absolutely

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the issue here is your problem is about understanding how transformations work, right?

unborn brook
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it's not that I'll memorize some distorted mnemonic to deal with the operations

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I just wondered why it is the way it is

willow skiff
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honestly I think this is doing you more harm than good

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the picture

unborn brook
unborn brook
willow skiff
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I wouldn't memorise this order

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cause it's not even true that you have to follow that order to get it right

unborn brook
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Yup I've realized that translations and transformations are inherently interchangeable

willow skiff
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cool

summer ruin
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there are operations for which order doesn't matter and those for which it does matter

terse aspen
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Hello can someone help me on describing the end behavior and any ezcluded values with limit notation in dms pls

winter comet
terse aspen
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Hi yes

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Sure

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So i have this

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Y= 4x/x^2-4

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Im doing the top problem

winter comet
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y = 4x/(x^2-4)?

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ok

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doesnt send full problem 😔

terse aspen
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Domain and range is easy but im confused on “describing the end behavior and any excluded values with limit notation”

terse aspen
winter comet
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two of them :>

terse aspen
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Yes

winter comet
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do you know limits?

terse aspen
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Domain is all reals and x cant equal plus/minus 2 and y is all reals

winter comet
#

yeah

terse aspen
winter comet
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do you know the limit approaching these domain restrictions/excluded values of x?

winter comet
#

well you'd look at the limit as x approaches -2 or 2 right?

terse aspen
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So theres 6 total lim?

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Yes

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Ok wait let me do and see if im right?

winter comet
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approaching 2, approaching -2, approaching infinity, approaching -infinity

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those are your limits, right?

terse aspen
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But what about middle

winter comet
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what about the middle?

terse aspen
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Yes

winter comet
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is there a discontinuity there XD

terse aspen
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Isnt it somthing like

winter comet
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is 0 an excluded value?

terse aspen
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-infinity

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No

winter comet
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then why are you looking at the behavoir approaching 0?

terse aspen
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Idk tbh

winter comet
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it tells you to look at end behavior (as x approaches +-infinity) and excluded values (as x approaches +-2)

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so you'd have four limits

terse aspen
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Oh ok

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So would there be any case where we are looking at 6 limits

terse aspen
winter comet
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with the same instructions, the function would have to have four discontinuities like this instead of two ^

winter comet
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thats seperate from the excluded values

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the end behavior is 2 limits

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always

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but in this case there are two excluded values and one limit for each value

terse aspen
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Oh ok

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I see ok

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So only 4

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Can you help me qith another problme

winter comet
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what is the other problem?

terse aspen
winter comet
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what is the denominator?

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x^t 8x^6 - 12x^3?

terse aspen
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X +8x^6 -12x^3

winter comet
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oh LOL

terse aspen
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My bad lmao

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No t

winter comet
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whats the highest power term in the limit?

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or just the highest power in general lol

terse aspen
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6

winter comet
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yeah

terse aspen
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In the denominator

winter comet
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try dividing the numerator and denominator by x^6

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x^6 sorry

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💀

terse aspen
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Wait what

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:/

winter comet
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divide the numerator and denominator by x^6

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so like

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[(13x^3 - 1502x^2)/x^6]/[(x+8x^6 - 12x^3)/x^6]

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you see what i mean?

terse aspen
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Like long division?

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Yes

winter comet
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no

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like (63x^3 - 1502x^2)/x^6 = 63/x^3 - 1502/x^4

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right?

terse aspen
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Wait

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The top is 63

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My bad

winter comet
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oh

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63 then

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same process XD

winter comet
terse aspen
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All good

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Why are we doing that

winter comet
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same answer in fact 💀

terse aspen
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I have that now

winter comet
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so then the denominator becomes

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(1/x^5 + 8 - 12/x^3) right?

terse aspen
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Wait one sec

winter comet
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so the limit should become this

terse aspen
#

Ok i havd that

winter comet
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ok

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now as x approaches infinity, what happens to 63/x^3?

terse aspen
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Smaller

winter comet
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right its approaching 0

terse aspen
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Yes

winter comet
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same with any term with x underneath

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so lim x->infinity 0/8 = 0, right?

terse aspen
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Yes only constant in the bototm

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Yes

winter comet
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yea

terse aspen
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So equal 0

winter comet
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so the limit is just 0

terse aspen
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🤯

winter comet
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fun fact: you can just take the term with the highest power in the numerator, and the term with the highest power in the denominator, and take the limit of the highest power in numerator divided by the highest power indenominator

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so like, here it would be lim x->infinity 63x^3/8x^6 = lim x->infinity 63/8x^3 = 0 still

gritty totem
winter comet
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because all the other terms are going to 0

gritty totem
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oh no, i was just saying because i saw the question and thought of a faster way of doing it

winter comet
#

or something liek it lol

gritty totem
winter comet
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it only works with infinite limits tho

terse aspen
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I am catching up on 5 pre calc lessons and 2 bc lessons

winter comet
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(or approaching -infinity)

terse aspen
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Can i have help with 1 mire

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Laast one

gritty totem
terse aspen
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Yea sure

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So i have y=3x/ absolute value phrase x-1

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And i have to find the domain and range of the function describe the end behavior and any excluded x values with limit notation

gritty totem
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the absolute value of x-1 is equal to two functions:

-(x-1) if x < 1 and (x-1) if x> 1

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the domain is, of course, how far to the left and how far to the right it can go

terse aspen
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Yes

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I see how -(x-1) works but how does the negative get there

gritty totem
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it has a vertical asymptote at x= 1 as well

terse aspen
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And horizontal of 3 ??

gritty totem
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that’s why the -(x-1) is important in this case

terse aspen
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But than what about this graph

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Thats the graphbof the equation

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How does the horizontal work here

gritty totem
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horizontal asymptotes are positive and negative 3

terse aspen
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Oh wait i see that

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Yes

terse aspen
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Is it allowed to go through?

gritty totem
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-(x-1) = 0
becomes x - 1 = 0
x = 1

x-1 = 0
x=1

terse aspen
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Ok

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I see

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So whats next

gritty totem
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you’re also looking for the domain and range

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the domain is how far left to right the function can go

the range is how low to high the function can go

terse aspen
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So x all real and y > -3

gritty totem
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let me see:

domain: (-infinity to 1) U (1 to infinity)
i’m not sure about range though

terse aspen
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Hole ok

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So the next part is describe the end behavior and any excluded X values with limit notation

gritty totem
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oh i see

gritty totem
terse aspen
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And thats it

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Oh ok wow thats weird

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What about the other 2

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As it aproaches infinity y is infinity and is it aproaches negative infinity y is negative infinity?

gritty totem
terse aspen
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Oh my god this is making sense

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I know i got it wrong originally but still

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Tha k you

gritty totem
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i’ll give you proof if you want to look into detail

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or i can explain it to you

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whichever option

terse aspen
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Wdym

gritty totem
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as to why the limits approach infinity make sense

terse aspen
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Yes pls

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Explain

gritty totem
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so, this is where the rules of a rational function come into play regarding limits approaching infinity

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one of the rules is that if the power of the numerator is equal to the power of the denominator, then the horizontal asymptotes is equal to the coefficient of the numerator divided by the coefficient of the denominator

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here, with the function that we were solving, the powers of both the numerator and denominator were equal

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that’s how we got 3 and -3

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so, with limits of infinity, the rule i mentioned still applies since the powers of both the numerator and denominator are the same

terse aspen
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Oh ok yea and what gets the denominator to 0 is vertical asympte? But how does slant higher top than bottom or higher bottom than top power wise

gritty totem
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also, yes, the vertical asymptote is obtained when you set the denominator of the function equal to zero

terse aspen
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How would i get the f(x) nunber of the limit if it is set to inifinity but the either the numerator power is higher than the denominator or vice versa

winged peak
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Hey guys, so Im learning functioms amd polynomials in my precalc class and I am so lost on the graphimg padt

So, I thought since the degree was positive, the graph falls to the left and since the leading coefficient was positive, it rises to the right

I failed a question bc I got the "a" part wrong

Could anyone help me explain how to understand the "finding the end behavior" better?

gritty totem
#

greater than: the horizontal asymptote does not exist

less than: the horizontal asymptote is 0

terse aspen
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Oh ok

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I see thank yiu fro all the help

gritty totem
winged peak
#

Is anyone gon help me... halp

gritty totem
gritty totem
winged peak
#

Ok this ia gon take me an hour to despipher ill brb 😭

winged peak
gritty totem
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@winged peak i do want to add with the function behavior:

for example, when they tell you as x approaches infinity -> f(x) approaches infinity, it’s telling you to read from left and right or right to left

winged peak
#

Just in advance, I have a slight lesrning disability so im kinda slow 😭

gritty totem
winged peak
#

Thank you, Im new to my university and i have no intention of fucking around over here 😭

terse aspen
winged peak
#

Alr I uave to do a DIFFERENT question thats not the one i showed on paper, but ill ask you for help later. Its ok if u dont anseer immediately or jave othee things

terse aspen
#

Draw your arrows than your bounces sqiuggles and straights if your graphing

winged peak
#

Yes im graphing on a computer i just showed my work on paper

terse aspen
#

Am i right @gritty totem ?

gritty totem
#

and you can factor the function to see where the zeros are located and use the information to sketch the graph after

terse aspen
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Yep but if its factored out dont take the highest degree there you need to add them up including if there is a x without a clearly defined power its 1 if not another

terse aspen
gritty totem
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and what’s the test about?

terse aspen
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The bc 1.1 is easy its just areas of rectangles for the underside of a quadratic thingy

cerulean spire
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hi, im new can anyone pls explain what calculus is. I really would like to learn

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and teach me the basics and stuff

gritty totem
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differential calculus is finding the rate of change of a function such as derivatives (which is the slope of a function)

winter comet
gritty totem
winter comet
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yeah

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💀

gritty totem
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oh i see

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i don’t mind someone being curious to calculus at all, but if they’re wondering what algebra is, then algebraic work has to be covered first

winter comet
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could just say "study of changing things and....infinite things :>"

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😂

gritty totem
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oh i see

winged peak
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Nvm it was right I was being delusional

gritty totem
winged peak
#

Bro, the website I do my hw on is called aleks

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and if I get 1 problem wrong, I'm assigned more questions

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And it's like I'm traumitized at this point and in tears

gritty totem
#

That name hasn’t popped up in my mind in years

winged peak
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Fr?

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R u in a university?

gritty totem
#

Yep

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College freshman

winged peak
#

This website is fucking ass like it charges me money to do my damn hw and Ion even use the damn e book

winged peak
gritty totem
#

I have multivariable calculus and intro to proofs - which is why I have experience with precalculus

winter comet
gritty totem
# winged peak SLAYYY MEE TOOO

and my homework is mainly on paper; some is through technology but it’s for a “quick check” from the concept i read for intro to proofs

winter comet
#

it still technically counts though... ecstasy

winged peak
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Wait

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this channel banns the topic regarding ... " i - q"

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Bc I was literally tryna compliment u omg 😭

winter comet
#

i mean like idk if it can be called 'experience' but

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:l

gritty totem
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oh i see

winter comet
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💀

gritty totem
#

but hey, there’s nothing wrong with self-teaching yourself a subject

gritty totem
winged peak
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Yeah

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I just responded to u "Wow, ur i - q must be up there w albert" and the server banned it due to irrational arguments over it idk

winter comet
winged peak
#

Honestly Ig for a server w 200k users, sounds reasonable

gritty totem
winged peak
#

Idk how long u been here but has this disc chat had any chaotic moments

gritty totem
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just joined today so i don’t have much of a clue

winter comet
winged peak
winged peak
winged peak
# gritty totem Yep, this one’s right

Alr tysm for clarifying bestie. Transitioning to college has been like, kinda wild if I'm being honest. I love it, but it's quite difficult to adjust here and there. The math hw I was just doing was only like, prep, which was tedious asf.

And the weird part is, the math prep usually has nothing to do w the exams, or lecture. Like I barely passed my first exam which is giving me hella anxiety. 😭

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It's nice to meet u tho! Hope to talk to u more < 3

gritty totem
gritty totem
winged peak
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Do u dorm ???

gritty totem
winged peak
#

ANYWAYS I GTG TO WALMART AND BUY TOILET PAPER BYEEEE

winged peak
winter comet
gritty totem
winged peak
safe basin
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Bros name opencry

daring tapir
stiff sluice
daring tapir
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sub 1/x = t

safe basin
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af(bx-c)+d vertically stretches f by a, horizontally stretches f by b, horizontally translates f by c, and vertically translates f by d

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Obv each of those can be done individually too or in whatever combinations but I just stuck it all in one place for conciseness

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So for these to be correct you’d have to stick the vertical translation outside of the argument of f

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Cause f(x) + k vertically translates f by k

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For the factoring thing it depends, you just want to be able to express it in a form where you can extract this info relative to some function f

earnest flower
#

Can someone check if these are correct

g(x)=2x^2 -6x+4
h(x)=-2x^2 +10x -12
j(x)=3x^2 -12x +9

willow skiff
#

,w polynomial through (-3, 40), (1, 0), (2, 0)

obsidian monolithBOT
willow skiff
#

,w polynomial through (-3, 0), (1, 8), (2, 0)

obsidian monolithBOT
willow skiff
#

,w polynomial through (-3, 0), (1, 0), (2, 15)

obsidian monolithBOT
willow skiff
#

only g(x) is correct

topaz wave
#

do you have reviewer on pre cal guys?

willow skiff
earnest flower
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Nvm

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I didnt know if the - - 3 would make it positive when factoring now i jnow

exotic barn
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I sent a video in your help channel and you deleted your msg, you're weird for that

rotund jasper
#

sorry if it's wrong channel but can u guys help me this

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Given sequence a1= 1, a1<a2<...<ak such that these positive integers < m and coprime with m. Prove that if the sequence a1,a2,...am is an arithmetic progression with at least 3 numbers, so m will be a prime or an exponential of 2

cloud escarp
#

hello guys
Im new here can anyone suggest me or guide me where i should start from.
Im in High School

exotic barn
#

on YouTube

cloud escarp
#

anything else would u like to suggst for me

exotic barn
#

maybe start

daring tapir
#

😭

keen swift
#

I am nerd

warm cove
#

Precalculus test was easier than I expected, I am definitely improving.

slim lark
#

Hello everyone I wanted to start calculus but I lack many concepts I have studied math till 10th grade Real Numbers
Polynomials
Pair of Linear Equations in Two Variables
Quadratic Equations
Arithmetic Progressions
Triangles
Coordinate Geometry
Introduction to Trigonometry
Some Applications of Trigonometry Circles
Constructions
Areas Related to Circles
Surface Areas and Volumes Statistics
Probability. So I wanted to know what else do I need to cover

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can anyone help

slim lark
#

someone recommend me to cover functions, integration, differntiality,limits and continuity

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is it enough?

slim lark
slim lark
#

I know but

slim lark
#

highschool

restive glacier
slim lark
#

ya what about you?

restive glacier
restive glacier
slim lark
#

17

restive glacier
#

Ok. good.

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I am 26

slim lark
sleek folio
#

How do I proceed to prove this?

river drift
#

,rccw

obsidian monolithBOT
low yoke
#

Hey there! can someone explain me the difference between the slope and the rate of change? I understand them as the same, am I correct?

low yoke
#

And why they got different name?

winter comet
#

💀

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that was supposed to be a joke

winter comet
low yoke
#

I meaned, why In my book it has like 2 different terms for the same stuff

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im not native english :/

sleek folio
#

Slope is defined for straight line

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Rate of change is for any function

river drift
#

"slope" is an interpretation of the derivative driven by the graph of a function, whereas "rate of change" is driven by interpreting a function as modeling a physical quantity

low yoke
#

Okay, understood

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thank you guys

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❤️

serene crag
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i just got a 43 on my precalc test

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am i cooking

upbeat yarrow
#

no

winter comet
#

☠️ ☠️

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😂

serene crag
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idk what i got wrong either

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i just have a non-curving ap teacher

winter comet
winter comet
serene crag
#

😭

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she doesnt even follow ap cirriculum

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she makes her own

winter comet
terse aspen
#

Can someone help me on piece wise functions they are easy I just dont grt this problem 😐

terse aspen
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Number 3

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One of them is dne I think its the first but idk why

winter comet
#

have you tried graphing it? it might help with understanding whats going on

terse aspen
#

I have not but on my test there wont be enough time he said

winter comet
#

but for (a) you're gonna wanna look at the graph approaching 2 from the right and from the left

winter comet
#

because its -x^2 + 5 for x<2 (on the left side of x=2) and 4x for 2<=x<4 (on the right side of x=2 including x=2)

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so you're going to want to know lim -> 2- (-x^2 + 5) and lim x->2+ (4x)

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if they evaluate to the same thing, then the limit is what they both evaluate to

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if they evaluate to different things, the limit does not exist

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am i making sense or nah 💀

terse aspen
#

winter comet
#

💀

winter comet
terse aspen
#

Bro idek how we got to evaluting them

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Ok

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One sec

winter comet
#

yeah

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well first of all, as x approaches 2 do you see graphically that the limit doesn't exist?

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like both sides approach different things

terse aspen
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Yes

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Ita like this one

winter comet
#

lim x-> 2- f(x) is not equal to lim x-> 2+ f(x) right

terse aspen
winter comet
#

but we can find numerically where each side approaches

terse aspen
#

Isnt it becuase 1 value having more than 1 y value

winter comet
#

without graphing it

winter comet
terse aspen
#

Yes

winter comet
#

so lets say you're approaching f(x) from the left

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lim x-> 2- f(x)

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since you're looking at x values less than 2, which part of the piecewise function can you use?

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remember the function is -x^2 + 5 if x<2, and 4x if 2<= x < 4

terse aspen
#

X<2

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First one

winter comet
#

yeah so you're gonna use the function for x<2 right

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so as x approaches 2 from the left, lim x->2- (-x^2 + 5) = the value you're approaching from the left

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make sense?

terse aspen
#

Wait are you literally subtracting like this or a dash

winter comet
#

lim x-> 2-
the - after 2 means its approaching 2 from the left

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lim x-> 2+ would mean approaching 2 from the right

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i shoulda explained that before 💀

terse aspen
#

When i look at it

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Just dont know how to see this qithout a graoh just mind

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🧠

winter comet
#

like you can just think of some arbitrary graph but you only care about the graph for x<2

terse aspen
#

Ok

winter comet
#

then approaching from the right, it should be the same value if the limit exists, right?

terse aspen
#

Yes

winter comet
#

so lim x->2+ f(x) is the limit of f(x) as x approaches 2 from the right

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which part of f(x) do you use?

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you're only going to realistically use the values to the right of 2 that are close to 2

winter comet
#

remember f(x) = {(-x^2 + 5) if x<2, 4x if 2<=x<4, and x^2 if 4<= x
if you're approaching 2 from the right but you only care about values close to 2, which of these do you use?

terse aspen
#

Only option is 2<_ x <4

winter comet
#

right

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so you're going to use the 4x part of the function

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so lim x->2+ f(x) = lim x-> 2+ (4x) = the value of the limit as f(x) approaches 2 from the right

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right?

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🤣

terse aspen
#

No

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The y values do not equal each other

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Wait what

winter comet
terse aspen
#

Ok i see

winter comet
#

basically you have to determine from which way you're approaching, and use the appropriate part of the piecewise function. if the limits from both sides both evaluate to the same number, then the entire limit is that number. But if the limits from both sides evaluate to different numbers, the limit doesn't exist

terse aspen
#

Oh i understand now

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Thank you so much

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🤯🤯

winter comet
#

😂

terse aspen
# winter comet 😂

How do i know thag my line parobola thingys are going thr same direction if its like this

winter comet
#

or just make a table of values as x approaches your discontinuities 💀

terse aspen
winter comet
#

but i don't know of an easy way to know, maybe there is an I just don't know it tho

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🤷‍♂️

terse aspen
#

Oh ok thanks tho

winter comet
#

i'd just plug in values to see xD

terse aspen
#

Thank you tho

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Lmao ok

viscid thistle
#

hi im in Gr 12 in pre calc with a mark of 64, its because of my first test. and right now im doing polynomial functions in pre calc. i know how it works but the word problems, applying polynomial problems in real life is a big challenge for me so i beg that someone give me a lengthy advice and some support please and thanks

winter comet
wanton parcel
#

Any single guys my age group plz dm me I want a bf to show my friends in school 😭

Rules :
17 or under

uncut mulch
#

@wanton parcel Please don't use this server for that kind of stuff.

warm cove
#

I feel threatened

warm cove
#

I studied for the wrong thing on the no calculator part on the test bleakkekw

small hedge
#

Bro fuck precalc

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i do not understand it

wraith jackal
#

Hello :) can someone explain to me how this works
(I also do not know what this is called)

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$x^{ab}-1=(x^a-1)(x^{a(b-1)}+x^{a(b-2)}+...+x^a+1)$

obsidian monolithBOT
#

Minute

wraith jackal
#

I know its related to (x-1) always being a factor of (x^n-1) for any natural number n but i dont get how you derive that from this

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also lmk if there was a better channel to pose this question in

safe blaze
#

By induction on b

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Or well by using x^n - 1 = (x-1)(1 + x + ... + x^(n-1))

wraith jackal
#

do you know what that theorems called

safe blaze
#

Hmm idk

#

It's kind of related to the geometric series formula

#

And cyclotomic polynomials

wraith jackal
#

ah thank you this is good reading :)

wraith jackal
#

@safe blaze apparently its the difference of powers identity with b=0 1 :P

#

i think this or something related was mentioned in the advanced algebra channel

#

yesterday 5pm aest

tame pine
#

Yo

viscid thistle
#

Yo

warm cove
#

Yo

winter comet
#

Yo

safe basin
#

Yo

agile ginkgo
#

$plot (sinx)$

obsidian monolithBOT
#

Progno

tame pine
#

,w plot sinx

obsidian monolithBOT
quasi elbow
#

how do we solve question 12?

night herald
#

is that the answer?

hasty lily
quasi elbow
night herald
#

yeah yeah

#

wait

night herald
#

do you the sign of each trig function in each quadrant?

#

@quasi elbow

quasi elbow
#

i do

night herald
#

also do you know what happens when you add $n\pi$ or $\frac{(2n+1)\pi}{2}$ to the argument of trig functions

obsidian monolithBOT
#

Black_Gold

night herald
#

??

quasi elbow
#

oh

#

i got it

#

thank you!

night herald
#

where were you stuck??

quasi elbow
#

i was writing cot(90-a) as cosec(a)

#

i rechecked

fringe atlas
#
#

Can anyone explain this last part

#

What if the product of ac is negative?

quasi elbow
#

can someone please explain this question to me? in this, we have to find the minimum and the maximum value of the given expression

exotic barn
#

since it's open upwards, it will tell you the minimum value is 3/4

#

in order to find the maximum we need to consider now the vertex form expression

#

sin²(theta) is bounded between 0 and 1

obsidian monolithBOT
#

bacc the sigma😔🤞

quasi elbow
#

how are we supposed to think of the process though, when we come across such questions?

#

if that makes sense

hasty lily
#

<@&268886789983436800> any moderators who wants a [ this person has been posting on here frequently asking for a dating partner ]

exotic barn
#

so might as well complete the square to get the vertex form etc

#

if it were instead of sin(x)^4 it was sin(x)^3 then it would be a bit more difficult

quasi elbow
#

got it, thank you.

jagged drift
#

@exotic barn Können Sie mir bitte mit Wahrscheinlichkeiten helfen?

quasi elbow
#

what is happening here

viscid thistle
quasi elbow
#

um

#

the whole thing

viscid thistle
#

okay

#

so

#

first

#

this part

#

for some reason i feel like this is wrong

#

cause pi equals 3.14

#

but

#

here they are taking pi as in radians

#

which equals 180degress

#

degrees

#

ah

#

thats the reason they said this

#

eh

quasi elbow
#

i am still very confused

willow skiff
willow skiff
#

sin of 1 degree is tiny

#

using the approximation $\sin x \approx x$ in radians

obsidian monolithBOT
#

higher's secret twin brother

willow skiff
#

,calc pi/180

obsidian monolithBOT
#

Result:

0.017453292519943
willow skiff
#

,calc sin(pi/180)

obsidian monolithBOT
#

Result:

0.017452406437284
willow skiff
#

there you go, they're very close

willow skiff
#

they drew a lot of lines yes

for instance, because 3 < pi, 1 < pi/3 and so sin(1) < sin(pi/3)

#

also sin has symmetry, so sin(pi - x) = sin(x)

so that is why sin(pi - 2pi/3) = sin(pi/3) = sin(2pi/3)

#

it is a lot of info yes

quasi elbow
#

i had an eight-hour study session so nothing is making sense to me anymore

#

i will get back to it later

#

but thank you

willow skiff
#

np!

brave shard
#

can anyone expalin to me how the denominator is turns into 5x-19??

summer ruin
#

multiply by x-6

brave shard
#

how does that make it 5x+19 though? shouldn't it be like x^2 -6x + 5x - 30 +4x - 24? thats what it is if you multiply x-6 with the denominator

brave shard
#

OHHH

#

your the goat my friend

#

thx

dense eagle
#

yw

wild phoenix
#

Well boys I'm cooked I'm way in over my head and there is a HIGH Likelihood I fail out of AP precalculus I will probably be here alot asking stupid questions this is a warning 🫡

unborn brook
#

Why is the slope of the secant line necessarily equal to the average rate of change between the two points? (I know the question is trivial and the answer might be obvious to most of you but I find this kind of counterintuitive. The slope is the same as long as the two points are the same, no matter what kind of shape the function is taking between the points. This boggles my mind. An explanation that goes "By definition..." makes it even worse.)

exotic barn
#

You wanna know how much is the average rate of change

#

Now if you drew a line through these two points (a,f(a)) and (b,f(b)) you would get a linear function

#

a line

#

And you would notice that the slope of that line is equal to the average rate of that function if you drew a triangle

#

and we call that green line a secant line because it intersects at two distinct points of f

winter comet
#

jkjkjk 😂

astral surge
#

i have created brainrot of math called mathrot let me elaborate a conversation using this mathrot "wsp dude have you been integrating and graphing to make that mtan line more proportional in a equation, yea i have been how could you tell did my omega alphnul give it away or was it limits"

astral surge
#

thank you fellow summation/sigma

winged notch
#

hi

#

anyone here that could help plz

winter comet
astral surge
#

chat i was hitting some precalc when i got a message i check and this is what my friend turned into am i cooked?

winter comet
astral surge
#

fr

astral surge
#

Y'all pre calc is fun and all but this about it

viscid thistle
rigid burrow
#

Hi guys I'm stuck at getting the derivative of this function, can I get an idea how to proceed?

willow skiff
#

expand and divide

#

$y = 2x^{2/3} + 2 \sqrt{2} x^{1/2 - 1/3} + x^{-1/3}$ then power rule

obsidian monolithBOT
#

higher's secret twin brother

rigid burrow
willow skiff
#

no problemo

tame pine
#

Yo

whole flame
#

Hello guys
I need references for which book I can use for Maths for class 12th boards?

quasi elbow
#

can someone please explain the concept of composite functions to me?

#

like, for instance, how is sin(x^2) a composite function?

uncut mulch
#

you have
trigfunction(something that isn't just x, )

quasi elbow
#

how does it make it "composite", though?

uncut mulch
#

function of (some other function of x)
its composite by definition

#

f(g(x))

quasi elbow
#

oh so like, x^2 is a function of x?

uncut mulch
#

yes

quasi elbow
#

got it! thank you 🌸

#

how are we getting this?

quasi elbow
#

according to this,

#

should not this be non-periodical?

#

because pi is irrational

willow skiff
quasi elbow
#

then why is f(x)= |sin(pi x)| + cot(3x/2) not a periodic function? if its period is coming out to be 3/2pi

willow skiff
#

the problem is that 1 is not any rational multiple of pi

#

or 2pi/3 is not a rational multiple of 1

quasi elbow
#

stupid question

#

what does one mean by rational multiple?

willow skiff
#

are all rational multiples of pi

willow skiff
obsidian monolithBOT
#

higher's secret twin brother

quasi elbow
#

then why is 1 not a rational multiple of pi?

#

i am sorry i am just really bad at it

willow skiff
#

then we could write $1 = \pi \frac{p}{q}$ or $\frac{q}{p} = \pi$ where $p, q \in \mathbb Z$

#

but pi is irrational

#

contradiction!

obsidian monolithBOT
#

higher's secret twin brother

quasi elbow
#

right

#

so

quasi elbow
willow skiff
#

the periods of sin 3x and |tan(x/2)| are rational multiples of pi

#

in fact you can see the combined period must be 2pi

#

that's the least common multiple of 2pi/3 and 2pi

willow skiff
quasi elbow
#

makes sense, thank you

viscid thistle
#

I started pre-calculus a couple of days ago and it's damn hard, and I can't understand very specific equations that I need help 😭

willow skiff
tender questBOT
willow skiff
#

you can ask in a help channel

glass cipher
#

yo

#

Anyone knows how to solve this??

#

pls

willow skiff
#

I answered your question here

quasi elbow
#

is there any other way to do this question?

willow skiff
#

you can at most eliminate options a and b, cause the answer will be positive and those options give a negative answer

#

and then it happens that option d is always greater than 1, use calculus or something
but 2 cos(A/2) < 2 cos(120/2) = 1

#

I think it's more trouble to do it this way than knowing how to simplify the given expressions

#

but if you are smart you can eliminate options quickly

quasi elbow
#

what do i need to learn before solving such type of questions? i think it does not really fall under the "half angle formulae" category and they have started by doing the questions itself rather than providing the concept(s)

willow skiff
#

here u = A/2 cause we use the double angle identity on sin A

#

and I mean why wouldn't you try u = A/2 if you want cos A/2

quasi elbow
#

i mean i get you but

#

when i first looked at the question, my first thought was not to start with the thing written on the top right

willow skiff
#

it's worth simplifying one of the options since they are all so similar

#

these are just test-taking techniques

#

cause JEE and everything

#

not to do with actual maths in my opinion

quasi elbow
#

so, hypothetically, what if we chose option d then?

#

like how are we supposed to know which option to start with?

willow skiff
obsidian monolithBOT
#

higher's secret twin brother

quasi elbow
#

i see

willow skiff
#

it doesn't matter which option you pick to start with

#

they're all nearlythe same

quasi elbow
#

yeah but you gotta choose one option

#

and you do not have time to pick a wrong one in the exam

willow skiff
#

so you choose all of them at once

#

if you get what I mean

quasi elbow
#

i do not

#

but yes, sort of

#

thank you though

willow skiff
#

np!

cyan cairn
#

valsl

warped shuttle
#

how can i find how many real roots does this have ?
(x^2 - 2)^2 - 9x^2 + 32 = 0

viscid thistle
#

you'll get x^4 + something * x^2

#

then u can just make a new variable y, and say that y=x^2, make a new equation in terms of y and it will be in the quadratic form and u can just use the discriminant

viscid thistle
#

then find the solutions of this quadratic

#

you will be left with r^2 -2 = 1st root , r^2-2 = 2nd root
not you have 2 other quadratic

#

solve :))

#

if b^2 - 4ac < 0 then the whole quadratic doesn't have any real roots and on the other case
b^2-4ac >=0 we have the roots as real

#

DANG!

#

i would have never got this idea when i was in high school

#

it is correct, right ?

#

nvm
plex idea was way simpler

warped shuttle
#

now what, desmos shows there are 4 roots

#

ok nvm i thing i got it

winter comet
warped shuttle
#

thanks

winter comet
#

xD

warped shuttle
#

i forgot t was x^2 lmfao

#

is there a faster way to determine only the number of roots ? cause expanding and solving for t takes time and it gives the values which i don't need

warped shuttle
#

how many roots does ... have

daring tapir
winter comet
#

there could be repeated roots

#

or imaginary roots

#

if those still count as roots then i guess yeah

daring tapir
daring tapir
winter comet
#

oh

daring tapir
#

Mmm

winter comet
#

if it changes i guess

daring tapir
#

So like (x-1)^3 p(x)

#

In an expanded form

winter comet
#

i mean

daring tapir
winter comet
#

it switches, andt hen it switches again

#

so it just keeps going

#

cuz the number of repeated roots is odd

daring tapir
#

Change that to (x-1)^4 then

#

Howll you predict that one?

winter comet
#

then it would switch an even number of times

#

so it would switch

#

like if it was going up, now it'll go down

#

at x=1

daring tapir
#

It switches similarly

winter comet
#

;l

daring tapir
#

,w graph (x-1)⁴

obsidian monolithBOT
winter comet
#

yea it switches at x=1

daring tapir
#

,w graph (1-x)^2

obsidian monolithBOT
winter comet
#

also switches at x=1

#

:(

daring tapir
#

Nvm

winter comet
#

maybe concavity?

daring tapir
#

At this point itd be faster for them to just find all the roots lol

winter comet
#

more concavity -> wider curve mebbe?

daring tapir
winter comet
#

such great idea

daring tapir
#

Lets graph the derivatives

winter comet
#

💀

daring tapir
#

,w graph 4(x-1)^3

winter comet
#

bro forgot the "graph" part

obsidian monolithBOT
daring tapir
#

,w graph 2(x-1)

obsidian monolithBOT
daring tapir
#

Argh

winter comet
#

concavity is increasing

#

wait a minute...

daring tapir
#

,w graph 6(x-1)^5

obsidian monolithBOT
daring tapir
#

I cant tell the power 3 and 5 ones apart

#

So kinda useless ig

daring tapir
daring tapir
winter comet
daring tapir
winter comet
#

ssuuuuuree blobwg '

river drift
#

curvature of a curve $y = f(x)$ is [ \kappa = \frac{\abs{f''(x)}}{(1 + [f'(x)]^2)^{3/2}} ] the radius of the osculating circle is the inverse of curvature [ R = \frac 1\kappa = \frac{(1 + [f'(x)]^2)^{3/2}}{\abs{f''(x)}} ] which is probably what you would think of as a measure of ``fatness''

obsidian monolithBOT
winter comet
river drift
#

well concavity gives you (twice) the leading term of the 2nd order taylor polynomial (basically the "tangent parabola") whereas the osculating circle gives you the radius of the osculating circle (basically the "tangent circle"). so both of them, in some sense, are the next level up from the "slope of the tangent line"

winter comet
#

ohh yea that makes sense actually 😂

#

probably curvature is more accurate then

simple scroll
#

hey can someone help me understand factoring?

#

i get it, but the questions they ask me on khan academy

#

I don't understand

dark acorn
#

-1-1 isnt 0, therefore it can fit in the denom

#

i think

#

right

#

x can be 0 tho

simple scroll
dark acorn
# simple scroll Can u explain?

that was wrong, basically the denominator cant equal 0 at any step in your simplification, thats where the restrictions come from

#

basically, x^2-1=/0 and x-1=/0

#

find values for x that make those equations equal 0 and those are your restrictions, aoi messed up by saying x=/0, when it can

#

so the answer for that problem is C i believe

dark acorn
#

no x cannot equal 0

simple scroll
#

Oh sorry 😭

#

I read it like that that

dark acorn
#

≠ this thing

#

loll

#

all good

simple scroll
dark acorn
#

x^2-1≠0, x-1≠0

dark acorn
#

yea

simple scroll
#

Hold on can I send another problem and maybe I can understand?

#

I still don’t feel like I’m getting it

dark acorn
#

yes go ahead

simple scroll
#

Ty

dark acorn
#

ok

simple scroll
#

soo like.. please break this down for me

dark acorn
#

she didnt state her restrictions

#

the simplification is correct

#

or wait nvm

simple scroll
#

can you explain the restrictions?

dark acorn
#

hold on sorry lemme look again

#

ok yeah

#

im pretty sure she just factored the numerator wrong

#

(x+2)(x-2)= x^2-4

simple scroll
dark acorn
#

its a difference of two squares

simple scroll
#

oh it has to be two negative two's

dark acorn
#

uhmm

#

wdym

#

nvm yeah i think it does

#

it should be (x-2)^2

#

or (x-2)(x-2)

#

sorry its been a minute since ive done these😭

simple scroll
#

It’s okay

#

I don’t understand what they mean by excluding this number, not excluding that number, etc

dark acorn
#

because if you put 0 in, the denominator would equal 0 and dividing by 0 is undefined

simple scroll
#

not saying that's your problem

#

but it's just making things more difficult for me to understand

dark acorn
#

ok lemme write this out rq

simple scroll
#

okay

dark acorn
#

its hard to explain over discord like this

wraith void
dark acorn
dark acorn
simple scroll
simple scroll
# dark acorn

also yeah subtracting 2 and 4 by themselves is gonna give them 0

#

what is that to prove?

dark acorn
#

restrictions only apply to the denominator

#

the numerator can be 0

simple scroll
# dark acorn wdym

oh sorry I was looking at the numerator and denominator at the same time

dark acorn
#

all good

simple scroll
dark acorn
#

0/x is just 0

#

or 0/ any number

simple scroll
#

so undefined or still not equal to 0?

dark acorn
#

no undefined is seperate

#

thats why the denom cant be 0, when the numerator can

#

if im understanding your question right

simple scroll
#

yeah

#

so if it cannot equal to 0

#

wait okay

#

so if you cancel out, right?

#

its like canceling them out, if you were to divide them, it would be equal to 1

#

so is that another way of saying whatever you factored out cannot be 1 either?

dark acorn
#

hmm

#

idk if id put it that way

#

unless im misunderstanding

#

if the denominator is 1-x, what can x not be

simple scroll
#

ig 1?

dark acorn
#

thats how i think about restrictions

#

what value of x would make the denominator equal 0

simple scroll
#

so if the numerator is 0, then it's 0

#

if the denominator is 0, undefined?

dark acorn
#

yes

#

not the restriction

#

the whole fraction

simple scroll
#

this is so confusing

#

i feel like dying

dark acorn
#

😭

#

ok so, the restriction is the value of x that causes the fraction to become undefined, or what causes the denominator to equal 0

broken heron
#

What's a restriction

#

Oh wait this is precalc

#

I'm in alg 2

dark acorn
tame pike
dark acorn
warm relic
#

Does anyone know what this is? I can't find a good video to explain it

still laurel
#

Anyone pls help T_T

willow skiff
#

so $\sec^2 x = \frac{1}{\cos^2 x}$ and so on

obsidian monolithBOT
#

higher's secret twin brother

willow skiff
#

This trigonometry video tutorial explains how to use reference angles to evaluate trigonometric functions such as sine, cosine, tangent, secant, cosecant, and cotangent with positive and negative angles in radians and degrees.. You need to have a good understanding of right triangle trigonometry, SOHCAHTOA, 30-60-90 triangle and the 45-45-90 tr...

▶ Play video
willow skiff
uneven nexus
#

What's wrong with this way

#

I got infty by this way

willow skiff
#

here you have a $0 \times (-\infty)$ form, so that is undefined

obsidian monolithBOT
#

higher's secret twin brother

willow skiff
#

for example, take $\frac{1}{n} \cdot n$ and $\frac{1}{2n} \cdot n$ as $n \to \infty$

obsidian monolithBOT
#

higher's secret twin brother

uneven nexus
#

Ooh

willow skiff
#

there are multiple ways to approach the question, of course LH is possible

#

(infinity/infinity) works for LH too

#

or you could split the numerator as $\ln(e^{2n}) + \ln(1 + e^{-2n})$

and $\ln(1 + e^{-2n}) \approx e^{-2n}$ as $e^{-2n} \to 0$ by Maclaurin series

obsidian monolithBOT
#

higher's secret twin brother

uneven nexus
#

Brilliant! Thx

willow skiff
#

nwnw!

tame pine
#

Yo

#

southy

warped shuttle
#

how to approach this question ?
in the sequence 1,4,7,10,... what's the minimum amount of elements we need to add that starts with the first element until the sum is bigger than 400 ?

so it means something like this
a1 + a1 + a2 + a1 + a2 + a3 ... > 400
which means
S1 + S2 + S3 + ... + Sn > 400

willow skiff
tame pine
#

Yo bro

#

Imma come after some time

#

Ok doing an assignment

quasi elbow
quasi elbow
agile sparrow
quasi elbow
tame pine
#

Where are my bros

drifting crag
drifting crag
quasi elbow
tawdry pilot
#

i’ve never seen something like that

#

maybe it’s trying to say beta / (n-1)

agile sparrow
quasi elbow
# tawdry pilot a typo maybe

I just checked again from another website and it's simply (n-1).beta; I do not know why would they write it like that though

quasi elbow
quasi elbow
#

how did we get the second step of this?

willow skiff
#

oh wait they didn't use that they just observed that cos 60 = 1/2

quasi elbow
#

i got it, thank you!

daring tapir
#

But sin160 = sin20

#

So this is just 1/8

#

This * cos60

#

Gave 1/16

#

Just an alternate solution

quasi elbow
#

makes sense, thank you so much

quasi elbow
daring tapir
obsidian monolithBOT
#

Ender Doesn't Mind
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

quasi elbow
#

thank you!

daring tapir
#

True

#

Its saved my ass more times than i can remember

quasi elbow
#

are we supposed to solve it like this or no? if yes, how do I proceed further?

viscid thistle
quasi elbow
#

i do not know how that will help though

#

i tried this: