#help-28

1 messages · Page 261 of 1

unreal wren
#

For broken string, what is the row total?

hard wasp
#

100

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68.70 of the total guitars had broken string

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@unreal wren am i wrong?

hard wasp
unreal wren
#

Sorry, I was busy blobcry

hard wasp
#

oh its okay

#

help me when youre free please

unreal wren
#

Yes I'm reading this again rn

hard wasp
#

okay

unreal wren
#

Suppose that acoustic broken strings = Z

#

We want to find Z

hard wasp
#

okay

unreal wren
#

Z is 61.11% of row total

hard wasp
#

61.11%

#

yeah

unreal wren
#

And we can figure out row total based on Z

#

What is the row total in terms of z?

hard wasp
#

idk

#

i dont understand

unreal wren
#

Hold up

#

Row total in terms of Z =??

hard wasp
#

z+70?

unreal wren
#

Yeah

#

And z is 61.11% of the row total

#

You can use algebra to find Z and the row total for broken string

hard wasp
#

what is row total though? 100 or 68.70?

unreal wren
hard wasp
#

wait

#

how do we calculate z?

unreal wren
hard wasp
#

please guide me step by step its very confusing for me idk why, i am not stupid but still its confusing for me

unreal wren
#

61.11% of (Z + 70) = Z

hard wasp
#

okay hear me first

#

61.11% of the guitars that had broken string were acoustic, right?

#

then

hard wasp
#

suppose guitars that were acoustic and had broken string is Z

#

then Z+70 guitars had broken strings?

unreal wren
#

Yeah 😭

#

Its basically common sense (not to be insultful)

hard wasp
#

oh okay i get it

hard wasp
unreal wren
#

Just use some basic alg to solve for z

#

Once you know z, you can also figure out the column total and total easily

hard wasp
#

z=110?

unreal wren
#

Lemme check

#

Yess

#

Then, you should be able to figure out the column total too

#

It's basic addition catthumbsup

hard wasp
#

131 yeah

unreal wren
#

Then figuring out the total of every thing is easy too

hard wasp
#

yeah filled the table

unreal wren
#

Can you solve for x now?

hard wasp
#

is it

#

x% of 131 = 82?

unreal wren
#

What

#

To get things straight, x is the acoustic neck repair column percent

#

X = $\frac{acoustic neck repair}{column total}$

glossy valveBOT
#

Matcha

unreal wren
#

But in percent

#

I keep on seeing you type but you haven't sent anything

hard wasp
#

i am confused

#

you wait

#

listen me

#

x% of the guitars that are acoustic had neck repair

#

and the number of acoustic guitars are 131

unreal wren
#

Yes

hard wasp
#

so x% of 131 = 21?

unreal wren
#

Or, x = 21/131

hard wasp
unreal wren
hard wasp
#

yayyy thank you so much

unreal wren
#

Your welcome

#

Khan Academy I c

hard wasp
#

how?

unreal wren
hard wasp
#

where did you see

unreal wren
hard wasp
#

ohh

#

okay but they dont ask the question related to what they teach

unreal wren
hard wasp
#

easy questions they discuss

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and ask difficult questions

unreal wren
#

I also suffered that when I used it to study

#

It's also a matter of things looking easier when you are presented the solution than when you are asked to find the solution, i.e. it's psychological related too

hard wasp
unreal wren
unreal wren
hard wasp
# unreal wren ?

the questions that are presented is actually easy in khan academy but the question they give us to solvee is difficult

#

i also dont like statistics and all

unreal wren
hard wasp
#

i am learning it for data science

unreal wren
#

This is still the easy bit of statistics tbh

hard wasp
unreal wren
#

The other units are more complicated but less confusing tho

#

I also found this topic, row and column percent, quite confusing

#

It was harder than the more advanced topics 💀

hard wasp
#

i like statistics but i dont like whatever this is, i have studied statistics before

hard wasp
#

in my university

#

and also my friend who is studying actuarial science said me to leave this topic 😭

unreal wren
#

Well, if you don't have any more questions you should type ".close"

#

It was fun helping you out catthumbsup

hard wasp
#

yeah it was fun taking help from you

#

next time i will tag you

#

hehe

#

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torn jolt
#

yoo

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torn jolt
#

@slate glacier

#

lets start

slate glacier
#

Alright

torn jolt
#

its abt enlargement

#

dyk it?

#

i want help with multiple questions of it

supple bloom
slate glacier
#

I'm not sure, can you send the question

torn jolt
#

this one doctor

slate glacier
#

There's a mod here you idiot

supple bloom
#

people can gauge if they can help you after you send the question

supple bloom
torn jolt
supple bloom
#

I just wanted to check you'd found your way to a new channel okay, but alright

torn jolt
slate glacier
#

Not sure, I can do it but not in the traditional way, I'm not familiar with it

#

You can wait for another helper, not something I'm familiar with unfortunately

torn jolt
#

ok

#

its alr

brave ruin
# torn jolt this one doctor

Polygon with 5 sides is called pentagon, 6 sides - hexagon, 7 sides - heptagon, 8 sides - octagon, 9 sides - nonagon, 10 sides - decagon

Can you now do i?

#

The shape is a polygon of some number of sides, count the sides and name it.

slate glacier
#

I feel like he needs help with the second part

brave ruin
#

To enlarge it by factor of 2 means to make another similar shape on the grid whose each side's length is 2 times larger than the original shape's corresponding side's length.

#

So like find length of each side, and multiply the side length by 2 so that now you have measure of each side of the new shape that you need to draw. Just draw it accordingly on the grid with the new measurements.

full forumBOT
#

@torn jolt Has your question been resolved?

white cave
#

Hello Everyone

#

star is pentagone?

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#
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full forumBOT
#

Please don't occupy multiple help channels.

swift canyon
#

<@&268886789983436800>

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proven lynx
#

"Now calculate the probability that the random values lie within one standard deviation of the expected value

proven lynx
#

so i dont understand the P( < x < ) part

#

what

whole dagger
#

umh

#

i'm trying to

#

i can't explain this

proven lynx
#

oh

#

<@&286206848099549185>

full forumBOT
#

@proven lynx Has your question been resolved?

languid junco
proven lynx
#

this

languid junco
#

"within one standard deviation of the expected value" means that |X - mean| < standard deviation

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if you remove the absolute values and solve for X, you get that inequality

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mean - SD < X < mean + SD

proven lynx
#

wdym X- mean

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oh

#

u mean the expected value

proven lynx
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meager spire
#

A farmer encloses a rectangular field by fences into eight smaller identical rectangles in an arrangement of two rectangles by four rectangles. He has 600 feet of fencing to build the enclosure and divisions. What is the maximum area of the field? What are the dimensions
of the field with maximum area?

meager spire
#

Nothing, I understand I have to use length and width to make an equation but I'm stilll confused as to how

main vault
#

call the length of one enclosure x and the width y

sonic stratus
#

Quick question, do the division share sides or there is a gap between each one?

meager spire
#

they share sides

uneven birch
#

Try drawing it, labelling sides and seeing if you can count the feet of fence he needs

sonic stratus
#

so, you basically have this figure

meager spire
#

yes

sonic stratus
#

Could you identify useful measures for this figure?

#

as to make an equation based on them

meager spire
#

length and width

sonic stratus
#

Theres multiple options for length or width, you could measure the total length and width of all pens together, or the individual sides

#

try to be a lil bit more specific

plush egret
#

Do you see how the whole shape is made up of little 'sticks'?

#

like, we have short sticks, and long sticks

sonic stratus
plush egret
meager spire
#

Yes, would I just be looking for the length and width of one rectangle to get the area

plush egret
plush egret
#

you said length, and width

meager spire
#

no yeah

#

okay

plush egret
#

maybe we can talk about length and width, in terms of long or short sides

#

hope that is helpful blobsweat you'll have to say if I confused it more

meager spire
#

no, it makes sense,, but how would I use the given information like the 600ft of fencing

plush egret
#

they're made up of fence

sonic stratus
#

the 600ft of fencing is all the fence you got

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IF you use less youre clearly losing area

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and you cant use more

plush egret
#

so if we take all of the short sides, and all the long sides, and put them together, we should get 600 ft

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That's one equation you can start with

plush egret
#

we can draw it more uneven if it helps to count

meager spire
#

would it be 5w * 4l = 600ft ?

#

actually no

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10w * 8l = 600ft because I only counted half of the full thing

sonic stratus
#

Consider that here we are working with lengths

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A length * a length = area

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Which isnt what we are looking for just now

plush egret
#

here I marked out 4 short

sonic stratus
plush egret
#

I think you're right there are 10 short sides in the shape

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I guess you end up with bigger coefficients

sonic stratus
plush egret
#

but its fine

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sure

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5 short

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3 long

plush egret
sonic stratus
#

and just in case

plush egret
#

really you'll get the same answer either way, all thats important is we have a way to count all of the length

sonic stratus
#

its just that the full w and l make it easier to calculate the area.

sonic stratus
meager spire
#

Im confused lol, so am I getting 3w x 5l = 600ft?

sonic stratus
#

so close

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again, the width and length are also measured in ft

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but the result is not square feet.

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If i tell you one of these lines has a length of 20

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What will be the total length of the three together?

meager spire
#

60

sonic stratus
#

How you came to that conclussion?

meager spire
#

I multiplied it by 3 ...

sonic stratus
#

and what about these 5?, suppose they measure 10

meager spire
#

LOL im so sorry, I actually have to go now I have a lecture is in 15 min

#

its 50 tho right?

sonic stratus
#

yes

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So, what will be the combined of these two by themselves?

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Again, you just stated the left part adds to 60, and the right part to 50.

meager spire
#

110

sonic stratus
meager spire
#

Yeah, I'm starting to get it

sonic stratus
#

lengths are additive

#

So you instead get 3w + 5l = 600

meager spire
#

right, okay

#

.close

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fallen ivy
#

In this week we'll be learning about parabolas, are they difficult? can anyone give me an example of a question?

unreal wren
#

Not everyone in the world goes through the same curriculum

full forumBOT
#

@fallen ivy Has your question been resolved?

wide sundial
#

There are a lot of interesting stuff about parabolas there’s a lot of theory

#

They are all relatively simple to understand on their own but there’s much to cover

fallen ivy
#

example?

little steppe
#

this is actually a decent use of chatgpt, a "generate example problems"

#

don't actually use it to solve problems but it's decently good at generating them

bright bronze
little steppe
#

right don't use it to solve problems

#

but it could give you ideas of what kinds you might encounetr

bright bronze
#

considering how op would do anything but open their textbooks, seems like good idea

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@fallen ivy Has your question been resolved?

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deep ledge
#

.close

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deep ledge
#

i need help

#

.close

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#
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deep ledge
#

need help with this

#

it to hard

vestal kindle
#

😭😭

deep ledge
#

what

#

<@&286206848099549185>

chrome canyon
#

what divided by 5 gives 10 @deep ledge

deep ledge
#

uhm

chrome canyon
#

also use the data given in the qn

deep ledge
#

can i use my calculator

chrome canyon
#

its not a unsolvable qn

deep ledge
#

oh

chrome canyon
#

tell man if i multiply 5 and 10 i get 50?

deep ledge
#

okay

chrome canyon
#

now if i divide 50 by 5 what do i get?

deep ledge
#

10

#

do i put 50 in the answer box

chrome canyon
#

why such confusion in the first place tbh

deep ledge
#

idk but im 15 so my mom yells at me everytime i get an answer worng

#

so i get kinda scared

deep ledge
#

what

chrome canyon
#

U R 15???

deep ledge
#

yeah

#

so

azure onyx
#

hang on, I think the channel is closed.

#

reopen the channel if you want to continue, OP.

brittle sun
#

.reopen

full forumBOT
brittle sun
chrome canyon
# deep ledge so

man these calculations are expected to b handled from a 6-7 yr old

deep ledge
#

bro

azure onyx
#

so does OP have any other question?

brittle sun
deep ledge
#

bruh im leaving

#

.close

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#
Channel closed

Closed by @deep ledge

Use .reopen if this was a mistake.

deep ledge
#

.close

brittle sun
#

It's closed dw

azure onyx
#

you already closed it.

brittle sun
#

If you have another question, feel free to reopen

deep ledge
#

well im sorry imma ask my friend to help me then

brittle sun
#

And it's okay to be behind, we all do things at our own pace.

brittle sun
deep ledge
#

arl

brittle sun
#

On behalf of that other user, I apologise

deep ledge
#

okay

brittle sun
#

Feel free to reopen and post another question if you have one

#

Also hullo Hyacine, sorry for jumping in out of nowhere

deep ledge
#

i only have 12 questions left

azure onyx
#

regardless, if you have a legit question, you deserve to be heard.

deep ledge
#

ok

brittle sun
#

Reopen then?

deep ledge
#

arl .open

brittle sun
#

.reopen

deep ledge
#

.reopen

full forumBOT
brittle sun
#

I'm gonna go swimming, so all yours @azure onyx

#

Feel free to tag me to pin stuff though

deep ledge
#

ok

azure onyx
#

I'll be watching, but in case you do have a new question, you can slap it here first, and I'll reply ASAP.

deep ledge
#

arl

brittle sun
deep ledge
#

is it 10

azure onyx
#

yes!

deep ledge
azure onyx
#

okay, this requires knowing how to round numbers.

deep ledge
#

ok

azure onyx
#

have you heard of statements like, "this thing costs $9.50, might as well cost $10"?

#

oops, ignore that bot.

deep ledge
#

ok

azure onyx
#

this is an example of rounding in action. we round to make calculations simpler to handle.

#

so here, you are told to round to the nearest ten. do you know what that means?

deep ledge
#

no

#

wait i think i know it

azure onyx
#

oh? let's hear it. can you round, say, 37 to the nearest ten?

deep ledge
#

2905

azure onyx
#

hm? is this the answer to the problem?

deep ledge
#

yeah this one

azure onyx
#

unfortunately, your answer is too correct for the question.

deep ledge
#

i got it

azure onyx
#

while 35 * 83 is indeed 2905, they want you to round the two numbers first, then multiply them.

deep ledge
#

yay

azure onyx
deep ledge
#

ok

#

brb gotta use the bathroom

azure onyx
#

so first, we have to round 35 and 83 to the nearest ten. this means that you will end up with two numbers ending in 0. round 35 first; what do you get?

deep ledge
#

i got 2905

#

heres my next question

azure onyx
azure onyx
deep ledge
#

ok

#

can i use my calculator

azure onyx
#

that defeats the purpose of learning how to round, doesn't it? I know you did it for the last question, but if you use it for questions like these before learning the concepts, you're not learning what's happening.

#

the idea is that we want to first know why one answer gives a better estimate than the other.

deep ledge
#

idk i just want to go to college...

azure onyx
#

not to belittle or anything, but that's exactly why you should get the basics down.

deep ledge
#

ok

azure onyx
#

sure, you can blaze through these questions with a calculator no problem. but are you learning the concepts behind them?

deep ledge
#

wdym

azure onyx
#

for instance, the previous question. do you know why 2905 is not the right answer?

deep ledge
#

why

azure onyx
#

you are told to round the two numbers to the nearest ten before multiplying. so your answer should end in two zeroes, definitely not a 5. the problem is that you ignored the instructions telling you to round the numbers and calculated them directly.

deep ledge
#

oh

azure onyx
#

that's why I said your answer was too correct.

deep ledge
#

oh

azure onyx
#

they want you to estimate the answer by rounding, not to use a calculator. if you have a calculator, you don't need to round!

deep ledge
#

oh okay

#

im dumb

azure onyx
#

(of course, if the numbers are still hard after rounding, that's fair game. but round first!)

#

so do you want to go back to the previous question, or stick on with this one anyway?

deep ledge
#

go back the previous question

azure onyx
#

alright, let's do it properly this time.

deep ledge
#

ok

#

i feel like im putting preasure on me

azure onyx
#

first, a quick idea on what rounding is. rounding is the process of approximating a number (or in simple speak, the process of turning a number into something that is "close enough").

#

for example, suppose a product is 37 bucks. if you're asked to find the total value of, say, 50 of them, this is ugly math.

deep ledge
#

ok

azure onyx
#

but instead, you can estimate the number by rounding the price of the product to, say, 40 bucks. now that's a nicer number we can deal with.

deep ledge
#

ok

azure onyx
#

this is called rounding, and this specifically is rounding to the nearest ten (because after the rounding, notice that the last digit is 0).

deep ledge
#

ok

azure onyx
#

so going back to the prev. question. one of the two numbers is 83. what would you round it to?

deep ledge
#

okay

azure onyx
#

(remember: nearest ten, so the number should end in a 0.)

deep ledge
#

okay so

#

2900

azure onyx
#

no, don't round the final answer. round the numbers individually first!

deep ledge
#

ok

azure onyx
deep ledge
#

round it to 35?

azure onyx
#

that's too far a round, plus it doesn't end in 0.

deep ledge
#

ok

azure onyx
#

I'll give you two choices: 80 or 90. which would it be?

deep ledge
#

90

azure onyx
#

is 83 closer to 90 than 80?

deep ledge
#

wait no it 80

azure onyx
#

good!

#

now, round 35 in the same fashion.

deep ledge
azure onyx
#

which is closer: 30 or 40?

deep ledge
#

40

azure onyx
#

excellent.

#

so now, 35 becomes 40 and 83 becomes 80.

deep ledge
#

ok

azure onyx
#

your multiplication thus becomes 40 * 80. what is the answer to this? you'll find that it is very different from the 2900 you've been insisting on.

deep ledge
#

wdym insisting

azure onyx
# deep ledge

you kept telling me and showing me 2900. the final answer isn't 2900 for reasons you'll see when you answer the last question I posed.

deep ledge
#

ok

#

why are my photos i sent pinned

azure onyx
#

because they relate to your question and helps helpers find your original question faster.

deep ledge
#

ok

azure onyx
deep ledge
#

so multiply 40 and 80

azure onyx
#

yes.

deep ledge
#

well they have 0 so im guessing it 0

azure onyx
#

sure? you can check with your calculator for this one, because it sure isn't 0 (neither 40 or 80 is 0, so).

deep ledge
#

oh it not

azure onyx
#

a product is only 0 if either number is exactly 0.

deep ledge
#

ok

azure onyx
#

so your answer is...?

deep ledge
#

3200

azure onyx
#

and that is the correct answer for that question.

deep ledge
#

10 more questions to go

azure onyx
#

sure. which one next? the one you sent earlier with the division question?

deep ledge
#

it different

azure onyx
#

sure. send it.

deep ledge
#

wait no it is

azure onyx
# deep ledge

you sent it already, which was why I asked if it was this one.

#

but either way, let's work on it.

deep ledge
#

oh okay

azure onyx
#

so, the question is just a long way of asking you which expression is wrongly rounded.

deep ledge
#

ok

azure onyx
#

that is, which expression has numbers rounded too far?

deep ledge
#

the second one

azure onyx
#

correct. so the one with the better estimate is the other one.

#

because rounding too far makes your estimate nonsense.

deep ledge
#

okay so estimate 800 and 40

azure onyx
#

now, you may use your calculator to divide the first expression.

deep ledge
#

gtg

#

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upper silo
#

how do you draw in th 3rd bound?

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upper silo
#

sorry its a little hard for me to see

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fair oracle
#

@upper silo

#

Can you draw |x + y| = 1, and |x + y| = 2 seperately?

upper silo
#

not sure if its right\

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thick hedge
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onyx glen
#

didn't you come here with this exact problem some time ago

thick hedge
#

I have a quiz tomorrow, so just reivsing kind of problems I stuggled with earlier

onyx glen
thick hedge
#

oh, okay

onyx glen
#

i distinctly remember it

thick hedge
#

so here all I need is the mariginal of Y, right

onyx glen
#

there are 2 routes:

  1. recognize X and Y are independent and just calculate P(X<=1/2)
  2. if you don't trust yourself with that, go by the definition the "honest way": P(X<=1/2 & Y>=3/4) / P(Y>=3/4), calculating each one with an integral
thick hedge
#

I'll do the 2nd

#

or wiat

#

*wait

#

yea, the mariganls are 2x, 2y

#

so just $\int_{0}^{1/2} 2xdx$

glossy valveBOT
thick hedge
#

so 1/4

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atomic hare
#

<@&268886789983436800> clean up thank you

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river goblet
#

can anyone show me how to do questions like these?

low sail
#

Do you know how to solve differential equations @river goblet

river goblet
#

roughly but im not very good at them

low sail
#

$$\frac{dy}{dx} - y = 1$$

glossy valveBOT
#

Adarsh

low sail
#

Does this help you? or give you any idea

river goblet
#

would it then just go to dy-y=1dx

low sail
#

$$dy - ydx = 1dx$$

river goblet
#

oh yeah

glossy valveBOT
#

Adarsh

low sail
#

If you do that it would be

#

Now you can take dx common on the RHS

river goblet
low sail
#

What do you mean?

#

$$dy = dx(1+y)$$

glossy valveBOT
#

Adarsh

low sail
#

This is what I meant

river goblet
low sail
#

Yes

#

Now you can divide both sides by 1+y then integrate both sides

river goblet
#

sorry im confused with how that rearangement works

low sail
#

From which part are you confused

river goblet
#

just in how it goes from this

river goblet
low sail
#

Do you agree that

low sail
#

$$\frac{dy}{dx} - y = 1$$

glossy valveBOT
#

Adarsh

river goblet
#

im not sure sorry

low sail
#

$$\frac{d(y(x))}{dx} - y(x) = 1$$

glossy valveBOT
#

Adarsh

low sail
#

Is this fine?

river goblet
#

so d/dx y(x) is equal to d(y(x))/dx?

#

theyre essentially the same thing?

low sail
#

In differential equations, yes

river goblet
#

okay i understand

river goblet
#

so then where, do you need the ys on one side and xs on the other?

low sail
#

Yea you want to seperate the vairables

#

You want dy with the ys and the dx with the x

river goblet
#

so gos to dy/(1+y)=dx?

low sail
#

Yes

river goblet
#

but does integratin not just then give y=x

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thick hedge
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thick hedge
#

This is what I have so far:

#

$X^2≥Y; X \sim UNIF[-1,1]; Y\sim UNIF[0,1]$\
So $X=1/2;Y=1$

wide sundial
#

\sim

glossy valveBOT
fast peak
#

X=1/2 ??

wide sundial
#

where did u get X^2 >= Y

restive geyser
# thick hedge

I'd first try to find what values X, Y result in the quadratic having real roots in the first place?

thick hedge
fast peak
#

well he did. he just skipped the step

#

cause...

#

who knows

restive geyser
#

ah he did yh

#

Okay, now this amounts to drawing the region of the rectangle [-1, 1] x [0,1] where that inequality holds

#

Then calculating what proportion of the rectangle that region is

thick hedge
#

The question I had is what's the joint PDF I'm integrating over here

fast peak
#

everything is uniform

restive geyser
#

You don't need a PDF here tho?

fast peak
#

the pdf is just 1/total area

thick hedge
#

is it 2/3

restive geyser
#

Independence allows us to do the joint thing in the first place; UNIF allows us to not worry about weighting

thick hedge
#

$\int_{-1}^{1} x^2dx$

glossy valveBOT
restive geyser
thick hedge
#

tq

restive geyser
fast peak
#

of course we still need weighting

#

that integral has area 2/3, sure

#

but the total area is 2

restive geyser
#

(if you really wanted tho, iirc the PDF of a UNIF[a, b] is something like 1/(b-a)?)

thick hedge
thick hedge
#

got it

#

tq

#

So $Y$'s PDF is $1$; $X's$ PDF given Y=y is $1/√y$

glossy valveBOT
thick hedge
#

is it just √y

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charred birch
#

is this vector field consercative

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@charred birch Has your question been resolved?

nova briar
#

Not if your contour is translated along the x axis
On the given contour, it looks like it though

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forest owl
#

Hey, I'm a bit lost on how/why they graphed f0(x) like this. Could someone explain how they did this?

olive olive
#

what must an odd function satisfy

forest owl
#

Oh right, f(-x)

#

Okay I see now lol

#

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languid junco
#

I would need to see the work, but i can already tell there's probably an issue since you should have an n in your sines and cosines somewhere 🤔

#

also what did you mean "pi/2 between pi/2 <t < pi"

forest raptor
#

i have a feeling i messed up rlly badly

languid junco
#

okay well your indefinite integral for bn was fine but you didn't evaluate the integral on your bounds

#

which explains why you have a t in your coefficients

#

you also forgot to include the second integral (the one from pi/2 to pi) in your final coefficient

forest raptor
#

Omg okay ill redo

languid junco
#

and thank you for having neat handwriting lol

forest raptor
#

i probably messed up again somewhere 😭 so sorry

languid junco
forest raptor
#

End me

#

Tysm

forest raptor
#

it cancelled out, hopefully its right now

#

wait no

#

i made maths up

#

they cannt cancel

#

this does tho, if im not wrong

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forest raptor
#

ty for your help

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radiant rampart
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radiant rampart
#

can anyone help me with this?

#

<@&286206848099549185>

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radiant rampart
#

ai helped me cuz yall be sleeping or sum 😢

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fierce roost
#

hii im so confused why is this wrong?

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fierce roost
#

the derivitive of the equation is -2t-5, right?

ebon fulcrum
#

Yes

fierce roost
#

and then plugging in 4 you get -13

#

and since its negative it's moving to the left

#

ok so then what am i doing wrong?

gritty rose
#

you put v(4) = 13

ebon fulcrum
#

You put 13

fierce roost
#

yes but it has the less than 0 after, right?

#

its 13 less than 0

gritty rose
#

wut

fierce roost
#

wait no you guys are right.

#

my logic is weird i fear

#

erm thank you guys have a wonderful night!

#

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thick hedge
#

Find the covariance of this dist

#

[
\begin{array}{c|ccc|c}
& X=1 & X=2 & X=3 & P(Y=y) \ \hline
Y=1 & \tfrac{1}{6} & 0 & 0 & \tfrac{1}{6} \[4pt]
Y=2 & 0 & \tfrac{1}{4} & \tfrac{1}{12} & \tfrac{1}{3} \[4pt]
Y=3 & \tfrac{1}{12} & \tfrac{1}{12} & \tfrac{1}{4} & \tfrac{5}{12} \ \hline
P(X=x) & \tfrac{1}{3} & \tfrac{1}{3} & \tfrac{1}{3} & 1
\end{array}
]

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thick hedge
#

oops

#

this is a mess

#

.close

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glossy valveBOT
#

lifehealer
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

#

lifehealer
Compile Error! Click the errors reaction for more information.
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jade owl
#

when graphing polar equations what would be like a "life hack" that would be really helpfull

craggy tapir
#

graphing polar equations is really no different from graphing cartesian equations, you memorize how common graphs look (circle, cardioids, lemniscate, etc.) and their respective equations, tweak the equation you need to graph into a combination of familiar graphs you can plot, and draw them

jade owl
#

ig without memorization theres no easy way

#

thanks tho

#

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craggy tapir
#

i mean, what easy way are you expecting? just like how you would shit your pants graphing (sin(x))^tan(y) = cos^2x, it's manual work if you can't break the equation down into smaller ones

umbral dome
#

if you can graph r vs theta on cartesian axes, you can generally figure out what the corresponding polar plot should look like from there

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tiny anvil
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tiny anvil
#

I don't get it

#

F(x) belongs to all real other than 1 right?

fathom saddle
#

That's the domain. x is in R - {1}

tiny anvil
#

I mean I understand the note point why it can't be 2 , but then how will I objectively find the sol^n without any help , I mean what kind of exception is this

onyx glen
#

also don't auto capitalize

fathom saddle
#

The range can't include 2. f(x) is in R - {2}

tiny anvil
#

Ehhh so this concept involves domains and ranges ?

#

God......

buoyant wadi
#

R - {1} is all possible inputs to f(x), R - {2} is all possible outputs of f(x)

onyx glen
#

and explicitly note when you have to divide by zero

tiny anvil
onyx glen
#

no not like that

tiny anvil
#

bruh

onyx glen
#

when you solve for x in terms of y

tiny anvil
#

X in terms of Y

#

got it

onyx glen
#

lowercase

tiny anvil
#

X/(x-1)=Y/2

#

Yea I am lost

onyx glen
#

LOWERCASE

tiny anvil
#

Omg

#

Sure

onyx glen
tiny anvil
#

Pls demonstrate btw

#

X=69X-69

onyx glen
#

LOWERCASE

tiny anvil
#

68X=69

#

I am sorry T_T

#

x=69/68

#

Habit

onyx glen
#

now do same magic with x/(x-1)=y/2

tiny anvil
#

ohhhh

#

I get it

#

x=2/(y-2)

#

so Y can't be 2

#

Now pls explain the general approach

#

I don't get it

buoyant wadi
#

You've essentially done the general approach

#

2x/(x-1) = y is "y in terms of x"

#

x = 2/(y-2) is "x in terms of y"

#

2x/(x-1) says x can't be 1, 2/(y-2) says y can't be 2

tiny anvil
#

Ehhh

#

so acc to question

#

what to find

#

ehhh

#

Like domain or range

onyx glen
tiny anvil
#

Oh I just got it

#

ty ya al

covert heath
#

...

tiny anvil
#

for being so nice ;)

#

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solid ruin
#

Given matrices A and B with LU decomposition $A=L_A U , B=L_BU$ prove/disprove that the row space of A is equal to the row space of B

glossy valveBOT
#

prograce

solid ruin
#

How do I start

#

I think its true

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#

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fast peak
#

when you do gaussian elimination on A, what does that tell you about the row space

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indigo tartan
#

The outline of an object can be approximated by a half ellipse with a semimajor axis of 200px and a semiminor axis of 312px

indigo tartan
#

When thwhen the curve is revolved about the xa xis find the resulting surface area

full whale
#

holy shit, you're still at it
you have mentioned enough terms to make me convinced that you know you need integration. have you... tried that?

indigo tartan
#

i know im just stuck

#

there was a command like

#

!status

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indigo tartan
#

i don't know where to begin to be honest

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lavish junco
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flint moon
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flint moon
#

i have been looking at this for like 15 mins and can't think of a relation which fits

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robust slate
#

Note that an integer $n$ belongs to the $k$th set iff $T_{k-1}<n \leq T_k$, where $T_k$ is the $k$th triangular number. From here, consider doing some floor/ceiling bounding stuff.

glossy valveBOT
#

Civil Service Pigeon

sonic stratus
# flint moon

For some work of mine, i personally did something relatively similar.

#

The line of thought of it is a bit abstract, but, its analog to the following problem.

#

Suppose you have n dots you wanna fit in the following structure:
What will be the lowest k st. the n dots will fit without leaving an empty column.

#

the sequence here is of the form: 2^k

#

So, you can solve as follows:

#

Now, in your sequence, the sequence k must look something like this:

#

From here the notion should be pretty easy, hope that somewhat helps.

sonic stratus
# sonic stratus

Also, as reference, you can use the floor ( log_2 n ) function as your relation

#

all n st. the result is = k_i are part of the same subset.

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@flint moon Has your question been resolved?

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torn jolt
#

yo

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torn jolt
#

for part e im not sure on how to solve for the solution vector in Ax=0

glacial pasture
#

x=z-5t
-2y+5z-6t=0, y=5/2 z - 3t
z,t free variables [from Bx=0]

from there you should be able to construct your generic null vector - and from that you can make your basis vectors

torn jolt
#

dude I have 0 idea what you just said

torn jolt
#

are we not solving for each unknown?

glacial pasture
#

we're finding a general null vector, so having unknowns is fine as we're looking at it in the form of a linear combination of the basis vectors
if we know the vectors have the form
[z-5t , 5/2 z-3t, z , t]
then thats the same as

z[1 , 5/2 , 1 , 0]+t[-5 , -3 , 0 , 1]
in which case what is our basis?

torn jolt
glacial pasture
#

z and t are x_3 and x_4

#

the only thing left to do from where I left it is to write the basis

torn jolt
glacial pasture
#

but you can plug it in to check

glacial pasture
torn jolt
#

why dont we do that when we have a plane or line as a solution

glacial pasture
#

thats essentially what I did, it just so happens that we have 2 free variables which is why we have a space

I set the vector to be [x,y,z,t]^T, multiplied it by B, and then solved for the variables

glacial pasture
torn jolt
#

like geometrically whats the point

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say you have 1 exact solution

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from 3 planes

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@glacial pasture did you change your mind?

#

maybe not

glacial pasture
#

its not that, Im just not great at explaining things in geometric terms

for a single solution of three planes, it would be the planes all intersecting in at one point, in which case we have a definite (x,y,z), no free variables

If we have one free variable, then we have a line - then our planes all intersect along a line e.g [t,2,t+3] is the line [0,2,3]+t[1,0,1]
if i found x=t, y=2, z=t+3

If we have two free variables then our solutions form a plane, so all our planes overlap

if we have 3 free variables then thats just all of R3

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@torn jolt Has your question been resolved?

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patent nebula
#

Can someone explain the answer

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craggy tapir
#

i don't see the answer

patent nebula
#

So basically i checked for the extraneous solution and it should
Root(49) =-7

#

It saids no real solution is it because
7= -7

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Or what

craggy tapir
#

i'm not sure i follow

#

where is the answer specifically?

zenith hinge
craggy tapir
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# zenith hinge

As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.

patent nebula
zenith hinge
#

yes

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no real sols

patent nebula
#

Alright

#

Thx

unique perch
#

notice 10-13r >= 0

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so r <= 10/13

#

but r>=4 at the same time so no real solutions

patent nebula
unique perch
#

does the problem require you to find complex roots?

patent nebula
#

Said to like find the value of n and check for extraneous solutions

unique perch
#

huh

#

that's weird as hell

unique perch
#

that's horribly inefficient

patent nebula
unique perch
#

that's a lot more work than just observe r >= 4 and r <= 10/13

patent nebula
#

Alright

#

.close

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stiff pier
#

<@&268886789983436800> not sure what this is but it seems fishy.

twilit leaf
#

probably cheating

#

yeah test proctors usually get the tests a day or two early and amc b is on the 13th

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twilit leaf
#

thank you lance lance, of lancesquaredland

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charred cedar
#

I'm not sure how to approach and solve this problem

nimble crane
#

drawing a few pictures might help catthink

sonic stratus
#

As long as you have some knowledge about functions

sonic stratus
#

Well, lets start with r as a function P -> P

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Do you understand what its essentially doing?

#

Beyond the description the problem gives

charred cedar
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it’s just a function r to P P is a subset of itself?

sonic stratus
#

From the fundamentals,
do you understand why functions are a special type of "relation"?
And what is a bijective function?

charred cedar
#

relations are just functions basically but with multiple input output can be repeated then bijective functions are those that are injective and subjective one to one and on to

sinful wind
#

hi?

sonic stratus
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# sinful wind hi?

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sinful wind
#

PT-BR people?

sonic stratus
#

Just to give a sense, a Relation (which can be between two sets), is basically a pairing between elements of the two.

charred cedar
#

sorry this was taught way back and I don’t have my notebook on me to properly define, I kind of just do the equations

sonic stratus
#

As a dumb example, lets say we do a relation between the set "fruits" and "colours"

We can say that "Apple" might be paired, to both Red And Green

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Well, a function is basically a Relation , but an element from the origin set can only have one pairing from the other set..

ember slate
charred cedar
sonic stratus
#

This section is telling you, element by element

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whats the origin, and whats the pairing.

charred cedar
#

yes

sonic stratus
#

So, for a function r(n)
a becomes b
b becomes c, etc...

charred cedar
#

yeah makes sense

sonic stratus
#

Doing some notation abuse, if you applied r to a whole set of elements a to e
{a,b,c,d,e}
it would become: {b,c,d,e,a}
again and its:{c,d,e,a,b}

#

So its basically cycling through the elements of the set.

#

We consider that idea a rotation, since, when applied multiple times, youll eventually get back to the original state.

sonic stratus
charred cedar
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tbh we didn’t learn this part

#

confused me a lot but that’s you this makes sense

sonic stratus
#

Visually it looks like this

charred cedar
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r(P) means rotation on set P?

sonic stratus
#

again, a bit of notation abuse

#

Just take it as applying r to all elements

charred cedar
#

okayy

sonic stratus
#

Arguably, from a theorical standpoint, these are arrays in reality

#

so order matters for our purposes

#

now, we define another function f_a P -> P

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Which is essentially a reflection instead of a rotation

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Its described as using a line from a to the perpendicular in cd

charred cedar
#

ohh

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can I know how it’s written the reflection?

#

so I know how to identify

charred cedar
sonic stratus
#

You get this

#

from the set meaning

#

You have to consider that rotations can alter the absolute order of the array

#

Meaning: b will always succed to the right a, c will always succed b, etc...

#

Well, reflection can change that order.

#

If we start from the rotation
$r: {(a,b),(b,c),(c,d),(d,e),(e,a)}$

glossy valveBOT
#

∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

sonic stratus
#

You get that, as we described, the array $\ {a,b,c,d,e}$ becomes
$\ {b,c,d,e,a}$

charred cedar
#

that’s the origin right?

glossy valveBOT
#

∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

sonic stratus
charred cedar
#

is this the rotation f_a

charred cedar
sonic stratus
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f_a is a reflection, right now im trying to note down how f_a doesnt work like r

charred cedar
#

oh so is this r(P)

#

ah gotcha

sonic stratus
#

$f_a$ instead has: ${(a,a),(b,e),(c,d),(d,c),(e,b)}$

glossy valveBOT
#

∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴

sonic stratus
charred cedar
#

yes I recall now sorry

sonic stratus
#

Since it always uses a as a reference

charred cedar
#

is the reference just another word for starting point?

sonic stratus
#

So its uses a and cd as its "frame", which, as we stated previously, the order cannot be changed by rotations

#

you can probably see that this arrangement is equal to applying r twice.

#

But the reflection f_a still retains its property of being a line from a to the perp. in cd

#

With "starting point" i meant the original arrangement from a to e.

#

Either from geometric reasoning, or set theoretic rational, you should be able to solve for the problem

charred cedar
#

thank you for the visuals as well, helps a lot

charred cedar
sonic stratus
#

if its helps you, both ways are valid

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1 its pretty easy to show from a set theoretic standpoint given some of the things i just said

charred cedar
#

yeah for sure

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@sonic stratus you're good with your wording I can probably figure it out but what is a) asking for?

sonic stratus
#

in human terms:

If you rotate and reflect, will you get the same as reflect and rotate

sonic stratus
#

go check on the diagram, draw in your own

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@charred cedar Has your question been resolved?

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crystal tree
#

Idk how to do this I fell asleep in class

onyx glen
#

cause rn im gonna presume that you grabbed sth off Google image search just to troll about "posting a hard question in help channels"

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@crystal tree Has your question been resolved?

torn jolt
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tidal storm
#

Very unsure as of what to do

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tidal storm
#

Obviously the quadratic residues mod 5 are 0, 1 & 4, but I’m unsure as of what to do next

#

I tried splitting up cases of the possible combinations which would create a Q which is divisible by 5 but there are too many cases

rapid rain
#

Since we're considering sets btw, order in which the numbers appear doesn't matter

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So 1112 and 1121 would count as the same instance

tidal storm
#

Oh wow already a mistake

tidal storm
tidal storm
#

Alright I’ll get back to you

#

If I counted correctly there should be 14 cases

#

I’m guessing from here we find the total number of possible cases

#

I’m inclined to say 5^4 but I think that would include permutations of the same set

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@tidal storm Has your question been resolved?

frigid carbon
tidal storm
#

I wrote 0 as in congruent to 0

#

Same for all the other numbers

#

Think I found a bit of a route for myself

#

There are only 3 possibilities of a Q which is divisible by 5

#

It depends on the congruency of the individual squares, so there are 3 cases:
#1: 0-0-0-0
#2: 1-4-1-4
#3: 0-0-1-4

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I think that if I’m able to calculate the total number of ways that each of these cases occur, then add them together, then finally divide them by the total number of possible choices of 4 numbers from N, I should get the result

#

Evidently the number of possible choices of 4 numbers from N is N choose 4.

#

Then based on N I can find how many numbers there are from 1 to N that have squares that are divisible by 5.

#

And also how many are congruent to 1 & 4 mod 5.