#help-49

1 messages · Page 175 of 1

cedar mason
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!occupied .

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cedar mason
#

also what.

dark locust
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dark wharf
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I need to find a counting problem that proves this combinatorical identity

lethal path
dark wharf
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That's what I thought but I have no idea how to prove the right hand side is a valid solution

lethal path
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you can choose 0 people from m people, then there is only one way to choose n + 1 people from n + 1 people

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or you could choose 1 person from m + 1 people, then there is also only one way to choose n people from n people

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the total number of people is always m + n + 1

dark wharf
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But then it's (m+1 choose 1) times (n choose n-1), isn't it? Because there are multiple ways to choose the n-1 people out of n

lethal path
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so you just divide them into two groups

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wait yeah there's +1 stuff going on

dark wharf
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After choosing the k people we are left to choose n-k out of n-m-k+1

lethal path
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and the total number of people you choose is 0 + (n + 1) = 1 + (n) + 2 + (n - 1) = ...

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ok fixed finally

dark wharf
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What do you mean the group is split into (m, n+1)?

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Like the big group is m and the small one is n+1?

lethal path
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like one group has m people and the other one has n + 1

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then that should imply the LHS is (m + n + 1)C(n + 1) no

dark wharf
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We want m+n+1 C n, not n+1

lethal path
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idk

dark wharf
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I understand your solution and I think it's very close but it needs to add one less person

lethal path
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yeah I hate combinatorial proofs

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hopefully you can spot where I've gone wrong and come up with the correct version

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misty laurel
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Hello, I would like to know if there is a way to create a formula to describe: (1/800)+(1/799)+(1/798)+(1/797)...+(1/n)

placid spoke
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there is not unfortunately

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approximations are the best we can do

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there's nothing closed form at least

misty laurel
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damn

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thank you tho

runic hamlet
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wdym with "formula"

misty laurel
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like a harmonic summation

lethal path
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no closed form

runic hamlet
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there is no "short" formula which you can enter into your calculator to "quickly" compute the value of the whole sum

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if thats what you mean

tired osprey
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It's approximately equal to ln(n) + euler mascharoni constant

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asymptotically* as n gets greater

sharp coral
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well depending on your definition of a closed form, it can be expressed using the euler-mascheroni constant and the digamma function

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but ofc neither of those are buttons on a typical calculator

misty laurel
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yea, I want to summarize it in a way that make calculating the answer easier (meaning I dont have to write individual parts of the summation ex: 1/800+1/799+1/798

tired osprey
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with approximations or an exact fraction?

placid spoke
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no way to get an exact answer without a lot of adding

misty laurel
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aproximation is also okay

tired osprey
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ln(n) + γ

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so 1/800 + 1/799 + ... + 1/1 is ln(800) + 0.57721..

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7,2618217277

misty laurel
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what does 0.57721 represents?

tired osprey
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the euler mascheroni constant.

misty laurel
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oh ok

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what if I want it to not be until 1/1 but 1/500 for ex

tired osprey
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first do the 1/800 + 1/799 + ... + 1/1 and then subtract 1/499 + 1/498 + ... + 1/1.

misty laurel
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ohhh okok

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how exact is the aproximate?

sharp coral
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,w sum from k = 500 to 800 of 1/k

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,w ln(800) - ln(500)

tired osprey
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lmao

misty laurel
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Is this another way of calculating ?

sharp coral
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it's the "exact result"

sharp coral
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so to answer your question it looks like you get 2 decimal places from that

misty laurel
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oh, so I can either use summation to find the exact no. or the euler's constant to finding an approximation (up to two decimal point)

tired osprey
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The bigger your n, how closer the approximations

sharp coral
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you can also add more terms to the approximation if you want more decimal places

misty laurel
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ok thank you

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sharp coral
misty laurel
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more terms for the constant right?

sharp coral
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more terms for the approximation. so a better approximation is γ + ln(n) + 1/(2n)

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and a better approximation than that is γ + ln(n) + 1/(2n) - 1/(12n^2) and so on for however many terms you're willing to use

misty laurel
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where is it ?

sharp coral
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bottom of "calculation"

tired osprey
misty laurel
#

kkk thank u

#

.close

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woeful turret
midnight plankBOT
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midnight plankBOT
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@woeful turret Has your question been resolved?

woeful turret
#

someone help

tidal turret
#

is O the centroid

midnight plankBOT
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@woeful turret Has your question been resolved?

midnight plankBOT
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@woeful turret Has your question been resolved?

woeful turret
#

<@&286206848099549185>

last slate
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I feel sorry for you

woeful turret
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😔

tawny apex
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uhh so first if we take 2 mirrors AB and AC

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by the formula, $n=theta/360$

grand pondBOT
tawny apex
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we can find the number of images formed, which would be 6

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and as it is an even number, we will subtract one

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giving us 5 images by 2 sides

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so similarly, each pair of sides will form 5 images each

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giving us 3*5=15 images

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but 3 of them will coincide, and thus there would be 12 images

midnight plankBOT
#

@woeful turret Has your question been resolved?

brave patio
woeful turret
woeful turret
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tranquil marsh
midnight plankBOT
tranquil marsh
#

Need help with part C. This is my work so far

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after thatt work i subbed in everything to that equation and got the wrong answer

final mural
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<@&286206848099549185> I am stuck aswell

jagged sandal
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!occupied

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hollow sigil
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pm

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Or sum for you

final mural
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wait sorry

hollow sigil
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.

final mural
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yes its 11:30

jagged sandal
final mural
hollow sigil
final mural
jagged sandal
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But let’s not talk in this channel

final mural
#

if we could

hollow sigil
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k bye

final mural
hollow sigil
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bro what

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y so mean? And I’m not fat

hollow sigil
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you sure about that?

remote tangle
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!topic

midnight plankBOT
#

Please read the channel description before posting, and stay on topic.

tranquil marsh
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could someone help me with the problem please ?

hollow sigil
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alr now don’t say crap again and let me leave u be with your math problem

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not you tweets

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the other dude

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Okay bye

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My apologies for interfering

jagged sandal
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@tranquil marsh Content-wise, I’m right behind you (I’m getting to the end of the Series megaunit. I should be at Parametric/Polar in a week or two)

final mural
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@jagged sandal we're trying to find the slope of just the x values but the question isnt accepting the values when plugging in the values for theta after deriving

tranquil marsh
jagged sandal
tranquil marsh
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we r doing the same hw its ok

final mural
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what if we're doing the same hw

jagged sandal
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@tranquil marsh I’m giving ~ ~ the benefit of the doubt by having you confirm; is what ~~ is saying true?

tranquil marsh
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Im confused

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yea we have the same hw

jagged sandal
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Huh…

tranquil marsh
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we have the same question essentially

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we both need the same help

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do u think u can help on the problem even tho if u still havent reached this unit yet ?

jagged sandal
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I’m going to pull up my textbook

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It might take a bit, but I could probably figure it out quickly

tranquil marsh
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Ok thanks its ok if you cant

jagged sandal
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I do know a little bit about Polar Coordinates thanks to University Physics I

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But I may need to understand it from a Calculus perspective

tranquil marsh
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ok

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if it helps i think youre basically implicitly deriving the polar to rectangular equations

jagged sandal
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I found the equation

tranquil marsh
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like the x=rcostheta equation is used i believe

jagged sandal
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I think

proper veldt
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Hi

jagged sandal
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Hello

tranquil marsh
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Hi did u see the problem i neededd help with ?

fickle oriole
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Sorry

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I figured it out

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I was struggling for 5 minutes

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Because I forgot to multiply by 5

tranquil marsh
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ooh

jagged sandal
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I’m actually going to stay so I can get a head start

fickle oriole
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🙏

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Ok I don’t remember the equation stuff they teach you

jagged sandal
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But maybe chime in every once in a while if I can

fickle oriole
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start with x=rcostheta right

tranquil marsh
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hold on ima resend my work so i can follow u

fickle oriole
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I think doing it like that is annoying

tranquil marsh
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yea i starteds with that and dervied with respect to t using the product rule in the first line of work, does that look good ?

tranquil marsh
fickle oriole
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what is x in terms of theta

jagged sandal
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Wait

tranquil marsh
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what do you mean ?

proper veldt
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Wheres the problem I might be able to help

tranquil marsh
fickle oriole
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rewrite x

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using x=rcostheta

jagged sandal
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$d\theta\divdt = 5$ right?

tranquil marsh
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dtheta/dt equals 5, not just dtheta

fickle oriole
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right

jagged sandal
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Sorry, I rushed to compile the teXit

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I’m new to it

fickle oriole
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right

proper veldt
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Is it the physics problem?

jagged sandal
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But, dtheta/dt = 5, right?

static plume
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let theta=k cuz can’t find symbol
x(t)=cos^2(k) + cos(k) * k,
so dx/dt=[-2cos(k)sin(k) + cos(k) + -sin(k) * k] dk/dt

fickle oriole
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hell nah cuh

static plume
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then plug in dk/dt and k

tranquil marsh
fickle oriole
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ye just do product rule now

tranquil marsh
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ok

fickle oriole
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with implicit diffirneation

tranquil marsh
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should we not get the same answer though ?

fickle oriole
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i didnt check ur work

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one sec

tranquil marsh
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ohh but now i wont have to solve for dr/dt

fickle oriole
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no

tranquil marsh
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i think what u did is right, i had to get rid of r early

fickle oriole
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i dont see a world

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where u could get the right answer

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with that

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answer is missing a pi

tranquil marsh
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LOL ok

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so with what u did now i wont have to solve for dr/dt

fickle oriole
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u dont need dr/dt

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like its there

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but u dont have to mention it

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here ill do the first part of product rule to show

tranquil marsh
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yea i just substitue the stuff they fave me in the question

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i understand i think

fickle oriole
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oops not 2theta

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just 2

tranquil marsh
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wait what ?

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i product ruled and got this LOL

fickle oriole
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what

tranquil marsh
fickle oriole
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yes

tranquil marsh
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I derived that

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and made 2theta and costheta my f(x) and g(x) that i was productt ruling

fickle oriole
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why did u factor a 2 out

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it will cancel out with the sqrt2/2

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from pi/3

tranquil marsh
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i just got rid of it before i did the product rule

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oh oops

fickle oriole
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3pi/4*

tranquil marsh
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is that math right though ?

fickle oriole
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ye

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i made the 2costhetasino

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into sin2theta

tranquil marsh
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oh ok

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am getting -18.73

fickle oriole
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ye

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thats right

tranquil marsh
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YES

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THANK U

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its right

tranquil marsh
#

.close

midnight plankBOT
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kind estuary
#

I have a problema at this exercise I tried to make all kind of transformarions and notations , I am stuck

kind estuary
#

Oh yeah

lyric charm
#

,rccw

grand pondBOT
lyric charm
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ok so

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you have rewritten the logarithmic equations there as $a^{4/3} = b$ and $c^{5/6} = d$, yes?

grand pondBOT
kind estuary
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Ok

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I have got to this but from now...

lyric charm
#

you can raise both sides ^3 on the first equation and ^6 on the second to get a^3 = b^4 and c^5 = d^6

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so you know a has to be a fourth power, and c a sixth power

zenith osprey
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Tbh this can only be solved by hit and trial

kind estuary
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Ok

zenith osprey
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Like we know b will be in some form of a^3k

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And d is c^6k

kind estuary
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Yeah I ve think about that the numbers are natural would help really much

zenith osprey
kind estuary
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To know the kind of form they have

zenith osprey
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Okay so

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2^6

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Amd 3^3

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Are satisfying

zenith osprey
kind estuary
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For witch number?

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Oh b and d

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Or?

lyric charm
#

btw whichwitch

kind estuary
midnight plankBOT
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leaden seal
midnight plankBOT
leaden seal
#

can someone check my answer please

zenith osprey
#

Are calculators allowed in exams tho?

leaden seal
#

yes

zenith osprey
#

alright

leaden seal
#

.close

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molten bay
#

24

midnight plankBOT
molten bay
shrewd tusk
zenith osprey
molten bay
#

Which rule?

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Nope

zenith osprey
#

+L hopital rule

molten bay
#

Any other idea?

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I know hospital rule

stiff panther
#

hello

shrewd tusk
molten bay
#

Could you explain it?

shrewd tusk
molten bay
#

But why?

shrewd tusk
#

so basically you get d(Upper limit)f(upperlimit)-d(Lowerlimit)f(lowerlimit)
so it becomes its ||2xsin((x^2)^2))-0||

zenith osprey
molten bay
zenith osprey
#

No

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Shi

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Mb

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It's 5

shrewd tusk
zenith osprey
#

Are you a jee aspirant?

echo topaz
zenith osprey
#

If so yea 12th ka part hai

echo topaz
#

🌞

zenith osprey
molten bay
#

Sunayo

zenith osprey
echo topaz
zenith osprey
#

Well Newton lebeniz theorem

molten bay
#

Question btao

echo topaz
#

is that 11th or 12 th grade

zenith osprey
#

Is in 12th usually integration ya differential equation mai padhate hain

shrewd tusk
zenith osprey
tough shale
zenith osprey
#

Nahi

tough shale
#

But it works

zenith osprey
#

Kaafi lamba hoga

zenith osprey
#

Agar nahi sikhaya toh

tough shale
#

Yeah, but that's the only alternate I can think of

tough shale
zenith osprey
tough shale
#

Oh, ok

thin tree
#

taylor*

zenith osprey
molten bay
#

Sab Indians at one channel🤣😅

zenith osprey
zenith osprey
molten bay
#

grade choro

shrewd tusk
#

or just take x^2 as t and integrate by parts if yk integration

zenith osprey
#

Are fir lebeniz theorem nahi aata kya?

molten bay
#

Integration k andar lagao kya maclaurie

zenith osprey
zenith osprey
#

Sinx^2 ko

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x^2/1!-x^6/3!+x^10/5!

molten bay
#

I got n=5

zenith osprey
#

Likhe ke integrate karo

molten bay
#

@zenith osprey

zenith osprey
#

Is hisab se

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Lemme check maine kya galti ki

zenith osprey
#

Toh x^6 hoga

molten bay
#

Yes

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(x^2)^3 hmm

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x^6/6x^n

zenith osprey
#

Yea

molten bay
#

Can I do all questions?

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Like this

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Where integration is included

tough shale
#

Honestly, depends

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Like, in the 26th question

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U can't get the series for (tan inv x)² easily

zenith osprey
zenith osprey
#

3 terms tak

tough shale
#

Par square hai

zenith osprey
#

Oh shit

molten bay
#

Lebiez wala send karna

zenith osprey
#

Han abhi dekha

molten bay
#

Which rule you applied?

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@zenith osprey

tough shale
zenith osprey
#

2nd wala

molten bay
zenith osprey
#

Sin(x^2) tha na

molten bay
#

No

zenith osprey
#

So limits dalne ke baad

molten bay
#

Next step

zenith osprey
#

Woh toh

molten bay
#

Around 0

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??

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So

zenith osprey
#

Sin(x)/x=1 se kiya hai

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Toh sin(x^4)/x^4=1

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And sin(x^4)=x^4

midnight plankBOT
#

@molten bay Has your question been resolved?

midnight plankBOT
#

@molten bay Has your question been resolved?

midnight plankBOT
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twilit field
#

I'm trying to parametrize this , would apprciate any inputs.
I start by re-writing $z=2-x^2-y^2$as $z=2-z^2$, whose soutions are $z=-2; z=1$.
\
As the cone opens upwards, $z=1$.
\
As is, the paraboloid is given by$(\sqrt{\cos^2(t)-2}, r \sin(t), 2-r^2); 0≤t≤2π; 0≤r≤1$

twilit field
grand pondBOT
#

What a wonderful world !

twilit field
#

oops

#

yea, I'm lost

#

so uh, let's start again

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x= rcos(t), y= rsin(t), z= 2-r^2

midnight plankBOT
#

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shrewd tusk
#

How do i find the height of centre of mass of a hemisphere?

shrewd tusk
#

like what do i integrate

cedar mason
#

do you know the centre of mass is.

shrewd tusk
#

yeah ik that i can do it for a semicricle

cedar mason
#

can you do it for a circle.

shrewd tusk
cedar mason
#

sure

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so

dusty portal
#

Would this not be using the centroid formula?

cedar mason
#

now you can compose a hemisphere out of a bunch of disks.

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which are just circles with some infinitesimal height.

shrewd tusk
#

ryt

cedar mason
#

can you proceed from here

#

it's literally just like how you would find the area of a hemisphere.

#

well, the integral setup, i mean.

shrewd tusk
#

I'm thinking give me a moment, ill ping if i need help

sharp coral
#

there is also a derivation using the pappus centroid theorem, if you've heard of that

shrewd tusk
sharp coral
#

so what class do you need this for? are you expected to derive the formula or just use it?

shrewd tusk
#

but i kinda keep forgetting

#

if i knew how to find it, it will stick in my head

sharp coral
#

i think that the pappus theorem would work for that

#

so we can imagine a sphere as a surface which is generated by revolving a semicircle around its axis

dreamy lichen
sharp coral
#

well by symmetry the centroid of a hemisphere should be the same, if we imagine it as being a semicircle pivoted about its center

sharp coral
#

well that's annoying

dreamy lichen
#

the mass thats further from the centroid gets more spread out sort of

shrewd tusk
#

its ||3r/8|| if you wer wondering

dreamy lichen
#

you'd need volume of a hypersphere to make the pappus theorem argument

#

maybe we could just do the integrating

shrewd tusk
#

like how does it vary

sharp coral
#

back to integration i think

#

if we look at it from the side the hemisphere looks like a semicircle

shrewd tusk
cedar mason
#

and radin stuff

#

so the radius is just $r \cos(\theta)$

grand pondBOT
shrewd tusk
cedar mason
#

not x or y

#

for example if this was the area of a hemisphere, we'd get the integral as $\int^{\frac{\pi}2}_{-\frac{\pi}2} \pi (r \cos(\theta))^2 r d\theta \sin(\theta)$.

#

I think.

#

Aaaand that's prolly spoiling it too much lol

#

,w \int^{\frac{\pi}2}_{-\frac{\pi}2} (r \cos(\theta) r \sin(\theta)) d\theta

#

nice

cedar mason
#

nvm

#

its right dw

shrewd tusk
#

i see give some time to process it lol

cedar mason
#

whoops i forgot what area even is

shrewd tusk
#

isnt it like pi r^2 h

#

ah yeah

#

that makes sense

grand pondBOT
shrewd tusk
#

i think u put pi in bracket bymistake?

cedar mason
#

IM NOT SURE THIS IS RIGHT

#

NVM IGNORE ME

shrewd tusk
cedar mason
#

yeah i was doing a up and down thing

#

idk whats going on

#

but the general idea is fine 😭

shrewd tusk
#

i think its 0

#

for hemisphere

cedar mason
#

the correct integral is $4\int_{0}^{\frac{\pi}{2}}\pi r^{2}\cos^{2}\left(x\right)r\sin\left(x\right)dx$

grand pondBOT
cedar mason
#

but not sure why

cedar mason
shrewd tusk
#

ah ok

cedar mason
#

AH

#

LMAO

#

alright i just brain fogged the wrong trig function

woeful turret
#

no it is not 0

cedar mason
#

it's $\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}\pi r^{2}\cos^{2}\left(x\right)r\cos\left(x\right)dx$

grand pondBOT
cedar mason
woeful turret
cedar mason
shrewd tusk
#

I see so its correct

woeful turret
shrewd tusk
woeful turret
#

so ur preparing for jee?

last slate
#

today

shrewd tusk
last slate
#

oooh

woeful turret
last slate
#

idk if ill qualify for that

#

im on the brink

woeful turret
last slate
#

only math and physics carrying me

last slate
#

chem i fked up

shrewd tusk
woeful turret
shrewd tusk
#

the integration stuff helps

#

in other problems

woeful turret
last slate
shrewd tusk
woeful turret
woeful turret
#

all 3?

woeful turret
last slate
#

all of chem

woeful turret
#

oh but why

last slate
#

i did not study for it

#

i hate chem

shrewd tusk
last slate
#

its just memorising and shit

#

and there are hell lot of exceptions

woeful turret
#

oh

#

yeah fr

woeful turret
last slate
#

yup yup

last slate
shrewd tusk
#

well ill get around 170-180 ish

last slate
#

Damn

woeful turret
last slate
#

ill get around 100

last slate
shrewd tusk
#

i only did 50 Qs

woeful turret
#

oh no ;/

last slate
#

i did 49

#

bye anyways

shrewd tusk
#

byee

woeful turret
#

99%ile higher u should get

thorny plinth
last slate
#

i find advance easier than mains😭

woeful turret
#

.

last slate
woeful turret
#

naw

last slate
#

yup

shrewd tusk
thorny plinth
shrewd tusk
#

mains is more memory based which sucks

last slate
last slate
thorny plinth
#

i love worms

last slate
thorny plinth
#

i feel the same

shrewd tusk
woeful turret
woeful turret
shrewd tusk
thorny plinth
shrewd tusk
#

like split into discs

last slate
last slate
shrewd tusk
#

and assume rcostheta and rsintheta smtn smtn

woeful turret
shrewd tusk
thorny plinth
#

(experience)

shrewd tusk
#

maths was like mains

woeful turret
#

ohh

thorny plinth
#

||i got 243 in mains and dint even get 99.9||

woeful turret
#

not possible

#

no shift cutoff was that high

thorny plinth
#

29jan s2 2024

woeful turret
#

except that one

#

people were saying that paper got leaked

last slate
shrewd tusk
thorny plinth
shrewd tusk
thorny plinth
thorny plinth
#

also 27th was like that

woeful turret
#

@thorny plinth any tips for me 🙏

thorny plinth
#

uh sure dms ig we should stop flooding the channel

last slate
#

yup

woeful turret
#

yeah okay xd

shrewd tusk
#

yeah ill close ig

#

.close

midnight plankBOT
#
Channel closed

Closed by @shrewd tusk

Use .reopen if this was a mistake.

slow thorn
#

it just sticks after a while

#

after you see some problems

shrewd tusk
# slow thorn 3R/8

well i dont have time to practice a ton of problems on one formula, so its faster to just learn the derivation, and as a bonus ill also learn a new method

slow thorn
#

if you really want integration

#

1 min

shrewd tusk
#

.reopen

midnight plankBOT
#

slow thorn
#

filled is again another layer of integrating with hollow hemispheres

#

so it's quite a lengthy proof

cedar mason
#

almostttt there

#

the height isnt actually r d theta

#

thats the slant

#

wait

#

youre not op

#

freaking

#

!nosols

midnight plankBOT
#

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.

slow thorn
#

yes

#

what

#

he asked for another method

cedar mason
#

also its wrong

cedar mason
#

okay

#

but its still wrong tho

slow thorn
#

why so

#

isn't it R/2?

cedar mason
slow thorn
#

i never said the height was R d theta?

#

that's the thickness of the strip

shrewd tusk
cedar mason
slow thorn
#

im so sorry

#

past me handwriting was horrible

#

that's a sigma

shrewd tusk
#

oh

slow thorn
#

areal density

shrewd tusk
cedar mason
#

you still got the thing super wrong right

slow thorn
#

looks safe

cedar mason
#

you need that trig factor there

slow thorn
#

answer also matches

#

meaning?

cedar mason
shrewd tusk
slow thorn
cedar mason
#

AH

#

okay

shrewd tusk
#

then using that hes finding for solid

cedar mason
#

apologies

slow thorn
#

solid is a bit more arduous than this

shrewd tusk
#

hmm well yeah i think Percy's disk method is better if we just want the solid (although im still figuring it out)

slow thorn
#

maybe

shrewd tusk
#

thanks for your help!

#

.close

midnight plankBOT
#
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midnight plankBOT
#
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molten bay
midnight plankBOT
molten bay
#

I didn't understand the question properly and option and the =p part?

molten bay
#

If I check the condition random values like i out integer x=2

#

2-2=0

#

[2+h]+[2-h]

2-3=-1

#

Not continuous at integers

#

Now let me check at non Integers

#

like 2.5

#

At x=2.5

shrewd tusk
shrewd tusk
molten bay
#

2-3=-1

#

2.5+h it will be same

#

And at x=2.5-h same

#

So non integers yooo

#

B and D

#

Am I right?@shrewd tusk

#

@cedar mason

cedar mason
#

i dont really understnand man sorry

shrewd tusk
#

one sec let me check

#

yeah your ryt @molten bay

#

the funcn is 0 whenever its an integer

#

and -1 otherwise

molten bay
#

Thanks

molten bay
#

@shrewd tusk

shrewd tusk
#

for continuity you should be able to draw the graph without lifting your pen up

#

clearly you cant do that at the integers

molten bay
#

Thanks

#

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wet cairn
#

How would I find the perimeter of thisss??

midnight plankBOT
wet cairn
#

Would the red dotted lines be 10cm each?

cerulean solar
#

Not necessarily, but using the pythagorean formula we can confirm that it is the case in this question

#

I’m assuming those are semi-circles

wet cairn
#

ohh how'd u use the pythagores therom?

#

oh like a squared plus a squared

cerulean solar
#

a^2+b^2 = c^2

wet cairn
#

is 14.14 squared?

#

a2+a2=14.14 squared???

#

is that how u got it?

#

IM LIKE 13 DUDE 🙏

cerulean solar
#

Actually the other side length technically isn’t 10, I was too hasty and rounded up by accident

wet cairn
#

aren't the two red dotted lineds equal?

cerulean solar
#

No, they are different by just the tiniest fraction

wet cairn
#

💀

#

this a year 9 problem

#

surely

#

like

#

there is some leisure

#

and we're supposed to asumme

fathom atlas
wet cairn
#

they're equal rightt?

cerulean solar
#

The other side is about 9.996979

wet cairn
#

ohh okk

cerulean solar
wet cairn
#

fair enough

#

9.99??

#

duh

#

anyways

#

so if the red dotted lines are 10 each

#

then

#

the perimeter would be 20+14.14??

#

for the traingle at least

cerulean solar
#

The dotted lines are not part of the perimeter

wet cairn
#

rllyy??

#

oh

#

im so sorry

#

ur right that makes sense

cerulean solar
#

You now need to find the perimeters of the semi-circles

wet cairn
#

ok

#

yeh

#

so

#

the perimeter of the semicircle

cerulean solar
#

The formula for the circumference of a circle is 2(pi)(radius)

wet cairn
#

since they are equal i can just double my answer right?

#

so

#

pi times diamter here is

#

10 pi

#

31.4159265359

#

as accurate as it gets

#

and then double that?

cerulean solar
#

Yes

wet cairn
#

62.8318530718

#

but then

#

we gotta half right?

#

since its a semicircle

#

so go back

#

to 31.4159265359

#

correct?

cerulean solar
#

However, technically one of the sides isn’t a diameter of 10,

cerulean solar
wet cairn
#

for the perimeter of BOTH semicircles?

wet cairn
#

cool

#

so

cerulean solar
wet cairn
#

31.4159265359 added to 14.14

#

is the perimeter of the entire composite shape?

#

45.5559265359

#

which

#

rounded to 2

#

is 45.56

#

yess thank u

#

wbt area?

#

rq

#

how would i find the area of the triangle?

wet cairn
cerulean solar
wet cairn
#

aight aight

#

is the area of the triangle

#

50cm sqaured??

#

10 times 10 divided by 2

#

i got it thnks (;

#

.closed

#

.close

midnight plankBOT
#
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midnight plankBOT
#
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hazy seal
#

isnt the answer 130 because inscribed angles are half of the arc?

lyric charm
#

mm careful though

#

there is an arc here that measures 130° but it isn't MW

hazy seal
#

🤔

lyric charm
#

look carefully at what arc the 65° angle (AHW) actually subtends

hazy seal
#

AW?

lyric charm
#

i would call it AMW just to be safe

#

but yes

#

so that arc measures 130°

hazy seal
#

yes and then you take away 60

lyric charm
#

exactly

hazy seal
lyric charm
#

was that a strict rule in your class?

hazy seal
lyric charm
#

cause in my experience naming an arc by 3 letters is just a more general disambiguation for when there's any uncertainty which way to go

#

2 letters is fine for arcs that are visually small

#

with no hard boundary for where such usage is acceptable

hazy seal
#

.close

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rigid turret
rigid turret
#

Screenshot if u prefer

small jasper
#

Idk why this is 2/3

#

it should be 4/3

#

If it's 4/3, then you also get 1/16

midnight plankBOT
#

@rigid turret Has your question been resolved?

rigid turret
#

@small jasper is 3/2 = 4/b false

small jasper
#

But you want h in terms of b in general

#

so

rigid turret
#

yea

#

yep im good

small jasper
rigid turret
#

db/dt = 4/3 dh/dt

midnight plankBOT
#
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rigid turret
#

both my method were good

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lavish venture
#

Show that the map

[d_A \colon X \to \mathbb{R}^{\geq 0}, \quad d_A(x) = \inf{d(a, x) \colon a \in A}]

is continuous

grand pondBOT
lavish venture
#

so i've taken an open set $U \subset \mathbb{R}^{\geq 0}$ and then let $x \in d_A^{-1}(U)$ or equivalently, $d_A(x) \in U$ and then since $U$ is open i know there exists $\varepsilon > 0$ so that the ball of radius epsilon (open interval) is contained in $U$

grand pondBOT
lavish venture
#

but i am struggling to see how i can extract a delta from this to show there is a ball of radius delta for some delta that is contained in the inverse image of U

#

like if i have some epsilon neighborhood around d_A(x) contained in U then this epsilon certainly has to be important

#

is it true that the distances between my points in the space X will also be less than epsilon if their corresponding distances to A are less than epsilon?

#

it has to be related somehow

#

surely

#

ping me if you have an idea

midnight plankBOT
#

@lavish venture Has your question been resolved?

lavish venture
#

.close

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slender lagoon
midnight plankBOT
slender lagoon
#

Just straight up idk what to do here

midnight plankBOT
#

@slender lagoon Has your question been resolved?

slender lagoon
#

No

gaunt plume
#

See if you can work out what $\cos\theta$ is

grand pondBOT
#

depression

midnight plankBOT
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manic bison
#

in such an expression is TV a constant

(C is a constant here)

polar star
#

T and V can vary such that they output the same value C

lyric charm
#

zero context...

manic bison
manic bison
#

sorry if im being dumb

polar star
#

do you mean VT^(C_v/R)

manic bison
#

yes

polar star
#

and you are keeping C constant?

manic bison
#

yes

polar star
#

like we saw in the log form, there exists some T and V such that VT^(C_v/R) = C where C is constant but T≠V

#

u can visualize a range of values by looking at VT^(C_v/R) = 5 for example

polar star
#

with defined heat capacity and 8.31

#

,w plot x*y^(4/8.31) = 5

grand pondBOT
manic bison
#

so if sum of logs is constant their arguments rpoudct is also constant?

manic bison
polar star
#

what exactly are you asking

polar star
#

from those variables

polar star
#

are you asking if log(x)+log(y) is constant then xy is constant?

manic bison
#

yes

#

oh wait

#

you conbine log

#

sorry

#

i was being dumb

#

.close

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#
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twilit field
#

Consider the seqeunce given by $b_n=.n -\sqrt{n^2+2n}$ Taking $(1/n} \to 0$ as given , and using both the algebric limit theorm and the fact that if $x_n \to 0$, then $\sqrt{x_n} \to 0$. Show lim $(b_n)$ exists and find the limit

grand pondBOT
#

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

twilit field
#

so to start , I re-write this as $b_n= \frac{ -2n}{ n+ \sqrt{n^2+2n}}$
\
$\frac{-2n}{ n( 1+ \sqrt{1+ \frac{2}{n}}$
\
dividing the numerator and denominator by $n$
\
$\frac{-2}{ \sqrt{ 1+ \frac{ 1 + \frac{2}}{n}}$
\
as $\frac{1}{n}$ goes to 0 and $1+ \frac{2}{n} \to 0$
\
$\sqrt{ 1+ \frac{2}{n}}\to 0$
\
We then have $1 + \sqrt{ 1+ \frac{2}{n}} \to 2$
\
We then have by quotient rule, the limit is $-1$

grand pondBOT
#

What a wonderful world !

so to start , I re-write this as $b_n= \frac{ -2n}{ n+ \sqrt{n^2+2n}}$
\\
$\frac{-2n}{ n( 1+ \sqrt{1+ \frac{2}{n}}$
\\
dividing the numerator and denominator by $n$
\\
$\frac{-2}{ \sqrt{ 1+ \frac{ 1 + \frac{2}}{n}}$
\\
as $\frac{1}{n}$ goes to 0 and $1+ \frac{2}{n} \to 0$
\\
$\sqrt{ 1+ \frac{2}{n}}\to 0$
\\
We then have $1 + \sqrt{ 1+ \frac{2}{n}} \to 2$
\\
We then have by quotient rule, the limit is $-1$
```Compilation error:```! File ended while scanning use of \frac .
<inserted text> 
                \par 
<*> 796939110815629322.tex
                          
I suspect you have forgotten a `}', causing me
to read past where you wanted me to stop.
I'll try to recover; but if the error is serious,
you'd better type `E' or `X' now and fix your file.```
normal prawn
#

do we need to find the limit of n-√(n²-2n) when n approaches infinity?

twilit field
#

yes

#

it's -1

#

I know that

normal prawn
#

Limit is -1?

#

how

twilit field
#

isn't it

normal prawn
#

idk I'm not good when it comes to limits lol

twilit field
#

,w lim n -sqrt{n^2+2n}

#

okay, 1

#

my bad

twilit field
#

wait

#

no

normal prawn
#

1 how?

#

0?

twilit field
#

it's -1

normal prawn
#

Howw

twilit field
normal prawn
#

howow

twilit field
#

this should explain it , if I can render it

#

so to start , I re-write this as $b_n= \frac{ -2n}{ n+ \sqrt{n^2+2n}}$
\
$\frac{-2n}{ n( 1 + \sqrt{1+ \frac{1}{n}}}$
\
dividing the numerator and denominator by $n$
\
$\frac{-2}{\sqrt{1+ \frac{1}{n}}}$
\
as $\frac{1}{n}$ goes to 0 and $1+ \frac{2}{n} \to 0$
\
$\sqrt{ 1+ \frac{2}{n}}\to 0$
\
We then have $1 + \sqrt{ 1+ \frac{2}{n}} \to 2$
\
We then have by quotient rule, the limit is $-1$

grand pondBOT
#

What a wonderful world !

twilit field
#

finally

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.close

midnight plankBOT
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twilit field
#

Prove that there's no such seqeunce or give a counter example
\
An unbounded seqeunce (a_n) and a convergent seqeunce (b_n) with (a_n-b_n) bounded

placid spoke
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what have you tried

twilit field
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I was thinking that such a seqeunce would exits

placid spoke
#

do you have any reason why you think that

twilit field
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idk, just a feeling

placid spoke
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well what do you know about convergent sequences

#

can those be unbounded

twilit field
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A convergent seqeunce is always bounded

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right

placid spoke
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yes

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so an unbounded sequence minus something bounded

twilit field
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An unbounded seqeunce - a convegrent sequence is always not convergent

#

same proof as previosu problem

placid spoke
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well an unbounded sequence - a bounded sequence cannot be bounded

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it's like infinity - some number

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and if a sequence isn't bounded, you know it can't converge

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so it's very similar to the previous one yeah

grim vector
#

the question is wierd

west sapphire
#

Hello can I submit a theroy of mine?

grim vector
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if you have a_n - b_n bounded

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and b_n convergent (so bounded)

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a_n should be bounded

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(sum of bounded sequences is bounded sequence)

west sapphire
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It's possible how we got four dimensions or more and time

grim vector
midnight plankBOT
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@twilit field Has your question been resolved?

night axle
#

Which is ultimately the same but a different way of seeing the same thing

grim vector
#

sure sir

molten bay
twilit field
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.close

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violet dune
#

would i use integration by parts for this? $\int(2^{x+1}*3^{x+4})dx$

grand pondBOT
runic hamlet
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combine them into a single exponential

violet dune
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how do i do that if they dont have the same base or exponent?

fallow scarab
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$a^b = e^{b \log(a)}$

grand pondBOT
#

riemann

violet dune
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what if i make it $2^x23^x*3^4$?

grand pondBOT
violet dune
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then would it be $162\int(2^x3^x)dx$?

grand pondBOT
fallow scarab
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hmmcat that's a good step yes

violet dune
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and does the inside simplify to 6^x or does it not work like that?

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because then integral of a^x = a^x/lna right?