#help-27

1 messages · Page 290 of 1

potent onyx
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N/2{ 4 + (N-1)D]

sullen island
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yeah yeah got it

potent onyx
#

ok

sullen island
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what about the bottom AP then

potent onyx
#

bottom AP?

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what is that

sullen island
#

7+11+...

potent onyx
#

oh

grand portal
#

Are your exam questions multiple choice ?

potent onyx
#

only 20 question are MCQs

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each of 1 mark

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@sullen island

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what if we use N/2(a+l)

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?

sullen island
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what's l here

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I don't care as long as the formula computes what you actually wanna compute yk

potent onyx
#

l is last term

sullen island
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yeah so it's essentially the same thing, it doesn't matter which one you pick

potent onyx
#

oh wait

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l is 23?

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right

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so N/2( 2+ 23)

sullen island
#

no

potent onyx
#

then what is 23

sullen island
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you have n terms

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l = 2 + 3(n-1) then

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so really it doesn't matter what formula you pick

potent onyx
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if we continue the AP

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23 = 8th term of this AP

sullen island
#

ok why are you taking the 8th term tho

potent onyx
#

a+7d = 23

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2+ 7(3)

sullen island
#

and why would you want that to be 23

potent onyx
#

I am not trying to make that 23

sullen island
#

why is it

potent onyx
#

it is 23

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cus a = 2 and d = 3

sullen island
#

that still doesn't tell why you're taking the 8th term of the AP tho

#

you're going in circles

potent onyx
#

no

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see

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how we will find 8th term of AP?

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the formula is

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a + 7d

sullen island
#

how does that help you solve your question ?

potent onyx
#

idk

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I am trying random things to find the solution

sullen island
#

well I was guiding you towards a way until you started talking about the 8th term

potent onyx
#

ok

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sry

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u can contiune

sullen island
#

we're just trying to find a nice expression for the numerator and the denominator

potent onyx
#

yes

sullen island
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and then you'll get an easy equation to solve for n

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ok so the numerator is this

potent onyx
#

yes

sullen island
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what about the denominator then

potent onyx
#

btw i think we have to divide this whole AP

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by the bottom AP

sullen island
#

yes

potent onyx
#

like 2/7

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5/11

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I am not sure

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cus this question should be easy which we can solve under 2 mins

potent onyx
sullen island
#

it's certainly doable in 2 mins, you're going all over the place tho

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same as before you got that 2 + 5 + 8 + ... [n terms] = n/2 (1 + 3n)
what about 7 + 11 + ... [n terms] ? you can just use the same technique, no need to wonder about the meaning of life or whatever

potent onyx
#

btw can u tell me what is 23 in this question

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and 35

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it is Sn ?

sullen island
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no

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it doesn't have to be at least

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here it's certainly not if we're looking at the choices

potent onyx
#

lets use the value of the options

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first 17

sullen island
#

sure if you want

devout snowBOT
#

@potent onyx Has your question been resolved?

crisp tapir
#

is it in division?

potent onyx
#

idk man

potent onyx
devout snowBOT
#

@potent onyx Has your question been resolved?

#
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pure flower
#

I could if I could read that

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oh beautiful timing lol

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okay

potent onyx
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late

pure flower
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nice if you got it

potent onyx
#

not resolved but still closed

pure flower
#

i'd recommend getting a new book btw /lh

devout snowBOT
#
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floral ridge
#

If f and g are functions from R to R then does f(x)g(x)=0 for all x in R imply f(x)=0 or g(x)=0 for all x in R?

tall stirrup
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Multiplication of two non-zero real numbers is a non-zero real number, so yes

floral ridge
#

I can prove this if f and g are polynomials

floral ridge
stone stump
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yes

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you want to conclude that f is zero everywhere or g is zero everywhere?

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thats just false

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you need stronger conditions for your functions

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much stronger

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not even sure what conditions would be enough for that

floral ridge
stone stump
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I suppose you can just say g is non constant and f is continuous

floral ridge
#

Maybe

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What made me question this stuff is that on the curve x^2-y^2-1=0, the product of (y+sqrt(x^2-1))(y-sqrt(x^2-1))=0 (yes I know that I went to two variables but i wanted to give an example)

floral ridge
#

Oh wait that's obvious I can take f=0 for all x≠0 and f(0)=1 and g be any function with g(0)=0

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So maybe f and g to be continuous ig

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I guess I answered my own question but I wanna extend it

iron sun
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You can create crosstalk, and let one of them be zero for enough x’s so that the other continuously becomes non zero

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And so on

devout snowBOT
#

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sturdy mango
#

how do i find its congruence modulo with 9

sturdy mango
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i tried smth with 8 but failed

fossil locust
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try finding 2^(2024) mod 9 first

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think of what happens with 2^3

sturdy mango
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2^3 = -1 mod 9

fossil locust
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yeah

sturdy mango
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i thought that 2^6=-1mod 9 and 2^2024 is def even so i can multiply an evne number in power so ans should be 1

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but it is apparently wrong

alpine python
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2^6 is 1 mod 9

fossil locust
sturdy mango
fossil locust
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yeah you need to apply the idea of powers of 2^3 ofc

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there will be some remainder with 3 and 2024

sturdy mango
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if every power of 2 is even

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then 2^6 = 1 mod 9

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why cant i raise both side to said even number

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and say 1 is ans

fossil locust
sturdy mango
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any

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why would it matter since 1 ^anything is 1

fossil locust
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is 2024 a multiple of 6

sturdy mango
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ohhhh

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nah it isnt not div by 3

fossil locust
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yeah exactly

sturdy mango
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4

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ans is 4

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i broke 2024 in 2022 and 2

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2022/3=674 so i can make it 1 and multiply 4=-5mod 9

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2^2024=-5mod9

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2^2024=4mod9

fossil locust
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absolutely, that's correct

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I think you can figure out what to do now for 2^(2^(2024))

sturdy mango
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not sure still

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it has it in power?

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i could multiply if it was just in base

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or is there any rule here i am not aware i think i am getting the ans

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but not sure why this is valid

fossil locust
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you can replace 2^2024 with 4 directly

sturdy mango
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ohh

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so when can i do that

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i k that for multiply u multiply both side if same modulo

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or add

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and raise power

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not sure about others

fossil locust
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might help to know why say (9p + q)(9r + s) leaves the same remainder as rs mod 9

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so that is multiplication sorted, and exponentiation is just repeated multiplication

sturdy mango
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yeah

fossil locust
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yeah turns out it works for pretty much any operation

sturdy mango
#

is there any resource i can see for this matter?

fossil locust
#

square roots you have to be careful

sturdy mango
#

like handy rules or formulas so to speak

fossil locust
#

so like a square root, that has a positive and negative value for modular arithmetic

sturdy mango
#

hh

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ohh

fossil locust
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maybe this might help

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basically more worked examples, I'm struggling to think of a textbook which has this exactly

sturdy mango
#

okkkk

fossil locust
#

maybe AoPS Introduction to Number Theory

fossil locust
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devout snowBOT
sturdy mango
#

they didnt touch this

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about replacing the power

fossil locust
#

it's a bit inevitable but this principle of substitution is super important

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I'm surprised too

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I guess worked examples help a lot

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and your own practice, for this purpose

sturdy mango
#

yeah i cant find anything

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on the internet worth reading on this about finding remainder problems

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#

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native stone
#

i want someone to teach me how to solve this using sec x

native stone
#

but have patience with me since i very rarely used it

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also i want to know when are trig substitutions useful, are they useful whenver theres a sqrt

final drift
#

um there is no hard rule

native stone
#

or are they useful whenever you got an x^2+1 or 1-x^2?

final drift
#

there is not any "formula" of when and what you have to do u-sub, you always have to guess

echo gate
#

generally yeah

native stone
native stone
echo gate
final drift
#

yeah this is true

native stone
#

wow

echo gate
#

honestly memories something like this

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It's a bit of a pain but you get used to them after a while

native stone
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i cant believe you gave me this cheat sheet

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this is amazing

echo gate
#

hope it helps

native stone
#

it doesss

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ok so in the case of the exercise that i sent

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first thing we substitute x=tgx

echo gate
#

Do you mean tan there

native stone
#

yea yea

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tg = tan

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same thing

echo gate
#

my bad

native stone
#

no prob

echo gate
#

yeah thats right

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and if you know your trig rules the problem solves quite nicely

native stone
#

let me try

echo gate
#

good luck

native stone
#

i will send you as i try to solve it because idk if i can do it

echo gate
#

No worries Im happy to help

native stone
#

yay

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ok so i fucked up

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but ill send you what i got

echo gate
#

let's see it

native stone
#

here

echo gate
#

the derivative of tan(x) is sec^2(x)

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also

native stone
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goddamnit

echo gate
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tan^2+1 = sec^2

native stone
echo gate
#

this should clean it up very nicely

native stone
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ok so

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i wouldve gotten int of sqrt sec x d(tgx) instead

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after i modified

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so what do i doe after that

echo gate
#

sorry can you send me a photo

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I don't really follow your notation

native stone
#

here

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i modified

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d(tanx)

echo gate
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tan^2(x)+1=sec^2(x)

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you did tan^2(x)+1+sec(x)

native stone
#

oh

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yea i told you im not used to sec

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so im doing stupid mistakes

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at first

echo gate
#

fair enough

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takes a while but sec is super useful in integrtion

native stone
#

okk, i hope i did do someting stupid this time too

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here you go

echo gate
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thats correct

native stone
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so if that is right, the following question is

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how do i solve that?

echo gate
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you have to substitute the original x

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after integrating

native stone
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how do i integrate that?

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is it just sinx?

echo gate
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yeah

native stone
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why?

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we got d(tanx)

echo gate
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you've already done d(tan(x))

native stone
#

shouldnt we substitute with t or somehting?

echo gate
#

its sec^2(x)

native stone
#

its like

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we are integrating in terms of tgx not in terms of x

echo gate
native stone
#

right?

native stone
echo gate
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i don't really understand the integrate in terms of tgx

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I would substitute it at the start

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I thought you did that and you were using a different x

native stone
#

no

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its the same x

echo gate
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oh

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in that case

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you cannot do x=tanx

native stone
#

i cant?

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oh well actually

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that makes sense

echo gate
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if you do like x=tant

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everything is the same

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and you end up with sint

native stone
#

ok sure lets say that the integral was cost dt

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is that how u got it?

echo gate
#

yeah

native stone
#

or how does it look for you

echo gate
#

i can send my solution as well if that helps

native stone
#

no wait this isnt making any sense for me

native stone
echo gate
#

give me a second

native stone
#

ok

echo gate
#

I don't want to spoil the rest cause it's pretty interesting

native stone
#

aha ok

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so i just got lost because of that confusing notation i did

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i see

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yours is way cleaner

echo gate
#

does that make sense

native stone
#

ok so now you got sin t as the result

native stone
#

no it does

echo gate
#

brilliant

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can you solve it from there

native stone
#

nope

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we would get

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sin arctan x

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which idk the formula to

echo gate
#

try to work it out using a triangle

native stone
#

god do i gate those formulas

fossil locust
#

let theta = arctan x

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so you know tan theta

native stone
#

yes go onnn

fossil locust
#

like let adj = 1

native stone
#

yup

fossil locust
#

opp = theta

native stone
#

huh?

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opp and adj?

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whats that?

fossil locust
#

you just need to find hyp

native stone
#

hyp?

fossil locust
native stone
#

oh

fossil locust
#

draw a right triangle as was mentioned

native stone
#

ok im gonna draw i

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it

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so theta is an angle

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right?

echo gate
#

yeah

native stone
#

oh it needs to be a right triangle

echo gate
#

Doesn't need to be but it's way easier if you do it like that

native stone
#

aha ok

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so then what do you do?

echo gate
#

What do you think the sides are

native stone
#

ill draw it and show u

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oh

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yea so the side facing theta

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should be x

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and the one below theta

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shoul be 1

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maybe?

echo gate
#

That's right

native stone
#

oki

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good

echo gate
#

Then you can find the long side with Pythagorean theorem

native stone
#

OMG THATS AMAZING

#

IM LEARNING SO MUCH

echo gate
#

STUPENDOUS

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then once you put sin you're all done

native stone
#

and i can do this for acrsin, arccos and arcctg as well?

fossil locust
#

same trick for all of those

native stone
#

thats absolutely insane

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i cant believe it

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so i dont have to memorize a billion formulas

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wow

echo gate
#

Super useful to know

native stone
#

math is amazing

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ok so

native stone
echo gate
#

yeah

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I can find the one I used

native stone
#

send me

echo gate
#

it also has some hyperbolic substitution

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but Im pretty sure its the same

opal flume
#

i do not like math

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wich is why im here

echo gate
#

super similar

echo gate
native stone
#

its gonna get easier

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and more fun

native stone
#

i cant believe my eyes

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wait

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whats a cosh u?

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is that hyperbolic stuff?

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bc it seems highly advanced

opal flume
#

x6 - 132x5 +7260x4 - 212960x3 + 3513840x2 - 30921792x + 113379904 = 0
ts can not get easier😭

echo gate
echo gate
#

the integration you're doing i tougher

native stone
#

i love your confidence

echo gate
#

sinh and cosh are just the same as sin and cos

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they aren't the same but super similar

native stone
#

i need a masterclass on these kind of substitutions

opal flume
native stone
#

thats literally the most important thing when it comes to integration

echo gate
#

I can send you the integration document

native stone
echo gate
#

Are you in school or in uni

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if you're in school this stuff is a bit advanced

native stone
#

these things that im doing are solely for uni

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so idk if that means something

echo gate
#

good enough for me

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so basically this is like a document which has all the basic inegration techniques

native stone
#

this book i got has only hardcore uni exam exercises

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that are really easy for a math lord like u

echo gate
#

all the good substitutions etc..

echo gate
#

its what i'm going through right now

native stone
#

i nib

#

i nib integration doc

echo gate
#

I'm only good at integration cause i've been going through the doc like mad the past few days

echo gate
#

It's prep for the uk integration bee

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also

native stone
#

it only has 31 pages

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whaaaaaaaaaaaaaat

echo gate
#

this is the main page so you can find more problems and stuff

native stone
#

thats hilarious

echo gate
#

its good fun

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if youre studying in the uk hopefully ill see you there

native stone
#

i may study in the uk at some point

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because we got exchange programs

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but idk

echo gate
#

Theres integration bees everywhere

fossil locust
#

MIT's is the most famous

echo gate
#

you're really good for still in school so you should bee sorted

native stone
#

ok so you got all of those screenshot and everything

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from that doc

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that u sent me?

native stone
echo gate
#

no screenshots are from some other resources

native stone
#

lmao

echo gate
#

I was not doing that in school dawg

native stone
#

i nib

echo gate
#

I honestly have no idea where i got the screenshots

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I suspect it's from the A-levels further maths textbook

native stone
#

that doesnt mean much

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we do just a few more things than other countries dont do

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but ye

native stone
#

hmm

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ive heard of that

echo gate
#

thats the uk system

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not what I did but im studying there now so I've been having look

native stone
#

thats the german system too

echo gate
#

they making yall work hard

native stone
#

but see

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they make us learn all these formulas

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without knowing how to prove them

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which is really stupid

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because it focuses more on memorisation than on logic

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but yea

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ill keep this chat open to note down every single importnat piece of imformation that you gave me

#

thanks a lot

echo gate
#

No worries

#

become the integration beast i know you can be

native stone
devout snowBOT
#

@native stone Has your question been resolved?

native stone
#

.close

devout snowBOT
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spring oasis
devout snowBOT
spring oasis
#

triangle AXY is isósceles

sage burrow
#
  • you have 3 isiceles triangles. therefore 2 angles in such a triangle are the same
  • the sum of angles in a triangle is 180
  • angles which give a line sum up to 180.
  • one angle is given.

thats all you need.

spring oasis
#

I need more hints

sage burrow
#

use the given hints.
if you stuck, show where you stuck.

spring oasis
#

we need to find a

sage burrow
#

you know something about d and you know something about b, which you didnt use yet.

spring oasis
#

b+d=120

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b = 120-d

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d = 120-b

sage burrow
#

the angle sum in BCY is?

spring oasis
#

120 - d + 2c = 180

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2c-d=60

sage burrow
#

what is a+c?

spring oasis
#

unsure

sage burrow
#

can you find a (single) triangle where one angle is a and another is c?

spring oasis
#

I dont know what to say

sage burrow
#

you have at the end 6 triangles in your sketch, right?

spring oasis
#

3 triangles

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wdym 6

sage burrow
#

6 was wrong, but there are more than 3. AXY, XYB, YBC, AYB, ABC

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look at this triangles. is there one of them with one angle a and one angle c?

spring oasis
#

I pressume not? where are you going w this

sage burrow
#

what are the angles in ABC?

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you should not presume. you should check.

spring oasis
#

a, 120, c

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a + 120 + c = 180

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a + c = 60

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a = 60 - c

sage burrow
#

well. now look at your sketch, you have one angle named 180-a-c, right?

spring oasis
#

180 - 60

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= 120

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xyb = 120

sage burrow
#

so b is?

spring oasis
#

b = 30

sage burrow
#

so a is?

spring oasis
#

2a + 180-30 = 180

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2a = 180-(180-30)

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2a = 30

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a = 15

sage burrow
#

any questions left?

spring oasis
#

I appreciate the help

#

this was a tough one, tbh

#

at least for me, I was blocked I couldn't see it

#

.solved

devout snowBOT
#
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devout snowBOT
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summer igloo
#

hm

devout snowBOT
summer igloo
#

Hopefully I can keep my composure this time.

#
  1. Please describe the base-concepts/inner workings of polynomials.

  2. If I understand correctly, a polynomial is a set of operations as well as X values which you would like to solve the "X" value for. We assume/set the result of the list of operations values to zero and then find a value where this will be true.

Q@A

  1. Can you further describe what I mentioned in 2. and what the polynomial represents and what the roots represent? Is it just for describing the behavior of the set of operations?

  2. Im confused because they had the number 11 after various substitutions like adding 9 to make a completed square but then they undid this and isolated a singular binomial to solve for X.

  • If I am correct this works because the real goal of a polynomial is just to solve for X given the polynomial is equal to zero.
dense jay
#

thats not the 'goal' of a polynomial, a polynomial on its own is just a structure
you in the picture above youre solving for when the polynomial on the left is equal to 11

so the root here is the point where y=x^2+6x+9 and y=11 intersect

im unsure what you mean with the rest of it though
they didnt undo anything

summer igloo
#

They also deleted -2 and added +2 to resolve this.

dense jay
#

alright so it was x^2+6x-2=0?

summer igloo
#

he then deleted -2 by doing =2 at the end

dense jay
#

theyre essentially just deriving the quadratic formula if you want to see it that way

summer igloo
#

and then he did 6div2 = 3^2 into the 9 you see

dense jay
#

alrighty, but they didnt undo anything, they just factorised the square, then solved

summer igloo
# dense jay alrighty, but they didnt undo anything, they just factorised the square, then so...

alr so they substituted by forging 9 and deleting -2 which resulted in 11 from the substitution operations to make a complete square.

What confuses me is how they can do all of that without breaking equality which my best guess for why this is possible is that because of the way eleven is there throughout the whole thing it somehow keeps the quality

something I also was confused at first by was how they took (x+3)^2 and rooted it because it was already seemingly complete and if each binomial multiplied would be the value of X then how would that be right?

if i am correct is this because they are ONLY trying to solve for X so even if they break it into one binomial this could be considered easier as it allows you to solve by breaking the 11 down and subtracting 3 eliminating all operations affecting X?

dense jay
#

equalities will be maintained so long as you do the same thing on both sides, they added a 2 and then a 9 to both sides so theres no issue there

in the same way x=x
x+2=x+2 x+2+9=x+2+9, things are maintained

it was a complete square so by square rooting both sides we can then work with an equation where solving for just 'x' is relatively straight forward since one side is just x+3

im unsure how you would work directly from (x+3)^2=11 otherwise

summer igloo
#

also btw sorry if i get like mad i dont do that because i mean any of it i do that because asking for help is actually more stressful than doing the math for hours

dense jay
#

its okay

devout snowBOT
#
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devout snowBOT
#
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plucky junco
#

How do I graph y = absx over x 🤣

devout snowBOT
graceful stone
#

I think you did a good job here

plucky junco
#

My friend did this for me, but I still don’t know How he get there

graceful stone
#

Check what happens you plug in positive numbers in |x|/x

#

And then check what happens when you plug in negative numbers

plucky junco
#

Yeah I did it from 1 to 3, but what about the two holes in the middle, how did he get there

graceful stone
#

So the function is undefined at 0

#

So for all positive numbers, we have 1

#

And all negative, we get -1

#

So right up to x=0, we get those values

#

From both left and right

#

So we get those discontintuity points

plucky junco
#

What if I just don’t draw the holes🤣

#

I thought it’s undefined

graceful stone
#

The holes are just showing we don't have a value there

plucky junco
#

Ok thanks bro

graceful stone
#

Np

plucky junco
#

.close

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#
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#
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restive river
#

help

devout snowBOT
restive river
#

i dont get what im doing wrong

#

something ive annotated is wrong

#

idk how tho

#

the 2.52 is wrong btw

devout snowBOT
#

@restive river Has your question been resolved?

devout snowBOT
#

@restive river Has your question been resolved?

devout snowBOT
#

@restive river Has your question been resolved?

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#
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#
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restive river
#

Can someone tell me about what some popular yr 7 math topics that students tend to get lower grades

dapper fable
#

line equations probably

lament kraken
#

Coordinate geometry

dapper fable
#

and sequences (for some people)

devout snowBOT
#

@restive river Has your question been resolved?

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#
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#
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echo fox
#

how thita + alpha 180?

devout snowBOT
solar goblet
#

the figure doesn't even seem relevant to the question

#

AB tangent at B, not A. likewise with CD

orchid axle
#

gonna use this property

echo fox
orchid axle
#

angle

tall stirrup
#

no, its angle subtended by minor arc

echo fox
tall stirrup
#

yes

echo fox
echo fox
tall stirrup
#

leave that property alone

#

and draw OB and OD, O being the centre

#

let me draw it

#

OP are u there with me?

echo fox
#

yep

tall stirrup
#

I forgot to label O, but you get it right?

#

anyways, <OBD = |90 - alpha|, why?

echo fox
tall stirrup
#

yeah

#

so, its actually absolute value, because alpha can be acute as well

#

but anyways, lets go according to figure and assume alpha is obtuse

#

So, <OBD = alpha - 90

#

now < OBD = < ODB, why?

echo fox
tall stirrup
#

yeah, because OBD is isoceles triangel

#

*triangle

#

so <ODB = 90 - alpha

#

now <ODB + < MDC = <ODC = 90deg

#

do you get this?

echo fox
tall stirrup
#

yeah kind kind of, but don't forget the absolute value

echo fox
tall stirrup
#

ODB = alpha - 90 and MDC = theta

#

oops

#

yeah, alright

#

so, alpha - 90 + theta = 90

#

badaboombadabig

tall stirrup
echo fox
#

but still angle ODB is also 90 - theta, and its equal to angle OBD , so wont I end up with theta equal to alpha?

tall stirrup
#

if one of them is acute, the other would be obtuse, so, one of the mod opens negative

#

we're using modulus because geometrical angles can't be negative(in this case)

tall stirrup
#

if alpha > 90 and theta > 90 is not possible, you can try and draw a few, so one of them has to be equal to less than 90

#

I think that specific proof of this can be proved (by contradiction ig), but I'm not in mood of going down that rabbit hole

echo fox
#

Thanks a lot tho

#

.close

devout snowBOT
#
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#
Available help channel!

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echo fox
#

how the raitio is 1 : 2

devout snowBOT
stoic pasture
valid silo
#

since EA=AC/2

#

AD=AB/2

#

and similarity

small badge
#

midpoint theorem

devout snowBOT
#

@echo fox Has your question been resolved?

devout snowBOT
#
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native stone
#

we gotta solve the integral

devout snowBOT
native stone
#

thats all

#

what kind of substitution should i do

pure flower
#

whats the parts a b c

#

etc

native stone
#

huh?

#

i dont understand what you're asking

pure flower
#

just wanna solve the integral?

native stone
#

yep

pure flower
#

oh those are options lol

native stone
#

yea its multiple choice

safe fractal
#

So there's a way to cheat this

#

it's mathematically legal

native stone
#

yea i know

#

just take the derivative

#

of each

safe fractal
#

yup

native stone
#

i dont wanna do that tho

safe fractal
#

it's slow

#

but it works

native stone
#

its also really slow

native stone
safe fractal
#

Maybe that's the intended route given it's multiple choice

#

I've had proffesors do that

native stone
#

nope

#

it isnt

#

the exam has so many question to solve in 4 hours

#

that it cant be that method

safe fractal
#

Honestly, deriving them is faster than integrating

native stone
#

its not useful for me tho

#

the point is the learn some methods to solve these types of exercises

#

for the exam

native stone
safe fractal
#

So how would you approach integrating it?

native stone
#

idk

#

this has obviously something to do with substitutions

#

its just hard to see which one would work and which wouldnt

safe fractal
#

hmmm just throwing out some ideas, I'd start by maybe rewriting +1 as - 1 + 2

native stone
#

yea i thought of that first too

safe fractal
#

and then substituting e^x - 1 as something

native stone
#

but its a sqrt

#

so it wouldnt help

fierce girder
#

let me try

#

have u tried deriving all options?

#

@native stone

native stone
#

i wont do that

#

i can tell you the answer if thats what you want tho

fierce girder
#

why

#

no i dont want that

native stone
fierce girder
#

please dont tell me

fierce girder
native stone
#

also, look at what i would have to derivate

fierce girder
#

I know

#

its a beast

native stone
#

its a pain to derivate all of those 8 answers

fierce girder
#

derivation takes a long time

safe fractal
#

I mean, through elimination I can already tell which the answer isn't...

fierce girder
#

but it has a definite path to be followed which is very easy

native stone
#

this whole book is like this and ive never done that so i wont start now

safe fractal
#

Integrating this is a bit tricky

native stone
#

plus, this is considered an easy exercise in this book

snow raptor
#

easy

fierce girder
#

wait

native stone
fierce girder
#

its either d or e

#

right

snow raptor
#

sub e^x and see where it takes you

native stone
snow raptor
#

you will have to take many subs after this

native stone
#

right

#

so you would get sqrt of (u+1/u^2(u-1)) du

#

right?

snow raptor
#

in denominator :- u * sqrt(u-1)

native stone
#

right right

snow raptor
#

take another sub here

native stone
#

wait no

snow raptor
#

sqrt(u+1)

native stone
#

why the -

snow raptor
#

actually no

#

this is time wasting

native stone
#

wiawt one sec

#

did you get this?

#

i forgot to put the integral and the du after

#

but it doesnt matter

fierce girder
#

oops

#

i see a mistake

native stone
#

2du = e ^x/2 dx

fierce girder
#

all better now

native stone
#

if you wanna do it like that

fierce girder
#

I had something in mind

#

not sure it would help

#

actually I dont think its gonna help at all

native stone
#

nope

fierce girder
#

bruh

#

dam

#

mission failed

#

sorry

safe fractal
#

You could try doing something wild like (e^x + 1) / (e^x - 1) = u^2 and see where that substitution gets you

fierce girder
#

ALRIGHT

snow raptor
#

the derivative is bad

fierce girder
#

nah I ain't doing all that

safe fractal
#

This integral isn't easy

#

The solution is wild and doesn't simplify well according to the online calculators

#

they get something wild

snow raptor
#

try bringing it to a form that can be integrated using partial fraction decomposition

snow raptor
#

the final answer is having some terms such as arctan

#

you use some properties to bring it to arccos

fierce girder
snow raptor
#

idk what they are

fierce girder
#

there is 1

#

I was thinking about it

#

but I failed at doing it

#

if u remember

native stone
#

nah

#

i think i almost solved it

fierce girder
native stone
#

these are some wild ideas that you two are having tho

safe fractal
#

Introduce hyperbolic cos

#

lmao

native stone
#

thats insane

safe fractal
#

Insane enough to work

fierce girder
#

the problem with this is that we have e^x - 1

#

not 1 - e^x

native stone
safe fractal
native stone
#

right right

fierce girder
#

sinh(x) = e^x - e^(-x)
cosh(x) = e^x + e(-x)
tanh(x) = sinh(x)/cosh(x)

native stone
#

i need help with something

fierce girder
#

= (e^(2x) + 1)/(e^(2x) - 1)

#

i dont see it

#

wait

#

what if

#

u = x/2

native stone
#

is arcsin (-e^-x)=arccos e^-x?

fierce girder
#

try that

native stone
#

dude

#

i almost solved it

fierce girder
#

absolutely not

#

look

#

let

native stone
fierce girder
#

y = e^(-x)

#

ur saying

#

arcsin(y) = arccos(-y)

fierce girder
native stone
#

backwards

#

arcsin(-y)=arccos y

fierce girder
#

i dont see it tho

#

wait let me try

native stone
#

y is in between 0 and 1

fierce girder
#

arcins(e^-x) = arccos(sqrt(1 - e^(-2x)))

#

yeah

#

remember

#

sinx = sqrt(1 - cos²x)

#

so arcsin(x) = arccos(sqrt(1-sin²x))

#

yea

#

u gotta convert the values from sin to cos

native stone
#

im going to the bathroom

#

but here

fierce girder
#

k

native stone
#

just so that you dont tire yourself with funky ideas anymore

#

take a glance at this

#

its not solved

#

completely

fierce girder
#

i cant read

native stone
#

but thats where i got

fierce girder
#

ur handwriting

#

but sure

#

I believe in you

native stone
#

well then

#

too bad

fierce girder
#

I'm sorry, how the actual fugh

native stone
#

you amplify the whole fraction by e^x +1

fierce girder
#

right

native stone
#

so multiply both the nominator and the denominator

#

by e^x +1

fierce girder
#

right

native stone
#

yup

#

any other questions?

fierce girder
#

nah

#

so were u multiplying it by

#

sqrt(e^x + 1) or e^x + 1

native stone
#

sqrt of it

fierce girder
#

that makes sense

#

a lot of sense

native stone
#

mhmm

fierce girder
#

I see a path

#

of light

#

now

#

ahhh

native stone
#

so you got the rest of my solution?

#

or did my handwriting throw you off?

#

cuz that was the first line

#

and it took you 10 mins to decipher it

fierce girder
fierce girder
fierce girder
native stone
#

your assumption was correct

native stone
fierce girder
#

I see it

#

I haven't tried yet

#

let me try

native stone
#

aha

#

sure

#

but ill have to go in 10 mins

fierce girder
#

dont expect results

native stone
#

the only thing that is off is the arcsin instead of arccos

#

and i looked at the answer, and d) is the correct answer

#

so i just gotta figure that out

#

if you've still got questions after i end this then you can message me in private

fierce girder
#

ok

#

how

#

I understand the top line

#

but how'd u split it up into two different integrals

native stone
#

?

#

split it into two yourself

#

u will see that the u dissapears

fierce girder
#

how

native stone
#

huh?

fierce girder
#

u cant split this integral

native stone
#

maybe you just have been taught this

#

but you can

fierce girder
#

right

#

how

#

OH WAIT

#

I SEE

#

the + sign

#

damn

native stone
#

aha

fierce girder
#

mb

native stone
#

no prob

fierce girder
#

i didn't see that

native stone
#

thats fine

fierce girder
#

bruh I just looked at it

#

I cant tell which one is u and which is 1

#

the left one is u

native stone
#

i did some fancy thing somewhere in there

fierce girder
#

and the right one is 1

#

I see it

#

u canceled the u with the u

#

and u kept the 1

#

the left is easy to integrate

native stone
#

aha

fierce girder
#

u simply use

native stone
#

good job

fierce girder
#

u = secθ

native stone
#

no dude

#

theres a formula

fierce girder
#

yes

#

dude

#

u use that

#

and thats all

#

so u evaluate

native stone
#

nope

fierce girder
#

secθ dθ

#

which is

#

ln|secθ + tanθ| + C

native stone
#

yea yea i know what sec alfa is

fierce girder
#

now u desubstitute

native stone
fierce girder
#

how

#

u basically just memorize the answer

#

thats ur simpler way?

native stone
#

here

#

take a look at this

native stone
#

i gotta go now tho

#

.close

devout snowBOT
#
Channel closed

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fierce girder
#

did it

native stone
#

right

#

sure that works

devout snowBOT
#
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restive river
devout snowBOT
restive river
#

What did I do wrong?

sand quarry
restive river
tall stirrup
#

,rccw

woven radishBOT
restive river
#

I already understand, but thanks guys

#

.close

devout snowBOT
#
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sand quarry
# restive river Sowwy

Sowwy as in "Sowwy I will give a translation right now" or "Sowwy I can't translate this"?

#

oh

#

okay nevermind

tall stirrup
#

o7

devout snowBOT
#
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plucky nexus
#

Need to solve this though l'hopital's rule

solar goblet
#

ctg is cotangent right?

plucky nexus
#

Yes

solar goblet
#

well what have you tried?

plucky nexus
#

i`ve got lim(-(x\sin^2(x))) and then got stuck

#

Don`t sure how to derivative it further

solar goblet
#

differentiate it again

plucky nexus
#

Can I really differentiage sin^2(x) ? or I shoud use Power Reducing Formula?

plucky nexus
#

Something like that ?

olive snow
#

And what is bottom ?

plucky nexus
#

2sin(x)*cos(x) ?

solar goblet
#

which is sin(2x)

#

as x approaches 0, what does sin(2x) approach?

plucky nexus
#

0

solar goblet
#

you now got -1/0

plucky nexus
#

-infinity?

solar goblet
#

well you could say that yeah

olive snow
plucky nexus
olive snow
#

So yeah -1/0+

#

Indeed -inf

plucky nexus
#

Yes, that was the answer. Thank you a lot

#

.close

devout snowBOT
#
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