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Mathematics 21 Online
nuts:

Integrate

nuts:

\[\int\limits \sqrt{\tan x} \text{ dx}\] @Vocaloid

nuts:

i'm completely stumped :(

imqwerty:

Write tanx in form of sin and cos and then substitute \(\sqrt{cosx}=t\) and proceed

bananas:

I'm just here to say yolo

imqwerty:

I'm thinking of a shorter way to do this

nuts:

\(\huge \int \frac{\sqrt[4]{1-t^4}}{t}\text{ dx}\) it's not working :(

Vocaloid:

it's a little tedious but I believe you can start by doing a u-substitution where u = sqrt[tan(x)] therefore making u^2 = tan(x) so we'd want to re-write the expression in terms of u only, so we need to convert the dx to a du 2u du = sec^2(x)dx [taking the deriv. of both sides] using the tan^2 and sec^2 identity 2u du = 1 + tan^2(x)dx since we have tan(x) again we can now re-write completely in terms of u 2u du = 1 + (u^2)^2 dx dx = 2u du / (1 + [u^4) so now the entire integral becomes integral of 2u * u du / (1 + u^4) (sorry for the sloppy notation)

Vocaloid:

interesting problem

nuts:

wow you actually tried to do it lol. i'll give it to you, you're on the right track, but this is the first of at least 5 more substitutions you have to do

Vocaloid:

I would much rather be doing this than a million rate of change problems, believe me

nuts:

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nuts:

are you sure about that?

nuts:

I think either mimi_x3 or lgbasallote claimed to have a shorter route, but as we both know both users are long gone :(

imqwerty:

I am getting \(\huge \int\limits_{}^{}\frac{- 2dt }{\sqrt[4]{1-t^4 }}\) after that substitution

nuts:

vocaloid would you prefer a troll geometry question

imqwerty:

\(tanx=t^2\) and this problem is over

nuts:

qwerty what's your final answer

imqwerty:

Wait a min

imqwerty:

That's what voca did..

Vocaloid:

disclaimer: not my idea but you can split integral of 2u^2 du / (1 + u^4) into [ (u^2+1) + (u^2 -1) ] / (1+u^4) then [ (u^2+1) ] / (1 + u^4)* + [(u^2 -1)] / (1+u^4)** then taking the left side * and dividing by u^2 gives: [ ( 1 + 1/u^2) ] / (1/u^2 + u^2) ] then apparently you can do another u-substition (they use z) where dz = 1 + 1/u^2 du and z = u - 1/u after a bit of messy algebra/substitution you get 1/z^2 + u = 1/sqrt(2) arctan(z/sqrt(2)) plug u back in for z and get 1/z^2 + u = 1/sqrt(2) arctan(/sqrt(2))

Vocaloid:

ugh the bb code messed up that last line

nuts:

hmm yeah i think you needa eat this geometry problem ;)

Vocaloid:

then you would repeat this process with the other half of the integral and get something like this

Vocaloid:

anyway if you have another one I'd love to take a look

nuts:

well this one is basic geometry, if that floats your boat. fiendishly difficult for "basic geometry" but it's just 9th grade level geometry if you wanna take a stab at it

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