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Log & expo functions help (1 Viewer)

Thread starter beeang
Start date Jan 19, 2018

B

beeang

New Member

#1

Without using integration by parts? (that's what has come up when I've searched how to integrate ln(x)

J

jathu123

Active Member

#2

$$ \noindent Volume of revolution about the y-axis: $ \pi \int_{y_1}^{y_2} x^2 $ d$y \\ \\ $ So making $x$ the subject, we get $ x= e^{y} \\ \\ \therefore V=\pi \int_{1}^{3}e^{2y} $ d$y \\ \\= \left [ \frac{\pi}{2}e^{2y} \right ]_{1}^{3} \\ \\ = \frac{\pi}{2}e^2\left ( e^4-1 \right ) $ units$ ^3$

Last edited: Jan 19, 2018

B

beeang

New Member

#3

Wait isn't it x^2?

So its e^2y?

And the pi as well somewhere?

J

jathu123

Active Member

#4

beeang said:
Wait isn't it x^2?

So its e^2y?

And the pi as well somewhere?

oh yes my bad, forgot to square it
and the pi
smh forgot too much

HeroWise

Active Member

#5

This is just for reference if others need help

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