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Integration by parts
#6
stuck on another problem.
Integrate:
1/(x * sqrt(x + 1))

Used u sub setting:
u = sqrt(x +1)
x = u^2 - 1
dx = 2udu

I end up with: -16/(u * (u^2 - 1))
Move out -16, and split u^2 -1 into (u + 1)(u - 1)
Used partial fractions; got A = -1, B = 0.5, C = 0.5.

I get: -lnabs(u) + 1/2lnabs(u -1) + 1/2lnabs(u + 1) + C
Substitute x back in, multiply by the -16 I moved out, and I get:
16lnabs(sqrt(x + 1) - 8lnabs(sqrt(x + 1) - 1) - 8lnabs(sqrt(x+1) +1) + C
And that seems to be wrong.

Found my error, forgot to factor out u.
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Messages In This Thread
Integration by parts - by Imagine - 2012-11-05, 01:40 AM
Integration by parts - by Locked - 2012-11-05, 02:01 AM
Integration by parts - by Imagine - 2012-11-05, 02:12 AM
Integration by parts - by Imagine - 2012-11-26, 09:38 PM
Integration by parts - by Locked - 2012-11-26, 11:04 PM
Integration by parts - by Imagine - 2012-11-27, 12:09 AM
Integration by parts - by Imagine - 2012-12-10, 09:52 PM
Integration by parts - by hadriel - 2012-12-11, 07:50 AM

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