http://i36.tinypic.com/rsas13.jpg

Thanks in advance for any help!

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- Oct 9th 2009, 07:14 AMjanedoeIntegration w/ u-substitution, work is inside
http://i36.tinypic.com/rsas13.jpg

Thanks in advance for any help! - Oct 9th 2009, 07:22 AMpflo
Why use u-substitution on this problem?

$\displaystyle \int{t^2(t-\frac{2}{t}) dt}$

$\displaystyle \int{(t^3-2t)dt}$

$\displaystyle \frac{t^4}{4}-t^2+c$

I suppose if you HAVE to use u-substitution, you could let $\displaystyle u=t^2$ instead.

That would give you the following integral:

$\displaystyle \int{(\frac{u}{2}-1)du}$ - Oct 9th 2009, 07:24 AMjanedoe
- Oct 9th 2009, 07:32 AMpflo
I edited my original reply to include a method where you could use u-substitution.

One note: When using u-substitution, always look for the derivative of u (the one with the original variable) to cancel out. In this case, you identified the problem with the substitution you originally did - couldn't cancel out the t's. But with $\displaystyle u=t^2$ the derivative would include a 't' which WOULD cancel out.