Should this be $\int u^2 \sqrt{u+1} du$ after substitution of $u=e^x$?

Should this be $\int u^2 \sqrt{u+1} du$ after substitution of $u=e^x$? http://www.wolframalpha.com/input/?i=integrate+%28exp%28x%29%29^2*sqrt%281%2Bexp%28x%29%29 -> show steps ->3rd row

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1 Answer

No, when you do the substitution $u=e^x$ then $du=e^x dx$ so $dx=du/u$ which is why it's $u$ and not $u^2$.

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By the way, I suggest you to increase your accept rate. –  Seyhmus Güngören Aug 6 '12 at 20:23
thanks. I missed it. –  laovultai Aug 6 '12 at 20:24
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