# integration by parts

• Oct 22nd 2009, 04:08 AM
nazli1989
integration by parts
Hi, i came across this weird question that didn't look like the usual integration by parts question.... the question was to integrate e^-t^3 dt.. between the limits of infinity and x.

The first line in the answers was the only line that caught me off guard.
It was, f(x)= (integral sign between infinity and x) -1/3t^2 - 3t^2e^-t^3 dt

please could you explain this to me, thank you
• Oct 22nd 2009, 04:29 AM
tonio
Quote:

Originally Posted by nazli1989
Hi, i came across this weird question that didn't look like the usual integration by parts question.... the question was to integrate e^-t^3 dt.. between the limits of infinity and x.

The first line in the answers was the only line that caught me off guard.
It was, f(x)= (integral sign between infinity and x) -1/3t^2 - 3t^2e^-t^3 dt

please could you explain this to me, thank you

There's nothing to explain since it makes no sense: are you telling us that

$\displaystyle \int_{x}^{\infty}e^{-t^3}dt=\int_{x}^{\infty}\left(-\frac{1}{3}t^2-3t^2e^{-t^3}\right)dt\,\,??$

What book is this from? Is the above what you wanted to say?

Tonio