# Math Help - Integration

1. ## Integration

Is it possible to integrate (t^2e^-t)/(t + 1)??

2. yes,,you can use quotient rule...

3. Isn't quotient rule for differentiation??

Isn't quotient rule for differentiation??
$\int t^2 e^{-t} (t+1)^{-1}$

$\int t^2 e^{-(t+1) + 1} (t+1)^{-1}$

$e \int t^2 e^{-(t+1) } (t+1)^{-1}$

Let $u = t + 1$

$e \int (u-1)^2 e^{-u } (u)^{-1}$

$e \int \frac{ u^2 - 2u + 1 }{ ue^u }$

$e \int \frac{ u}{ e^u } - 2e \int e^{-u} + e \int (ue^u)^{-1}$

All of the above can be evaluated fairly easily. Use By Parts for most of them.

5. (ue^u)-1

uumm how do you integrate that one??

(ue^u)-1

uumm how do you integrate that one??
I lied, we cannot use by parts on that particular integral. It cannot be evaluated in elementary functions: Wolfram Mathematica Online Integrator

It's defined as $Ei(-x)$

So it would appear as if I have taken you down a path where you can integrate the integrand but not in terms of elementary functions. I'm sure an alternative approach will yield a result that can be fully explained in terms of elementary functions (i'll think of another way to start it off).

Calling...Simplependulum!!