# Thread: Simple Integration

1. ## Simple Integration

Not sure how to do the following integral, is it integration by parts?

$\int{\frac{e^{{\frac{-1}{x}}}}{x^2}dx}$

2. Naah, try a substitution. Note that $d/dx (1/x) = -1/x^2$.

3. Hello, Jason Bourne!

$\int{\frac{e^{\text{-}{\frac{1}{x}}}}{x^2}dx}$

We have: . $\int e^{\text{-}x^{\text{-}1}}\left( x^{\text{-}2}\,dx\right)$

Let: . $u = \text{-}x^{\text{-}1}\quad\Rightarrow\quad du \:=\:x^{\text{-}2}dx$

Substitute: . $\int e^u\,du\quad\hdots\quad Got\; it?$

4. Thank You very much, it's so obvious now.