# Thread: Integral of e^(-x)

1. ## Integral of e^(-x)

I was wondering what is the Integral of e^(-x)?

2. Originally Posted by chevy900ss
I was wondering what is the Integral of e^(-x)?
$-e^{-x} + C$

3. Originally Posted by chevy900ss
I was wondering what is the Integral of e^(-x)?
Try to make this subtitution $-x=u$

$\int {{e^{ - x}}dx} = \left\{ \begin{gathered}
- x = u, \hfill \\
dx = - du \hfill \\
\end{gathered} \right\} = - \int {{e^u}du} .$

4. Just in case a picture helps...

... where (as usual) ...

represents the chain rule for differentiation - straight continuous line differentiating down (integrating up) with respect to x, the straight dashed line similarly but with respect to the dashed balloon expression.

Don't integrate - balloontegrate!

Balloon Calculus Forum

5. Ok thanks for the help.