# Math Help - Compute this integral.

1. ## Compute this integral.

Integral from plus to minus infinity of x(1/3)^x with repect to x.

thanks

2. Originally Posted by feyomi
Integral from plus to minus infinity of x(1/3)^x with repect to x.

thanks
$\int_{-\infty}^{\infty} x \cdot 3^{-x} \, dx = \int_{-\infty}^{0} x \cdot 3^{-x} \, dx + \int_{0}^{\infty} x \cdot 3^{-x} \, dx
$

should be easy to show the integral from $-\infty$ to $0$ diverges