Need help solving the integral: (x^2)/(2^x)

[deiru]

Homework Statement

solve the integral ∫[(x^2)/(2^x)]dx evaluating from infinity to 0

Homework Equations

The Attempt at a Solution

using integration by parts I get this: ([(ln(2)x]^2 + 2ln(2)x +2)/(2^x)[ln(2)]^3
and a really big headache

 

[sylas]

Homework Statement

solve the integral ∫[(x^2)/(2^x)]dx evaluating from infinity to 0

Homework Equations

The Attempt at a Solution

using integration by parts I get this: ([(ln(2)x]^2 + 2ln(2)x +2)/(2^x)[ln(2)]^3
and a really big headache

The headache will pass; and you earned it in a good cause. Your integration is correct.

All you need now is to figure the limit as x goes to infinite, and the value when x is zero.

Well done -- sylas

 

[andylu224]

This Integration Technique might be useful in your case:

http://en.wikipedia.org/wiki/Integration_using_parametric_derivatives