# Homework Help: Difficult Distribution Function

1. Oct 15, 2011

### trojansc82

1. The problem statement, all variables and given/known data
∫3/43x2e-(x/4)3

2. Relevant equations
F(x) = 0xf(t) dt

3. The attempt at a solution

The solution is 1 - e-(x/4)3

I have tried integrating but I am not able to arrive at the solution....

What is the indefinite integral of e-(x/4)3?

2. Oct 15, 2011

### LCKurtz

It is hard to make out what your equations actually are. But you aren't asked to integrate e-(x/4)3. You have an x2 in there. Basically, ignoring the constants you have an integral of the form

$$\int x^2e^{-x^3}\, dx$$

and you need to do a substitution similar to u = x3, du = 3x2dx but modified to include your constants.