# Homework Help: Integration by parts

1. Sep 22, 2008

### duki

1. The problem statement, all variables and given/known data
Integrate $$\int{\frac{lnx}{x^4}dx}$$

2. Relevant equations

3. The attempt at a solution

I get this:
$$u = ln x, du = \frac{1}{x}$$
$$dv=x^4, v=\frac{x^5}{5}dx$$
$$\frac{(lnx)x^5}{5}-\int{\frac{x^5}{5}*\frac{1}{x}dx} = \frac{(lnx)x^5}{5}-\frac{6x^6}{5}dx}$$

Am I doing this right?

2. Sep 22, 2008

### JG89

Your dv should be the integral of 1/x^4, not x^4.

3. Sep 22, 2008

### duki

Hmm, ok. So what would be v?

4. Sep 22, 2008

### JG89

The integral of x^(-4), which is 1/-3 * x^-3

5. Sep 22, 2008

### duki

Oooh, ok. Thanks for your help!