# Homework Help: Integrating Rational Function

1. Jan 31, 2013

### whatlifeforme

1. The problem statement, all variables and given/known data
integrate the following:

2. Relevant equations
∫(x/(x-1)^3

3. The attempt at a solution
i've tried u-substitution, finding an inverse trig function that matched the formula, and still can't figure out how to solve this problem.

u-subtitution for u=x gives the same problem. u-subsitution for x-1 gives du =1 which does not match the problem.

2. Jan 31, 2013

### Dick

u=(x-1) gives du=dx which does match the problem. If you are worried about the x in the numerator, if u=x-1, then x=u+1.

3. Jan 31, 2013

### Hysteria X

Its a fairly easy integral..dont go all complicated when you cant find the answer just stay on the ground bro :tongue2: sometimes few problems can be easily solved if you just view it from a different angle

this should work. you would get u+1/u^3 du which you split and integrate

4. Jan 31, 2013

### Ray Vickson

No, you will not get $$u + \frac{1}{u^3},$$ which is what you wrote! If you really mean $$\frac{u+1}{u^3},$$ use parentheses, like this: (u+1)/u^3.

5. Jan 31, 2013

### Dick

Good advice but use more parentheses. You could easily mistake u+1/u^3 for u+(1/u^3) when you meant (u+1)/u^3.

6. Jan 31, 2013

### Hysteria X

lol thanx for pointing it out..my bad :shy: