Simplify the following equation for n 1

1. Sep 26, 2008

roeb

1. The problem statement, all variables and given/known data
show $$\frac{1}{(n-1)^2} - \frac{1}{n^2} about= \frac{2}{n^3}$$
n >> 1

2. Relevant equations

3. The attempt at a solution
The first thing I tried was to put the expression all into one term.
so I got $$\frac{-n^2 + 3n - 1}{n^3 - 2n^2 + n}$$
Unfortunately, I'm not sure where to go next with this... I assume it has to do with n >> 1. But I really don't see how they get 2/n^3 if anything I would think -1/n ...

2. Sep 26, 2008

Redbelly98

Staff Emeritus
Re: Simplification

How did you get your expression (in "attempt at a solution" section)? Did you try to get a common denominator?

3. Sep 26, 2008

Redbelly98

Staff Emeritus
Re: Simplification

Wait, I see your problem.

The 2nd term in the original expression is 1/n2, not 1/n

4. Sep 26, 2008

roeb

Re: Simplification

My apologies, I just realized I did the incorrect substitution from the original problem. I incorrectly transcribed 1/n. It should have been 1/n^2.

I figured it out now, thanks.