# Thread: Mathematical Simplification

1. ## Mathematical Simplification

Hello all. I was working through an example in my Physics book and am having trouble with the simplifying algebra (very rusty). I'll go ahead and skip forward to the step that's giving me trouble:

E = q/(4πεz^2) [ 1/(1-(d/2z))^2 - 1/(1+(d/2z))^2 ]

Sorry that's so hard to read on here. I basically need to find a common denominator and multiply everything through. It should eventually reduce to:

E = (1/2πε) qd/z^3

Thanks for your help!

2. Originally Posted by aktor
Hello all. I was working through an example in my Physics book and am having trouble with the simplifying algebra (very rusty). I'll go ahead and skip forward to the step that's giving me trouble:

E = q/(4πεz^2) [ 1/(1-(d/2z))^2 - 1/(1+(d/2z))^2 ]

Sorry that's so hard to read on here. I basically need to find a common denominator and multiply everything through. It should eventually reduce to:

E = (1/2πε) qd/z^3

Thanks for your help!
LCD:

$\displaystyle (1-\frac{d}{2z})^2(1+\frac{d}{2z})^2$

So,$\displaystyle \frac{q}{4\pi\epsilon{z}^2}\left[\frac{(1+\frac{d}{2z})^2-(1-\frac{d}{2z})^2}{(1-\frac{d}{2z})^2(1+\frac{d}{2z})^2}\right]$

3. Thanks! Temporary brain lapse.

4. Originally Posted by aktor
Thanks! Temporary brain lapse.
So, can you finish then?

5. Yeah. That was what I originally did, but when I looked back at my work I found a mistake that threw everything off at the end. Thanks for your quick reply.