(2x+1)(2x+1)+x^2=40,000, solve for x.

You can solve it by using the quadratic formula too.

http://www.youtube.com/watch?v=O8ezDEk3qCg

The the first step here is is to simplify the left side of the expression.

4x^2+4x+1+x^2=40000

5x^2+4x-39999=0

The easiest way to solve this is to graph it.  I like the free graphing calculator at desmos.com

It reveals two solutions of x=89.04  x=-89.84