Question regarding simplifying [(x^2 + 4)2 - 2x(2x)] / (x^2

[Lime]

How can you go from this:

[(x^2 + 4)2 - 2x(2x)] / (x^2 + 4)^2

To this:

[8 - 2x^2] / (x^2 + 4)^2

I have no idea where the "- 2x(2x)" went.

 

[Steem]

-2x(2x) gives you -4x^2. When you subtract it from the 2x^2 you get -2x^2.