I didn't know I had a math packet to do over the summer, so now I'm rushing to get it all done before I have my first class of pre-calc and I'm really stumped with this one problem. I need to simplify this:

(2^-2 + 4^-2) ^ -1

So the 2 and the 4 are both to negative exponents, then the whole thing is in parenthesis and raised to the -1 power. I tried moving the whole equation down and getting rid of the -1 exponent, like this:

1/(2^-2 + 4^-2)

Then I realized that the numbers underneath would have to go up, to give me

2^2 + 4^2 = 4 + 16 = 20.

BUT then I realized I might have done it all wrong, and needed to instead distribute the exponent outside the parenthesis. Which way is right, and if it's this second way, how do I do it?