I'm having difficulty evaluating the following limits:

lim x->4

2-√x

_______

3-√2x+1

and

lim x->0

2^2x - 2^x

___________

2^x-1

I'd really appreciate any help with these. I know I need to multiply by the conjugate radical in the first one, but after that I'm stuck. With the second, I'm really not sure what to do. Thanks in advance :)