Hi! I need some help in the following problems.

1. What is the limit if n tends to infinity:

[(n+2) choose 2]/(n choose 2)]^n

2. Derivation

y=(4^x-x^4)/log(7)x; that is the seven-based log of x

3. Derivation

y=ln[e^x+e^(-x)]

4. Limit if x tends to zero

1/[e^(2x)-1]-1/2x

Thanks a lot.