I need more Calculus help!

I don’t have any idea how to do these. Help would be very much appreciated.

1. a)Find the intervals on which f is increasing or decreasin
b)Find the local maximum and minimum values of f
c)Find the intervals of concavity and the inflection points

f(x)=(x^2) / ((x^2) + 3)

2.Find the limit using l’Hospital’s rule where appropriate unless it’s easier another way.

lim (as tapproaches 0) ((e^3t)-1) / t

3.^^^Same as 2^^^

lim (as x approaches infinity) (xe^(1/x)) – x