f(x)= 3x+2, x<0

Question

3, x=0
x^2+1, x>0

g(x)= -x+3, x<1
0, x=1
x^2, x>1

find

a) lim x->0+ g(f(x))
b)lim x->0- g(f(x))
c) lim x->1+ f(g(x))
d)lim x->1- f(g(x))

I am trying to understand these. Help appreciated. Have a test soon.