Determine whether the following production functions have

Question

Determine whether the following production functions have Constant, Decreasing or Increasing Returns to Scale (a formal proof is required).

(a) F (K,L)= K^3+L^3

(b) F (K,L)= K^2/L^3

(c) F(K,L)= 2K^2+3L^2/ K+L

(d)F(K,L)=K^aL^1-a (where "a" is a parameter)