3) Consider the maximization model F ( X , , X 2 , X 3 , X 4 ) = XX, + x , x, + a,x, +azX2 -X3 + 04 subject to *, txz -a, x, tax = 0 10 a) Write out all the first and second-order conditions. (You do not need to solve these conditions.) 10 b) What does the maximization problem itself tell us about the signs of each of the following partial derivatives