Step-by-step explanation:
The problem requires replace the input of labor and capital in the respective functions and compare the output with 48 (required units).
(a) Q=9L + 5K with the input (L,K)=(3,12) gives
Q= 9*3 + 5*12 = 27+60 = 87 so the production of 48 units is feasible but inefficient. It is produced more units than required.
(b) Q = 4KL+L-6
Q= 4*12*3 + 3 - 6= 141 so, the production of 48 units is feasible but so inefficient.
(c) Q = 8KL
Q = 8*12*3 = 288 the production of 48 units is feasible but very inefficient.
(d) Q = min{14L,2K}
Q = min{14*3, 2*12} = min{42, 24} = 24 (the minimum value between 42 and 24). So, the production of 48 units is not feasible with this production function and the given input.