A firm uses two factors of production: x1 and x2. The cost of each unit of x1 is w1, and the

cost of each unit of x2 is w2. The firm seeks to produce a unit of output. In each one

of the following cases, find the cost function c (w1, w2, 1).

a) f (x1, x2) = min {2x1, 3x2}.

b) f (x1, x2) = 2x1 + 3x2.