(a) Approximate the true marginal cost function MC(q) with a linear approximation if it is known that MC(1) = 4 and MC(3) = 8.

(b) How is the cost function related to the marginal cost function?

(c) Determine the cost function C(q) associated with the marginal cost function if it is known that the costs are 20 when producing 2 units (i.e., C(2) = 20).

Please solve step by step, thank you!