A firm has the following short-run production function (where L = Labor and Q = Output):
Q = 10L - 0.5L2
Suppose that the output can be sold for $10 per unit. Further assume that the firm can obtain as much of the variable input (L) as it needs at $20 per unit.
a) Determine the marginal revenue function.
b) Determine the value of L that maximizes profits.