Having a difficult time trying to understand this. Any help would be appreciated.

The cost, in thousands of dollars, of airing x television commercials during a sports event is given by C(x) = 20 + 2,000x + 0.02xz. (a) Find the marginal cost function C'(x). HINT [See Example 1.] C'(x) = 2000 + 0.04): i Use it to estimate how fast the cost is increasing when x = 4. 2000.16 thousand dollars per television commercial Compare this with the exact cost of airing the fth commercial. The cost is going up at the rate of $ 2000+0.4x per television commercial. The exact cost of airing the fth commercial is $ 10020 X . Thus, there is a difference of $ 2000.18 x (b) Find the average cost function (3, and evaluate E(4). HINT [See Example 2.] em = % + 2000 + 0.02x _ V C(4) = 2005.08 'f thousand dollars per television commercial What does the answer tell you? The average cost of airing the rst four commercials is $ 200508 X per commercial