Math 115 hw question. Im not sure how to solve please help explain I have a test on Tuesday

Question

Cost of Producing Surfboards

 The total cost C(x) (in dollars) incurred by Aloha Company in manufacturing x surfboards a day is given by the following function.

C(x) = −10x² + 500x + 110 where (0 ≤ x ≤ 15)



(a)

Find C '(x).

C '(x) = 

 

 (b)

What is the rate of change of the total cost (in dollars) when the level of production is 7 surfboards a day?

$  per surfboard

Answer 1

C'(x) = -20x + 500

C'(7) = -20(7) + 500