Suppose that the demand for x units of a product is x = 9,000 – 90p where p dollars is the price per unit. Then the consumer expenditure for the product is E(p) = px = p(9,000 – 90p) = 9,000p – 90p2....

Extracted text: Suppose that the demand for x units of a product is x = 9,000 – 90p where p dollars is the price per unit. Then the consumer expenditure for the product is E(p) = px = p(9,000 – 90p) = 9,000p – 90p2. What is the instantaneous rate of change of consumer expenditure with respect to price at the following values? (a) any price p | (b) p = 5 (c) p = 40