For the function below, find the value(s) of x in which f (x) = 0. f( x ) = (x2 -1) (x2 -,5) The values are (Use a comma to separate answers as needed. Round to three decimal places as needed.)9x - 8 The total cost (in hundreds of dollars) to produce x units of a product is C(x) = 8x + 1 Find the average cost for each of the following production levels. a. 20 units b. x units c. Find the marginal average cost function. The average cost for 20 units is $ per unit. (Round to the nearest hundredth as needed.)