Use the fact that 3~J64 = 4 and the derivative of the function f(x) = V3? to estimate 3V 62. Show your work carefully. The profit function for a skateboard manufacturer is given by P(x) = ().3x2 + 30x 250, where x is the number of skateboards produced and sold. For what values of x is this business profitable (prot is positive)? a b. Find the marginal profit function. c Find and interpret the marginal profit after manufacturing and selling 20 skateboards. d Find and interpret the marginal profit after manufacturing and selling 60 skateboards