no need to show work

Question 6 5 pts 1.1 1.2 1.3 "Quiz4Graphs RADO X 10000 y f(x)-2-31.x3-26-x2+1440-x Suppose f(x) = (1/5)x^5 - 31x^3 - 26x^2 + 1440x models the profit gained in hundreds of dollars from making and selling "x" airplanes in a month. The manufacturing company would like to MAXIMIZE profit. Johnny know that the firstderivative is helpful for finding relative maximum and relative minimum points. He finds: f ' (x) = x^4 - 93x^2 - 52x + 1440 Using the factored form of f' (x), he sets (x + 8)*(x+ 5)*(x - 4)* (x - 9) = 0. According to Johnny's equation, the manufacturing company will maximize profit at what dollar amount (in a month)? O $64.80 O $3564.80 O $6480.00 O $356,480.00