Given the following revenue and cost functions, find the x-value that makes profit a maximum. (Recall that profit equals revenue minus cost.) R(x)=58x-2x^2; C(x)=21x+109

Solution:

                               Profit = 58x-2x^2 - 21x - 109

                                          = -2x^2 + 37x - 109

  Maximum at:     x = -b/2a = 37/4 = 9.25