Find all the local maxima, local minima, and saddle points of the function. f(x,y) = - 6x2 - 3xy - 8y2 + 72x + 79y + 4 ... Select the correct choice below and, if necessary, fill in the answer boxes to complete your choice. O A. A local maximum occurs at (Type an ordered pair. Use a comma to separate answers as needed.) The local maximum value(s) is/are. (Type an exact answer. Use a comma to separate answers as needed.) B. There are no local maxima. Select the correct choice below and, if necessary, fill in the answer boxes within your choice. A. A local minimum occurs at (Type an ordered pair. Use a comma to separate answers as needed.) The local minimum value(s) is/are. (Type an exact answer. Use a comma to separate answers as needed.) B. There are no local minima. Find the saddle points. Select the correct choice below and, if necessary, fill in the answer box within your choice. O A. A saddle point occurs at (Type an ordered pair. Use a comma to separate answers as needed.) B. There are no saddle points.

Find the values of x for which the given function is concave up, the values of x for which it is concave down, and any points of inflection. y = -x + 6x5 - 6x + 19 When is the graph of y concave up? OA. 0 4 O C. x>4 O D. x<0