Perform a first derivative test on the function f(x) = x√/81-x²; [-9,9]. a. Locate the critical points of the given function. b. Use the first derivative test to locate the local maximum and minimum values. c. Identify the absolute minimum and maximum values of the function on the given interval (when they exist). a. Locate the critical points of the given function. Select the correct choice below and, if necessary, fill in the answer box within your choice. OA. The critical point(s) are located at x= | (Use a comma to separate answers as needed.) B. There are no critical points.