Use the function below to answer the questions. f(x)=3 x^{1 / 3}-x ^^20(a)^^20Find^^20f^{\prime}(x)=-----. (b) Find the x values of all of the critical points. Enter your answers as a comma

separated list. x = _________. (c) Find the global maximum and global minimum on the interval -1<=x<=7. global maximum at x = _______. global minimum at x = ________.