a For what values of x is the function f x 1x 251 differentiable Enter your answer using interval notation X X Find a formula for f f x b Sketch the graph of f 20 10 40 X 20 X f x 30 20 Sketch the graph of f 10 10 30 if x if x f x 40 20 20 40 10 20 20 X X 40 10 40 f x 20 WM 10 10 10 10 f x 40 20 20 40 20 40 20 f x 10 10 10 f x 20 10 10 20 5 10 10 20 X 20 f x 30 VAV 10 20 10 10 10 20 30 f x 20 10 10 20 10 10 20 20 9