4. Sketch a graph of a function y = f(x) that satisfies the following properties. a) f(x) is decreasing on (-0o, -1) b) f (x) is increasing on (-1, 00) c) f (x) is concave up on (-0o, 0) d) f (x) is concave down on (0, co) 2 1 -4 -3 -2 -1 2 3 -1 -2 -3 - -4