The graph of the function f(x) = (x − 3)(x + 1) is shown. On a coordinate plane, a parabola opens up. It goes through (negative 1, 0), has a vertex at (1, negative 4), and goes through (3, 0). Which describes all of the values for which the graph is positive and decreasing? all real values of x where x < −1 all real values of x where x < 1 all real values of x where 1 < x < 3 all real values of x where x > 3