Question

The graph of the function f(x) = –(x + 3)(x – 1) is shown below.

On a coordinate plane, a parabola opens down. It goes through (negative 3, 0), has a vertex at (negative 1, 4), and goes through (1, 0).

Which statement about the function is true?

The function is positive for all real values of x where
x < –1.
The function is negative for all real values of x where
x < –3 and where x > 1.
The function is positive for all real values of x where
x > 0.
The function is negative for all real values of x where
x < –3 or x > –1.

Answer 1

Answer: Choice B

Reason:

The graph is an upside down parabola. The parabola opens downward. The x-intercepts are at -3 and 1. Between these roots the parabola is above the x axis, so the function is positive. We write y > 0 when -3 < x < 1.

On the other hand, y < 0 when either x < -3 or x > 1. This points us to choice B