Answer:
The x-intercepts are (-2, 0) and (4, 0). I know this because it's written in intercept notation. To find the y-intercept we'll expand.
-(x + 2)(x - 4) = -x² + 2x + 8 so the y-int. is (0, 8). To find the rest we'll complete the square.
-x² + 2x + 8 = -(x² - 2x) + 8 = -(x -1)² + 1 + 8 = -(x - 1)² + 9 so the vertex is (1, 9) and the axis of symmetry is x = 1. This means that the domain is all real numbers and the range is y ≤ 9.
