Question

Given the equation y=-x^2+8x-15 with roots at x=3 and x=5, which statement describes its graph? A. The parabola opens upward and does not intersect the x-axis. B. The parabola opens downward and intersects the x-axis at -3 and -5. C. The parabola opens downward and intersects the x-axis at 3 and 5. D. The parabola opens upward and intersects the x-axis at 3 and 5.

Answer 1

C. The coefficient of x^2 is -1 so the parabola opens downward, and plugging in x = 3 and x = 5 gives y = 0, so it intersects the x-axis at 3 and 5.