Question

If f(x) = x2 – 3x – 40 intersects the x-axis at points A and B, what is the sum of A and B?

Answer 1

3

Explanation:

Intersections on the x axis occur when y = 0. f(x) is another term for y, so set f(x) equal to zero and solve for the two possible x's.

0 = x^2 - 3x - 40

0 = (x-8)(x+5)

By solving for x, you get 8 and -5. 8 and -5 added together will equal 3.