A parabola has equation y=9x^2 + x +c. One x-intercept is -2. What is the value of c?

Answer 1

c= -34

(x+2)(9x-17) = 9x^2 +x -34

2 x intercepts: -2 and 17/9

divide x+2 into 9x^2 +x +c and make it come out even with no remainder, then c=-34

Answer 2

An x intercept of -2 means that the function crosses the point (-2,0).

So plug that point in and solve for c.

y = 9x² + x + c

0 = 9(-2)² + (-2) + c