Question

Find the x-intercepts for the parabola defined by the equation below. y = 3x2 + 18x + 15

Answer 1

Using quadratic formula
x = [-18 +-sq root (324 -4 *3*15)] / 2*3
x = [-18 +-sq root (144)]/6
x1 = (-18 + 12) / 6 = -1
x2 = (-18 -12) / 6 = -30/6 = -5