( - 6, 0).(2, 0 ) , vertex = ( - 2, - 16)
to find the x-intercepts set f(x) = 0
x² + 4x - 12 = 0
(x + 6)(x - 2) = 0 ( equate each factor to zero and solve for x )
x + 6 = 0 ⇒ x = - 6
x - 2 = 0 ⇒ x = 2
x- intercepts are ( - 6, 0),(2, 0)
given the quadratic in standard form : y = ax² + bx + c
the x-coordinate of the vertex = -
here a = 1 , b = 4 and c = - 12
x- coordinate of vertex = - = - 2
substitute this value into the equation for y-coordinate
x = - 2 → y = 4 - 8 - 12 = - 16
vertex = ( - 2, - 16)