find the values of x such that f(x)=0 the function is f(x)=xsquared+3x-18

Question

find the values of x such that f(x)=0 the function is f(x)=xsquared+3x-18

Answer 1

y = x^2 +3x - 18 = 0

(x+6)(x-3) = 0

x =3 or -6

axis of symmetry is half way between (3-6)/2 = -3/2

the polynomial is an upward opening parabola with x intercepts = (3,0) and (-6,0)

vertex = minimum point = (-3/2, -81/4) = (1.5, -20.25)

y= (-3/2)^2 +3(-3/2) - 18 = 9/4 -18/4- 72/4 = -81/4 = -20.25

graph it and the parabola intersects the x axis when x= 3 or x=-6