The quadratic is in binomial form (factored form), so we will expand it to reveal the coefficients we need for the axis of symmetry formula.
Use the FOIL Method to expand the binomial into a quadratic trinomial:
First Outer: (x•x)+3•x
Simplify: x²+3x
Inner Last: (-6•x)+(-6•3)
Simplify: -6x-18
Expanded Form:
f(x)=x²+3x-6x-18
Combine like terms:
x²-3x-18
Quadratic Standard Form:
f(x)=x²-3x-18
Axis if symmetry formula:
x=-b/2a
Since quadratic standard form is ax²+bx+c=0, in the given function, a=1 and b=-3
Input these values into the formula:
x=-(-3)/2(1)
Simplify:
x=3/2
Thus, the axis of symmetry is x=3/2 or x=1.5