Question

What is the axis of symmetry for f(x) = -3x2 + 18 - 7

Answer 1

The vertex form:

`y=a(x-h)^2+k\\\\(h,\ k)-vertex`

The axis of symetry is x = h.

`y=ax^2+bx+c\to h=(-b)/(2a)`

We have

`f(x)=-3x^2+18x-7\to a=-3,\ b=18,\ c=-7`

Substitute:

`h=(-18)/((2)(-3))=(-18)/(-6)=3`

Answer: x = 3