Question

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

Answer 1

The axis of symmetry of a parabola like

`y=ax^2+bx+c`

is a vertical line of the form

`x = k`

where k is the x coordinate of the vertex of the parabola.

In particular, the x coordinate of the vertex of the parabola is given by

`x = -(b)/(2a)`

which in your case becomes

`x = -(18)/(-6) = 3`

So, the axis of symmetry is the line

`x=3`