Question

can someone explain how to find the answer please?

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

x = −3

x = 3

x = −6

x = 6

Answer 1

find the vertex of \(f(x) = −3x^2 + 18x − 7 \) or just compute \(-\frac{b}{2a}\) with \(a=-3,b=18\)

Answer 2

axis of symmetry for
\[y=ax^2+bx+c\] is
\[x=-\frac{b}{2a}\]

Answer 3

so all i do is plug in the points, (-3,18), and solve?

Answer 4

not sure what you mean, it is not a point, it is a number

Answer 5

i.e. \[-\frac{b}{2a}=-\frac{18}{2\times (-3)}\] is what you need to compute for the axis of symmetry

Answer 6

the axis of symmetry is a vertical line
the equation for a vertical line looks like \(x=number\)
in your case the number is \(3\) so the axis of symmetry is \(x=3\)

Answer 7

okay thank you so much!

Answer 8

yw