Question

How do you graph the function, label the vertex, axis of symmetry, and x-intercepts. `f(x)=x^2-18x+86`?

Answer 1

`f(x) = x^2 - 18x + 86`

Explanation:

`x` of vertex = `x` of symmetry = `x = -b/(2a) = 18/2 = 9`

`y` of vertex: `y = f(9)`= 81 - 162 + 86 = 5

To find x-intercepts, make y = 0

D = `b^2 - 4ac` = 324 - 344 = - 20 < 0.
There are no real roots (x-intercepts). The parabola open upward (a > 0). The parabola is completely above the x-axis.