Question

Consider the quadratic function:

f(x) = x2 – 8x – 9



Vertex: (StartFraction negative b Over 2 a EndFraction, f (StartFraction negative b Over 2 a))

What is the vertex of the function?

THE ANSWER IS ( ⇒ 4, ⇒ -25) ON EDGE

Answer 1

Answer:

vertex = (4, - 16 )

Step-by-step explanation:

Given a quadratic in standard form, f(x) = ax² + bx + c : a ≠ 0

Then the x- coordinate of the vertex is

$x_{vertex}$ = - $\frac{b}{2a}$

f(x) = x² - 8x - 9 ← is in standard form

with a = 1, b = - 8, thus

$x_{vertex}$ = - $\frac{-8}{2}$ = 4

Substitute x = 4 into f(x) for corresponding y- coordinate

f(4) = 4² - 8(4) - 9 = 16 - 32 - 9 = - 16

vertex = (4, - 16 )