Question

A quadratic function is defined by \small f\left(x\right)=x^2-8x-4. Which expression also defines \small f and best reveals the maximum or minimum of the function?

Answer 1

Answer:

f(x) = [x – (4 + √20)][x – (4 – √20]

Step-by-step explanation:

In order to know the function that best describes the given f(x) that best reveals it's minimum or maximum, we need to know solve for x.

x² – 8x – 4 = 0

Using completing the square method

x² – 8x = 4

x² – 8x + 4² = 4 + 4²

(x – 4)² = 20

x = 4 ±√20

Therefore

f(x) = [x – (4 + √20)][x – (4 – √20]