Answer:
D
Explanation:
Given
f(x) = 3x² - 24x + 10 ← factor out 3 from 3x² - 24x
= 3(x² - 8x) + 10
Using the method of completing the square
add/ subtract ( half the coefficient of the x- term )² to x² - 8x
f(x) = 3(x² + 2(- 4)x + 16 - 16) + 10
= 3(x - 4)² - 48 + 10
= 3(x - 4)² - 38 ← in vertex form → D