Question

Write the quadratic function f(x) = 3(x + 1)(x – 7) in standard form.

A)

f(x) = x2 – 18x – 21


B)

f(x) = 3x2 – 18x – 21


C)

f(x) = x2 – 6x – 7


D)

f(x) = 3x2 – 6x – 7

Answer 1

B

Explanation:

Given

f(x) = 3(x + 1)(x - 7) ← expand the factors using FOIL

= 3(x² - 6x - 7) ← distribute the parenthesis

= 3x² - 18x - 21 → B