Question

Which function models the area of a rectangle with side lengths of 2x – 4 units and x + 1 units? What is the area when x = 3?

A. f(x) = 2x2 – 4x + 4; A = 10 B. f(x) = 2x2 + 8x – 4; A = 38 C. f(x) = 2x2 – 8x + 4; A = 2 D. f(x) = 2x2 − 2x − 4; A = 8

Answer 1

Answer is D. f(x) = 2x^2 -2x -4, A = 8

Step by step

Distribute Multiply (2x -4) (x + 1)

2x^2 + 2x -4x -4
Combine like terms

2x^2 - 2x -4
Substitute value of x =3 into your equation

2 (3^2) - (2)(3) -4

18 - 6 - 4 = 8 units