The area (in square feet) of the school sign can be represented by 15x^2-x-2.

Question

The sign height is (3x+1) ft.

a. Write an expression that represents the length of the sign.

b. Describe two ways to find the area of the sign when x=3.

1. Substitute _ for _ into the expression for the area $15x^2-x-2, then simplify.

2. Substitute _ for _ into the expressions for the length (_) and width (3x+1), simplify each, then multiply these two numbers.

Answer 1

(15x^2 -x -2)/(3x+1) = (5x-2)(3x+1)/(3x+1)= 5x-2 for the width

Area when x=3 is (3x+1)(5x-2) = (9+1)(15-2) = 10(13) = 130 square feet

or plug 3 into 15x^2-x-2 = 15(9)-3-2 = 135-5 = 130 square feet

substitute 3 for x in (3x+1)(5x-2)

or substitute 3 for x in 15x^2-x-2