8
QuizMultiple Choice

Adding and Subtracting Polynomials

Question 8 • Common Core Algebra I B-IC

Margot is sewing a ribbon on a seam along the perimeter of a square pillow. The side length of the pillow is 2x2+1 inches. She plans to make a similar pillow, including the ribbon, whose side length is 4x−7 inches. What expression can be used for the length of ribbon that she needs for both pillows, and what is the length if x = 3.5?

Answer
A
2x2+4x−6; 22.0 inches
B
2x2+4x−6; 32.5 inches
C
4(2x2+4x−6;) 88.0 inches
D
4(2x2+4x−6;) 130.0 inches

Explanation

A square’s perimeter is 4 times its side length. Adding the side lengths of the two pillows gives (2x² + 1) + (4x − 7) = 2x² + 4x − 6, so the total ribbon length is 4(2x² + 4x − 6). When x = 3.5, the expression inside the parentheses is 2(3.5²) + 4(3.5) − 6 = 32.5, and 4 × 32.5 = 130 inches. Thus, the correct choice is D, 4(2x² + 4x − 6), or 130.0 inches.

AI-written and checked against the verified answer.

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