Select the correct answer.

Sam is installing a walkway around a rectangular flower patch in his garden. The flower patch is 12 feet long and 6 feet wide. The width of the walkway is [tex]x[/tex] feet.

Sam created the function [tex]A(x)[/tex] to represent the total area taken up by the flower patch and walkway by multiplying the functions modeling the new total length and width.
[tex]\[A(x) = 4x^2 + 36x + 72\][/tex]

What does [tex]4x^2 + 36x[/tex] represent in this function?

A. the area of the walkway along the width of the flower patch
B. the area of the walkway along the length of the flower patch
C. the total area of the walkway
D. the total area of the flower patch



Answer :

Let's analyze Sam's situation step by step:

1. Dimensions of the Flower Patch:
- The flower patch is 12 feet long and 6 feet wide.

2. Area of the Flower Patch:
- The area of the flower patch is calculated by multiplying its length and its width:
[tex]\[ \text{Area of flower patch} = 12 \times 6 = 72 \text{ square feet}. \][/tex]

3. Function [tex]\(A(x)\)[/tex]:
- Sam created the function [tex]\(A(x)\)[/tex] to represent the total area taken up by the flower patch and the walkway:
[tex]\[ A(x) = 4x^2 + 36x + 72. \][/tex]

4. Interpreting [tex]\(A(x)\)[/tex]:
- The function [tex]\(A(x)\)[/tex] can be compared to the expansion of the product [tex]\((\text{new length}) \times (\text{new width})\)[/tex]:
- The new length of the flower patch plus the walkway is [tex]\((12 + 2x)\)[/tex].
- The new width of the flower patch plus the walkway is [tex]\((6 + 2x)\)[/tex].

Expanding [tex]\((12 + 2x)(6 + 2x)\)[/tex]:
[tex]\[ (12 + 2x)(6 + 2x) = 12 \times 6 + 12 \times 2x + 2x \times 6 + 2x \times 2x = 72 + 24x + 12x + 4x^2 = 4x^2 + 36x + 72. \][/tex]

5. Identifying Components in [tex]\(A(x)\)[/tex]:
- In the function [tex]\(A(x) = 4x^2 + 36x + 72\)[/tex]:
- The term [tex]\(72\)[/tex] represents the original area of the flower patch.
- The terms [tex]\(4x^2 + 36x\)[/tex] represent the additional area added by the walkway.

6. Conclusion:
- The combined terms [tex]\(4x^2 + 36x\)[/tex] specifically represent the area added by the walkway.

Therefore, the correct answer is:

C. the total area of the walkway