Annalise makes rectangular patchwork quilts out of leftover fabric scraps. The first scrap she is using to make a quilt has a width of 2x feet and a length of 5x feet. When finished, the entire quilt will be 5 feet wider and 3 feet longer than the first fabric scrap used. Which of the following functions will give the area, f(x), of the quilt in square feet?

A.
f(x) = 10x2 + 16x + 15
B.
f(x) = 10x2 + 15
C.
f(x) = 10x2 + 31x + 15
D.
f(x) = 10x2 + 25x + 15

1 answer

To determine the area of the entire quilt as a function of \( x \), we will first find the dimensions of the quilt based on the given information about the first fabric scrap.

  1. The width of the first scrap is \( 2x \) feet.
  2. The length of the first scrap is \( 5x \) feet.

Now, we need to calculate the dimensions of the entire quilt. According to the problem:

  • The quilt will be 5 feet wider than the first fabric scrap, so the width of the quilt is: \[ \text{Width of quilt} = 2x + 5 \]

  • The quilt will be 3 feet longer than the first fabric scrap, so the length of the quilt is: \[ \text{Length of quilt} = 5x + 3 \]

Next, we can calculate the area of the quilt by multiplying its width and length: \[ \text{Area of quilt} = (\text{Width of quilt}) \times (\text{Length of quilt}) = (2x + 5)(5x + 3) \]

Now, we will expand this expression: \[ (2x + 5)(5x + 3) = 2x(5x) + 2x(3) + 5(5x) + 5(3) \] \[ = 10x^2 + 6x + 25x + 15 \] \[ = 10x^2 + 31x + 15 \]

Thus, the function \( f(x) \) that represents the area of the quilt in square feet is: \[ f(x) = 10x^2 + 31x + 15 \]

The correct answer is: C. \( f(x) = 10x^2 + 31x + 15 \)