Question

Write a function rule for the area of a rectangle whose length is 3 inches more than the width. What is the area of the rectangle when its width is 7 inches?

a) A = 7w + 3
b) A = 7w - 3
c) A = 7w + 21
d) A = 7w - 21

Answer 1

The function rule for the area of a rectangle where the length is 3 inches more than the width is A = w × (w + 3). For a width of 7 inches, the area is 70 square inches, which corresponds to the function rule c) A = 7w + 21.

Step-by-step explanation:

To write a function rule for the area of a rectangle where the length is 3 inches more than the width, we use the formula for the area of a rectangle, A = length × width. Let w be the width of the rectangle. Then, the length would be w + 3 inches. Therefore, the function rule for the area in terms of the width is A = w × (w + 3).

When the width is 7 inches, we substitute 7 for w in the function rule, giving us A = 7 × (7 + 3) = 7 × 10 = 70 square inches. This means the area of the rectangle is 70 square inches when the width is 7 inches. The correct answer is c) A = 7w + 21, which represents the area as a function of the width.