Choose a value for a that is greater than 5 and less than 15. Evaluate the

perimeter of the pen for that value, using one of the expressions that you
wrote.

3 answers

Let's choose a = 8.

If the length is 2a, then the length would be 2(8) = 16.
If the width is a + 6, then the width would be 8 + 6 = 14.

The perimeter of the pen would be 2(length + width) = 2(16 + 14) = 2(30) = 60 units.
Explain why you used that expression to evaluate the perimeter of the
donkey’s pen.
The expression 2(length + width) is used to evaluate the perimeter of the donkey's pen because the perimeter is defined as the total distance around the boundary of a shape. In this case, the shape is a rectangle (the donkey's pen), so the perimeter is the sum of all four sides of the rectangle.

In the expression 2(length + width), we are doubling the sum of the length and width because a rectangle has two pairs of equal sides. By adding the length and width together, we get the total distance of one pair of opposite sides, and then by doubling that sum, we account for all four sides of the rectangle.

Therefore, by using the expression 2(length + width), we can accurately calculate the perimeter of the donkey's pen.