Question

lesson 4: using function notation to describe rules (part 1)
cool down: perimeter of a square

1. complete the table with the perimeter of a square for each given side length.

side length (inches) perimeter (inches)
0.5
7
20

1. write a rule for a function, p, that gives the perimeter of a square in inches when the side length is $x$ inches.
2. what is the value of $p(9.1)$? what does it tell us about the side length and perimeter of the square?

Explanation:

Step1: Calculate perimeter for 0.5 in

Perimeter = $4 \times 0.5 = 2$

Step2: Calculate perimeter for 7 in

Perimeter = $4 \times 7 = 28$

Step3: Calculate perimeter for 20 in

Perimeter = $4 \times 20 = 80$

Step4: Define perimeter function

Perimeter of square = 4×side length, so $P(x) = 4x$

Step5: Compute $P(9.1)$

$P(9.1) = 4 \times 9.1 = 36.4$

Answer:

1. Completed table:

Side Length (inches)	Perimeter (inches)
7	28
20	80

1. $P(x) = 4x$

1. $P(9.1) = 36.4$. This tells us that a square with a side length of 9.1 inches has a perimeter of 36.4 inches.