Example 1

A super bouncy ball will rebound half of the distance from which it is dropped on each bounce. If it is dropped from a height of 72 inches, how many rebounds will it make? Is this a linear relationship?

Column 1: 0 – 4, column 2: 72, 36, 18, 9, 4.5

The y values in the table are decreasing by different heights on each row, and the x values are increasing by one rebound. Since the changes in the y values are not constant, this function is not linear.


Example 2

mower

Source: Old Mower, Cavalier92, Flickr

Pedro mows lawns on Saturday to earn extra money. He charges $40 for each lawn he mows. Every Saturday, Pedro must buy gasoline for his lawn mower and plastic bags for the cut grass. His expenses are $32 each Saturday.

Create a table to see if this problem situation has a constant rate of change. Click on the blanks to check your answers.

Number of Lawns Pedro's Profit
0
-32
1
8
2
____
3
____

 

Before Pedro mows any lawns, he pays $32. Since this is an expense, it is represented as a negative number.

If Pedro mows one yard, his profit will be $8.

If Pedro mows two yards, his profit will be ____ .

If Pedro mows three yards, his profit will be ____ .

What is the change in the x values?

What is the change in the y values?

What is the slope?

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Check Your Answer

Change in x: 1
Change in y: 40
Slope: 40 Close Pop Up

If y represents Pedro's profit and x represents the number of lawns, what equation represents this relationship?

Is this a linear function, why?

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Check Your Answer

y = 40(x) – 32
Yes, this is a linear function because there is a constant rate of change or slope of 40. Close Pop Up