1. of Tables and Equations
Proportionality
of Tables and Equations
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2. Warm Up
Find four solutions to each equation and graph them. Choose your own values for x.
1). Y = -2x
2). Y = x + 1
3). Y = 3x - 1

3. Warm Up
1). Y = -2x (blue)
2). Y = x + 1 (red)
3). Y = 3x – 1 (yellow)

4. Review
What is a ratio? Give an example.
What is a proportion? Give an example.

5. Determine if the Table is Proportional
Example 1:
A table is proportional if the ratios of y to x are all equal. X Y -2 -4 -1 1 2 4
This table is proportional.
We can’t make a ratio when x is zero, so we will skip it.

6. Determine the Constant of Proportionality
Example 1:
The constant of proportionality is the constant value of the ratio of two proportional quantities y and x. X Y -2 -4 -1 1 2 4

7. Determine if the Equation is Proportional
Equations that are proportional are written y = kx, where k is the constant of proportionality.
Example 1: X Y -2 -4 -1 1 2 4
The equation for this table is Y = 2x.
The constant of proportionality is 2.

8. There is no constant of proportionality.
Example 2: Tell if the table is proportional. If it is proportional, give the constant of proportionality. X Y -2 -1 2 1 4 6
This table is not proportional because the ratios are not equal.
There is no constant of proportionality.

9. y = 2x + 2 Example 2: What is the equation for this table? X Y -2 -1 22 1 4 6
This table is not proportional so the equation is not proportional. Proportional equations are written y=kx.
There is no constant of proportionality.

10. Example 3:
Jackie wants to buy some pencils for school. If each pencil cost 15 cents, how much will she pay for 3, 5, and 10 pencils?
Fill in the table for the problem.
What is the equation?
Is this proportional? If it is give the constant of proportionality.
Pencil
Price 3 5 10
$0.45
Y=0.15x
$0.75
$1.50
Proportional, COP=0.15

11. Y=2x-4 Y = 2x Y=x+3 Y= -3x Y=2x+12 Y= 1/2x Y= -12+x Y= x-4 Practice
Determine if the equations are proportional.
Y=2x-4
Y=x+3
Y=2x+12
Y= -12+x
Y= x-4
Y = 2x
Y= -3x
Y= 1/2x

12. Practice
Write the equation for each table. Determine if the table is proportional and give the constant of proportionality.
Y = 3x, proportional, constant of prop. Is 3.
Y= 3x+1, not prop.
Y = x + 9, not prop.

13. Practice
4). Allie can run 3 miles in one hour. How many miles can she run in 2, 4 and 6 hours?
What is the equation?
Tell if the table is proportional and give the
constant of proportionality.
Hours
Miles 2 4 6
Y = 3x 6 12 18
It is proportional, the COP is 3

14. Closure What do the equations of proportional tables look like?
What do the equations of non-proportional tables look like?