Proportional Equations and Graphs

constant = k

 $\frac{y}{x}or\ y\div x$  

EXAMPLE: Find the constant rate between time and water used?

Find X and Y.

Find the constant = y /x

If all ratios have the same constant the table is PROPORTIONAL!

Is this table proportional?

Find the constant =

Use the constant to find the missing information

have points that create a straight line

go through the origin (0,0)

Remember constants are like unit rates

Unit rates: a relationship where the second quantity is ONE

Look at the x axis (left to right), and find 1

Then go down to the left of the graph or y axis!

This number is your constant!

use the form y = kx

k is the constant

EXAMPLES:

y = 3x

y= 1/2x

y = 5/3x

y=12x

 $Find\ y\ \div x$  = constant 

Remember the form for equations y = kx

Replace the letter k with your constant 

Example: y = 9x