Constant of Variation
The constant of variation in a direct variation is the constant (unchanged) ratio of two variable quantities.
The formula for direct variation is
(or )
where is the constant of variation .
Example 1:
If varies directly as and when , find when .
Find the constant of variation.
To find , substitute for .
The constant of variation in an indirect variation is the constant (unchanged) product between two variable quantities.
The formula for indirect variation is
(or )
where is the constant of variation .
Example 2:
If it takes hours at an average speed of km/h to do a certain journey, how long would it take at km/h?
Find the constant of variation.
= speed · time
Then,