# Is c = 3v a direct variation, inverse variation, or neither?

Jun 11, 2015

$c = 3 v$ is a direct variation.

#### Explanation:

In a direct variation, one number changes based on how the other changes. Basically, some number $x$ will always be a certain number $k$ times more than its partner $y$. This is usually written as:

$y = k x$

In an inverse variation, two numbers change so that their product will stay constant. Unlike a direct variation, one number gets bigger while the other gets smaller. This is usually written as:

$y x = k$

Now look at the original equation: $c = 3 v$
We can see that $v$ will always change relative to $c$, by a factor of 3.
This is also an equation of the form $y = k x$ where $k$ is a constant.
So, this is a direct variation.