Is $\frac{y}{x z} = - 4$ $y/(xz) = -4$ a direct variation, inverse variation, joint or neither?

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Answer 1 · 2015-08-04T19:40:38

This is an example of joint variation.

"Joint variation" means "direct variation, but with two or more variables".

All the variables are directly proportional, taken one at a time.

Your equation is $\frac{y}{x z} = - 4$ $y/(xz) = -4$ .

We can rearrange this to $y = - 4 x z$ $y = -4xz$ .

In words, we would say,

$y$ $y$ varies directly as $x$ $x$ and $z$ $z$ , and the constant of variation is $- 4$ $-4$ .

Is yxz=−4y/(xz) = -4 a direct variation, inverse variation, joint or neither?