Question

A word for the relation between x and y in the equation y = k x is ___ variation.

Answer 1

For this case we have to define "y" directly with "x" when there is a constant of proportionality "k", such that:

$y = kx$

This is known as direct variation.

On the other hand, if y varies inversely with x we have to:

$y = \frac {k} {x}$

This is known as inverse variation.

Answer:

$y = kx$, direct variation