## Precalculus (6th Edition) Blitzer

$y=kx$ Increasing the value of any one quantity results in increasing the value of the other quantity.
Decreasing the value of any one quantity results in decreasing the value of the other quantity. $y\propto x$ implies that when the variable x increases, y also increases or when x decreases, y also decreases. In order to remove the proportionality sign, use the constant of proportionality k. $y=kx$