Direct & Inverse Proportion

When one quantity changes, the other follows — learn when they scale together and when they work against each other.

Direct Proportion

Understand direct proportion — when two quantities increase together at a constant rate — and use the equation y = kx to solve problems.
Inverse Proportion

Learn inverse proportion — when one quantity increases as the other decreases — and use y = k/x to solve any problem.
Proportion with Powers & Roots

Extend proportion to y = kx² and y = k/x² — when the relationship between two quantities involves squaring or square-rooting.