## Algebra 2 Common Core

The origin can be used to test whether a linear equation is a direct variation function because if it is plugged into a linear equation and the equation becomes $0=0$, it is a direct variation.
A direct variation: $y=\frac{7}{3}x$ $0=\frac{7}{3}(0)$ $0=0$ Not a direct variation: $y=8x+6$ $0=8(0)+6$ $0=6$