## Algebra 2 (1st Edition)

$y=-3|x|$.
The functions have the form $y=a|x-b|+c$ where $(b,c)$ is the vertex of the function. Hence, since the vertex is at $(0,0)$, $y=a|x|$. Since $(1,-3)$ is on the function, plugging in the values we get: $-3=a|1||\\-3=a$. Thus $y=-3|x|$.