Chapter 4 Quadratic Functions and Factoring - 4.10 Write Quadratic Functions and Models - 4.10 Exercises - Skill Practice - Page 312: 13

$y=\frac{1}{3}(x+1)^{2}-4$

We already know $y$, $x$, $k$ and $h$ from the given vertex and point, so in order to get the quadratic function we need to find $a$... $y=a(x-h)^{2}+k$ $-1=a(2+1)^{2}-4$ $+3=a(3)^{2}$ $9a=3$ $a=\frac{3}{9}$ $a=\frac{1}{3}$ Therefore the function is... $y=\frac{1}{3}(x+1)^{2}-4$