Chapter 4 Quadratic Functions and Factoring - 4.10 Write Quadratic Functions and Models - 4.10 Exercises - Skill Practice - Page 312: 10

$y=-3(x-5)^{2}$

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 $a$... $y=a(x-h)^{2}+k$ $-27=a(2-5)^{2}$ $-27=a(-3)^{2}$ $9a=-27$ $a=-\frac{27}{9}$ $a=-3$ Therefore the function is... $y=-3(x-5)^{2}$