Chapter 4 Quadratic Functions and Factoring - 4.10 Write Quadratic Functions and Models - 4.10 Exercises - Skill Practice - Page 313: 22

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

We already know $y$, $x$, $p$ and $q$ from the given x-intercepts and the point, so in order to get the quadratic function we need to find $a$... $y=a(x-p)(x-q)$ $4=a(2+1)(2-4)$ $4=-6a$ $a=-\frac{4}{6}$ $a=-\frac{2}{3}$ Therefore the function is... $y=-\frac{2}{3}(x+1)(x-4)$