Chapter 5 Polynomials and Polynomial Functions - 5.9 Write Polynomial Functions and Models - 5.9 Exercises - Skill Practice - Page 397: 11

$f(x)=\dfrac{3}{8}(x+1)(x-2)(x-5)$

We need to plug in $x=1$ and $f(x)=3$ in order to get the correct answer. Here, we have $f(x)=a(x+1)(x-2)(x-5)$ $3=a(1+1)(1-2)(1-5)$ or, $3=8a$ This gives: $a=\dfrac{3}{8}$ Thus, we have $f(x)=\dfrac{3}{8}(x+1)(x-2)(x-5)$