Answer
One of the answers is
$y=x^3-7x^2-20x+96$
Work Step by Step
The easiest way to build such an equation is to look for it in the form of a polynomial of the third degree with three real zeros $x_1 = -4, x_2=3$ and $x_3=8$. According to a theorem in algebra of polynomials, such a polynomial is of the form of
$$y=a(x-x_1)(x-x_2)(x-x_3)$$
where $a$ is any nonzero real. Here we need only one solution so for simplicity just put $a=1$:
$$y=(x+4)(x-3)(x-8)$$
or expanded
$$y=x^3-7x^2-20x+96.$$
