smc

Let's imagine this as a quadratic equation. To find the minimum or maximum value, we always need to find the vertex of the quadratic equation. The vertex of the quadratic is $\frac{-b}{2a}$ in $a{x}^2+bx+c=0$. Then to find the output, or the y value of the quadratic, we plug the vertex "x" value back into the equation. In this quadratic, a=1, b=8, and c=0. So the "x" value is $\frac{-b}{2a}\Rightarrow \frac{-8}{2}=-4$. Plugging it back into $x^2+8x$, we get $16-32=-16\Rightarrow$ $\boxed{-16}$