Question:
What is the maximum value of $4(x + 7)(2 - x)$, over all real numbers $x$?

Answer:
The graph of $y = 4(x + 7)(2 - x)$ is a parabola.  Since $y = 0$ when $x = -7$ and $x = 2$, the $x$-intercepts of the parabola are $(-7,0)$ and $(2,0)$.  If the vertex of the parabola is $(h,k)$, then the $x$-intercepts $(-7,0)$ and $(2,0)$ are symmetric around the line $x = h$, so $h = (-7 + 2)/2 = -5/2$.

Hence, the maximum value of $y = 4(x + 7)(2 - x)$ occurs at $x = -5/2$, in which case \[y = 4 \left( -\frac{5}{2} + 7 \right) \left( 2 + \frac{5}{2} \right) = 4 \cdot \frac{9}{2} \cdot \frac{9}{2} = \boxed{81}.\] (Note that this is a maximum value, and not a minimum value, because the coefficient of $x^2$ in $y = 4(x + 7)(2 - x) = -4x^2 - 20x + 56$ is negative.)