check the picture below.
[tex]\bf \textit{ vertex of a vertical parabola, using coefficients}\\\\
\begin{array}{lccclll}
y = &{{ -16}}x^2&{{ +32}}x&{{ +0}}\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}\qquad
\left(-\cfrac{{{ b}}}{2{{ a}}}\quad ,\quad {{ c}}-\cfrac{{{ b}}^2}{4{{ a}}}\right)[/tex]
so, the object reaches at maximum height of [tex]\bf {{ c}}-\cfrac{{{ b}}^2}{4{{ a}}}\ feet[/tex]
