[tex]\bf \textit{vertex of a vertical parabola, using coefficients}
\\\\
\begin{array}{llcccl}
y = & 1x^2& +16x& +71\\
&\uparrow &\uparrow &\uparrow \\
&a&b&c
\end{array}
\qquad
\left(-\cfrac{ b}{2 a}\quad ,\quad c-\cfrac{ b^2}{4 a}\right)
\\\\\\
\left( -\cfrac{16}{2(1)}~~,~~71-\cfrac{16^2}{4(1)} \right)\implies (-8~~,~~71-64)\implies (-8~,~7)[/tex]
