[tex]\bf \textit{vertex of a vertical parabola, using coefficients}
\\\\
\begin{array}{llcccl}
\stackrel{f(x)}{y} = & 1x^2& +4x& -12\\
&\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{4}{2(1)}~~,~~-12-\cfrac{4^2}{4(1)} \right)\implies (-2~~,~~-12-4)\implies (-2~~,~~-16)[/tex]
