[tex]\bf ~~~~~~\textit{parabola vertex form}
\\\\
\begin{array}{llll}
\boxed{y=a(x- h)^2+ k}\\\\
x=a(y- k)^2+ h
\end{array}
\qquad\qquad
vertex~~(\stackrel{}{ h},\stackrel{}{ k})\\\\
-------------------------------\\\\
\begin{cases}
h=2\\
k=6
\end{cases}\implies y=a(x-2)^2+6
\\\\\\
\textit{we also know that }
\begin{cases}
x=1\\
y=8
\end{cases}\implies 8=a(1-2)^2+6\implies 2=a(-1)^2
\\\\\\
2=a\qquad therefore\qquad y=2(x-2)^2+6[/tex]
