parabola terbuka ke kiri

\begin{tikzpicture}[scale=.15]
\draw[Crimson, line width=1.25pt, domain=-20:24] plot[smooth]({-\x*\x/16 +1/4*\x+7/4},\x) node[above] {$y^2-4y+16x-28=0$};
\draw[densely dashed,help lines] (-50,2)--(10,2) node[midway,above left,xshift=-2cm,SeaGreen] {sumbu simetri};
\draw[bistres,-stealth,line width=1pt] (-50,0)--(10,0);
\draw[bistres,-stealth,line width=1pt] (0,-25)--(0,25);
\draw[SeaGreen,fill=Yellow] (2,2) circle (10pt) node[above right]{titik puncak} (-2,2) circle (10pt) node[above left]{titik fokus};
\end{tikzpicture}