[tex]\displaystyle \\
-4x^2 + 6x - 8 = 0 \\ \\
\texttt{The equation for the line of symmetry for the graph is: } \\ \\
x = \frac{-b}{2a} = \frac{-6}{-8} = \frac{3}{4} \\ \\
\Longrightarrow~~\texttt{The equation for the line of symmetry is: } \\ \\
\boxed{x= \frac{3}{4} } ~~~~~(\texttt{vertical line})[/tex]
