Question 1018253
{{{y=2x^2-4x-2}}}  is not factorable.  You can change into standard form and read the vertex and also find the zeros (or x-axis intercepts) by equating y=0.


{{{graph(300,300,-6,6,-6,6,2x^2-4x-2)}}}


Also you could just use the general solution formula for a quadratic equation.

{{{2(x^2-2x-1)=0}}}
{{{x^2-2x-1=0}}}
{{{x=(2+- sqrt((-4)^2-4*(-1)))/2}}}
{{{x=(2+- sqrt(20))/2}}}
{{{x=(2+- 2sqrt(5))/2}}}
{{{highlight(x=1+- sqrt(5))}}}-------the x-axis intercepts, therefore the vertex and symmetry axis are quickly and easily found.