Question 1025189
Expect an equation {{{y=-2(x-(3+sqrt(5)))(x-(3-sqrt(5)))}}}, 
...
and simplify it.  A few steps and take advantage of Difference of Squares,...
{{{y=-2(x^2-6x+4)}}}----not yet in "general form", but as this, easier to see how to Complete the Square for putting into Standard Form.


Without trying to explain, ADD and SUBTRACT 9 inside the parenthesized expression.
{{{-2(x^2-6x+9-9+4)}}}
{{{-2((x-3)^2-5)}}}
{{{highlight(y=-2(x-3)^2+10)}}}


Read the vertex directly from the standard form equation.
VERTEX:   (3,10)