Find the vertex of the graph of the equation y = -2x^2+8x-15 + 4x - 8.
This is what the parabola looks like when graphed (sorry for bad image quality), with a vertext at \(\color {red} 3, -5\)
y=-2x^2+12x-23
a=-2 b=12 c=-23
Use formula -b/2a: -12/-4=3
x=3
Plug in 3 as x: y=-2(3)^2+12(3)-23
y=-5
(3,-5)
+2666 
