Y=-2(x-4)^2-6
The -6 makes it shift from origin(0,0) to (0,-6)
Then the -4 inside with x, makes it shift to the right by for, so the center would be now instead of (0,0), (4,-6).
As it has a negative A factor, it is a parabola open downwards, so the center is the maximum value.
Answer: (4,-6)
Hope you get it!