Find the vertex of the graph of the equation y = -2x^2 + 8x - 15 + 6x^2 + 14x + 28.
Simplify as
y = 4x^2 + 22x + 13
x coordinate of the vertex = -22 / (2*4) = -22/8 = -11/4
y coordinate = 4(-11/4)^2 + 22 (-11/4) + 13 = -69/4
+948 
