抛物线
y=2x^2-12x+16
=2(x^2-6x+8)
=2(x^2-6x+9-1)
=2(x-3)^2-2
所以
抛物线为:
y=-2(x-3)^2-2
=-2(x^2-6x+9)-2
=-2x^2+12x-20