y=-3x^2+12x-3= -3(x-2)^2 + 9
y=-3x²+12x-12+9 =-3(x²-4x+4)+9 =-3(x-2)²+9
y=-3x^2+12x-3 =-3(x-4x+4)+12-3 =-3(x-2)²+9