①x²-6x+11=(x-3)²-9+11=(x-3)²+2
②3x²-6x-2=3(x-1)²-3-2=3(x-1)²-5
③-2x²-3x+1=-2(x+3/4)²+9/2+1=-2(x+3/4)²+11/2
④-2x²+5x-7=-2(x-5/4)²+25/2-7=-2(x-5/4)²+11/2
①x²-6x+11=(x-3)²-9+11=(x-3)²+2
②3x²-6x-2=3(x-1)²-3-2=3(x-1)²-5
③-2x²-3x+1=-2(x+3/4)²+9/2+1=-2(x+3/4)²+11/2
④-2x²+5x-7=-2(x-5/4)²+25/2-7=-2(x-5/4)²+11/2