y=1/2*(x^2-4x)+1=1/2*(x-2)^2+1-2=1/2*(x-2)^2-1A~D都不对呀。前面的a至少得是1/2
y=1/2x^2-2x+1=1/2(x^2-4x)+1=1/2(x^2-4x+4)-1/2×4+1=1/2(x-2)²-1答案没有去 亲
y=1/2x^2-2x+1 =1/2(x^2-4x)+1=1/2(x^2-4x+4)-1/2×4+1=1/2(x-2)²-1
y=1/2x^2-2x+1=1/2(x-2)^2-1