解：选A X²-2X-5=0X²-2X+1-6=0(X-1)²-6=0(X-1)²=6
原方程应变形为: (x-1)^2=6
X²-2X+1-1-5=0(X-1)²=6
x^2-2x-5=x^2-2x+1-1-5=(x-1)^2-6=0(x-1)^2=6
X平方-2X-5=x�0�5-2x+1-1-5=(x-1)�0�5-6答案B谢谢采纳
