1.（x²-2x+1-y²)/(x+y-1)=2.a²+2ab+b²+(a-2)²=0,则b=( )

1.（x²-2x+1-y²)/(x+y-1)=2.a²+2ab+b²+(a-2)²=0,则b=( )
1.（x²-2x+1-y²)/(x+y-1)=
2.a²+2ab+b²+(a-2)²=0,则b=( )

1.（x²-2x+1-y²)/(x+y-1)=2.a²+2ab+b²+(a-2)²=0,则b=( )
1.（x²-2x+1-y²)/(x+y-1)
=[(x-1)²-y²]/(x+y-1)
=(x+y-1)(x-y-1)/(x+y-1)
=x-y-1
2.a²+2ab+b²+(a-2)²=0
(a+b)²+(a-2)²=0
平方大于等于0,相加等于0
若有一个大于0,则另一个小于0,不成立.
所以两个都等于0
所以a+b=0,a-2=0
a=2
所以b=-a=-2