Question

先化简,再求值,[x²+y²-(x-y)²+2y(x-y)]÷4y.其中x,y满足x

Answer 1

[x²+y²-(x-y)²+2y(x-y)]÷4y

=[x²+y²-(x²-2xy+y²)+2y(x-y)]÷4y

=(x²+y²-x²+2xy-y²+2xy-2y²)÷4y

=(4xy-2y²)÷4y

化简得=（2x-y）÷2

x²-2x+1+|y+1|=0

(x-1)²+|y+1|=0

(x-1)²=0 |y+1|=0

x=1 y= -1

所以（2x-y）÷2=3/2