[(x^2+y^2)- (x-y)^2+2y(x-1)]/4y
=[x^2+y^2- x^2+2xy-y^2+2xy-2y]/4y
=[x^2- x^2+y^2-y^2+2xy+2xy-2y]/4y
=[4xy-2y]/4y
=2y[2x-1]/4y
=(2x-1)/2
经化简代数式与y的取值无关
[(x^2+y^2)- (x-y)^2+2y(x-1)]/4y
=[x^2+y^2- x^2+2xy-y^2+2xy-2y]/4y
=[x^2- x^2+y^2-y^2+2xy+2xy-2y]/4y
=[4xy-2y]/4y
=2y[2x-1]/4y
=(2x-1)/2
经化简代数式与y的取值无关