已知x²-4xy+4y²=0,且xy≠0,那么x-y/x+y

已知x²-4xy+4y²=0,且xy≠0,那么x-y/x+y
已知x²-4xy+4y²=0,且xy≠0,那么x-y/x+y

已知x²-4xy+4y²=0,且xy≠0,那么x-y/x+y
x²-4xy+4y²=0
(x-2y)²=0
则x=2y ,因为xy≠0,则x≠0且y≠=0
那么 (x-y)/(x+y)
=(2y-y)/(2y+y)
=y/(3y)
=1/3