已知x/y=3,求x²+2xy-3y²/x²-2xy+y²

已知x/y=3,求x²+2xy-3y²/x²-2xy+y²
已知x/y=3,求x²+2xy-3y²/x²-2xy+y²

已知x/y=3,求x²+2xy-3y²/x²-2xy+y²
x/y=3,x=3y,代入得
x²+2xy-3y²/x²-2xy+y²
=9y2+6y2-3y2/9y2-6y2+y2
=12y2/4y2
=3

你写错了吧，是不是（x²+2xy-3y²）/（x²-2xy+y²）
=(x+3y)(x-y)/(x-y)^2
=(x+3y)/(x-y)
=(x/y+3)/(x/y-1)
=6/2=3