已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
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已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值
x/y=3
x=3y
x²+2xy-3y²/x²-xy+y²
= { (3y)^2+2*3y*y-3y^2} / { (3y)^2-3y*y+y^2 }
= 12y^2 / (7y^2)
=12/7