x^2-4y^2/x^2+4xy+4y^2-x/x+2y,其中x=-4,y=-3x^2-4y^2/(x^2+4xy+4y^2)-x/(x+2y),其中x=-4,y=-3

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x^2-4y^2/x^2+4xy+4y^2-x/x+2y,其中x=-4,y=-3x^2-4y^2/(x^2+4xy+4y^2)-x/(x+2y),其中x=-4,y=-3
x^2-4y^2/x^2+4xy+4y^2-x/x+2y,其中x=-4,y=-3
x^2-4y^2/(x^2+4xy+4y^2)-x/(x+2y),其中x=-4,y=-3

x^2-4y^2/x^2+4xy+4y^2-x/x+2y,其中x=-4,y=-3x^2-4y^2/(x^2+4xy+4y^2)-x/(x+2y),其中x=-4,y=-3
(x^2-4y^2)/(x^2+4xy+4y^2)-x/(x+2y)
=[(x+2y)(x-2y)]/(x+2y)^2-x/(x+2y)
=(x-2y)/(x+2y)-x/(x+2y)
=-2y/(x+2y)
=6/-10
=-3/5