x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值.

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x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值.x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先

x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值.
x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值.

x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2.其中x=2,y=-1.先化简再求值.
x^2-y分之y(x-y)-x(x+y)除以x+y分之x^2+y^2
=[(-x^2-y^2)/(x^2-y)]÷[(x^2+y^2)/(x+y)]
=(x+y)/(y-x^2)
=(2-1)/(-1-2^2)
=-1/5
如果此题是
x^2-y^2分之y(x-y)-x(x+y)除以x+y分之x^2+y^2
=[(-x^2-y^2)/(x^2-y^2)]÷[(x^2+y^2)/(x+y)]
=(x+y)/(y^2-x^2)
=1/(y-x)
=1/(-1-2)
=-1/3
你能明白,赞同

楼主,你描述清楚点,y分之y(x-y)-x(x+y)是[y(x-y)-x(x+y)]/y还是单个的除以y,然后后面又是除以x+y分之x^2+y^2,到底哪些是分子,哪些是分母啊,要不就弄个图片上来。

x^2-(y(x-y)-x(x+y))/y÷(x^2+y^2)/(x+y)
=x^2+(x^2+y^2)/y÷(x^2+y^2)/(x+y)
=x^2+x/y+1
代入数据
=2×2-2+1
=3

=x^2-Y/-(Y^2+X^2)除以(X+Y)/X^2+Y^2
=(Y-X^2)/(X+Y)
= -5