计算 x\x+y-2xy/y^2-x^2
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计算x\x+y-2xy/y^2-x^2计算x\x+y-2xy/y^2-x^2计算x\x+y-2xy/y^2-x^2x\x+y-2xy/y^2-x^2=x\x+y+2xy/(x+y)(x-y)=【x
计算 x\x+y-2xy/y^2-x^2
计算 x\x+y-2xy/y^2-x^2
计算 x\x+y-2xy/y^2-x^2
x\x+y-2xy/y^2-x^2
=x\x+y+2xy/(x+y)(x-y)
=【x²-xy+2xy】/(x+y)(x-y)
=(x²+xy)/(x+y)(x-y)
=x/(x-y)
问题是:X/(X+Y)-2XY/(Y^2-X^2)?
那应该用平方差公式。Y^2-X^2=(Y+X)(Y-X)
X/(X+Y)通分:(XY-X^2)/(Y+X)(Y-X)
那么分母相同,加起来再约分得:
原式=X/(X-Y)
不清楚可以再问
x\x+y-2xy/y^2-x^2
=x\x+y+2xy/(x+y)(x-y)
=【x²-xy+2xy】/(x+y)(x-y)
=(x²+xy)/(x+y)(x-y)
=x/(x-y)