x-y分之x+y减x+y分之x-y将其进行通分则得［（x＋y）²－（x－y）²］/x²-y²＝4xy/x²-y²x²分之1减y²分之1将其进行通分则得（y²－x²）/x²y²所以(x-y分之x+...