原式=[(x-y+z)(x+y-z)]/[(x+y-z)(x+y+z)] 注：根據(jù)a²-b²=（a-b）（a+b）
=（x-y+z)/(x+y+z)具體步驟。。請清楚點。。我覺得已經(jīng)很具體了啊………………x²-(y-z)²/(x+y)²-z² =[x-(y-z)][x+(y-z)]/[(x+y)-z][(x+y)+z]拆開…………=[(x-y+z)(x+y-z)]/[(x+y-z)(x+y+z)] 消去(x+y-z)這項……=（x-y+z)/(x+y+z) 夠具體了吧TAT