错了,第一个是x²+3原式=(x²+3)/(x+1)(x-1)-(x+1)²/(x+1)(x-1)+(x+1)(x-1)/(x+1)(x-1)=(x²+3-x²-2x-1+x²-1)/(x+1)(x-1)=(x²-2x+1)/(x+1)(x-1)=(x--1)²/(x+1)(x-1)=(x-1)/(x+...