原式毁梁=1/(x-1)(x+1) + (x+1+x+5)/(x+1)(x+3)(x+5)=1/(x-1)(x+1) +2(x+3)/(x+1)(x+3)(x+5)=1/(x-1)(x+1) + 2/纤悉运(x+1)(x+5)=[x+5+2(x-1)]/(x+1)(x-1)(x+5)=[3(x+1)]/陆册(x+1)(x-1)(x+5)=3/(x-1)(x+5)