(x+1+1)/(x+1)+(x+7+1)/(x+7)=(x+5+1)/(x+5)+(x+3+1)/(x+3)
1+1/(x+1)+1+1/(x+7)=1+1/(x+5)+1+1/(x+3)
1/(x+1)+1/(x+7)=1/(x+5)+1/(x+3)
通分
(2x+8)/(x²+8x+7)=(2x+8)/(x²+8x+15)
(2x+8)[1/(x²+8x+7)-1/(x²+8x+15)]=0
x²+8x+7≠x²+8x+15
所以1/(x²+8x+7)-1/(x²+8x+15)≠0
所以2x+8=0
x=-4
分式方程要检验
经检验,x=-4是方程的解