很明显(x+2/x+1)=1+(1/x+1),同理原式可化简为(1/x+1)-(1/x+3)=(1/x+5)-(1/x+7)通分化简得x²+4x+3=x²+12x+35,可得x=﹣8
1/(x+1)(x+3)=2/(x+5)(x+7)
x^2+4x+3=x^2+12x+35
x=-8
解: 1+1/x+1-1-1/x-3=1+1/x+5-1- 1/x+7
1/x+1-1/x+3-1/x+5+1/x+7=0
( x+3-x-1)/(x+1)(x+3)=(x+7-x-5)/(x+5)(x+7)
( x+1)(x+3)=(x+5)(x+7)
x^2+4x+3=x^2+12x+35
8x=-32
x=-4