你好1/(x+5)-1/(x+6)=1/(x+7)+1/(x+8)1/(x+5)-1/(x+7)=1/(x+8)-1/(x+6)2/(x+5)(x+7)=2/(x+8)(x+6)(x+5)(x+7)=(x+8)(x+6)x²+12x+35=x²+14x+48-2x=13x=-13/2【数学辅导团】为您解答,不理解请追问,理解请及时选为满意回答!(*^__^*)谢谢!