1/(x-86) - 1/(x-87) = 1/(x-89) - 1/(x-90)
令t=x-88
原方程化為：
1/(t+2)-1/(t+1)=1/(t-1)-1/(t-2)
(t+1-t-2)/[(t+2)(t+1)] = (t-2-t+1)/[(t-1)(t-2)]
-1/[(t+2)(t+1)] = -1/[(t-1)(t-2)]
(t+2)(t+1) = (t-1)(t-2)
t^2+3t+2=t^2-3t+2
3t=-3t
t=0
t=x-88=0
x=88 ,經(jīng)檢驗不是增根好復(fù)雜，能容易點嗎？中間步驟可以略，因為怕你看不懂才寫的想這么復(fù)雜。