1/(x-3)+1/(x-7)=1/(x-4)+1/(x-6).
1/(x-3)-1/(x-4)=1/(x-6)-1/(x-7)
(x-4-x+3)/(x-3)(x-4)=(x-7-x+6)/(x-6)(x-7)
-1/(x-3)(x-4)=-1/(x-6)(x-7)
(x-6)(x-7)=(x-3)(x-4)
x²-13x+42=x²-7x+12
-6x=-30
x=5
检验：x=5是方程的根