x/(x-3)-2=k/(x-3)
x/(x-3)-k/(x-3)=2
(x-k)/(x-3)=2
x-k=2x-6
2x-x=6-k
x=6-k
原式子的增根是:x-3=0,即 x=3.代入(x=6-k)
3=6-k
k=3