答：
方程x/(x-1)=m+2m/(1-x)有增根
x/(x-1)=m*[(x-1-2)/(x-1)]
x/(x-1)=m*(x-3)/(x-1)
x=mx-3m
(m-1)x=3m
增跟x=1,代入得：
m-1=3m
2m=-1
m=-1/2