-2/3-m=1-m/3-m
-2(3+m)/(3-m)(3+m)=(1-m)(3+m)/(3-m)(3+m)
-2(3+m)=(1-m)(3+m)
m^2-9=0
(m+3)(m-3)=0
m1=-3,m2=3（舍去）