3m(x-3)=4m(1-x)-1
3mx-9m=4m-4mx-1
7mx=13m-1
x=(13m-1)/7m
因为解是正整数
即
(13m-1)/7m>0
m(13m-1)>0
m>1/13或m<0
(13m)/7m-1/(7m)
=13/7 -1/(7m)
=1+6/7-1/(7m)
因为m是整数,所以
m=-1
3m(x-3)=4m(1-x)-1
7mx=13m-1
x=(13m-1)/7m,x为正整数,因此(13m-1)/m必为正整数且为7的倍数,即13-1/m为正整数且为7的倍数,m是1的因数且为整数,m=±1,代入得出m=-1时满足7的倍数