3ax+2by=5c
3a'+2b'y=5c'两个式子都除以5
得3/5ax+2/5by=c
3/5a'x+2/5b'y=c'
把x=3
y=4分别带入原方程组
3/5xa+2/5yb=c
3a +4b=c
3/5ya'+2/5yb'=c'
3a' +4b'=c’
因为结果相同,字母相同,所以系数相同.
3/5x=3 x=52/5y=4 y=10