a=6m
b=6n(m,n nguyen to cung nhau)(1)
BCNN(a,b)=m*n*6
a*b=BCNN(a,b)*ƯCLN(a,b)
=> m*n*6*6=864
m*n*36=864
m*n=24(2)
Tu 1 va 2 =>
Ta co
| m | 1 | 24 | 3 | 8 |
| n | 24 | 1 | 8 | 3 |
| a | 6 | 144 | 18 | 48 |
| b | 144 | 6 | 48 | 18 |
a) 3N2O
b)5K2CO3
c)4MgSO4