Cau tra loi la :
x0x05 Ta co :5+X+X=aa
+ 50x0x 5+X x2=aa
x050x X x2=aa -5
aaaaaa
Vi 1 <x<9 nen 2<aa - 5<18 hay 7<aa<23.
Suy ra a = 1 hoac a = 2.
- Neu a = 1 thi X x2=11-5=6
x=6 : 2 = 3
- Neu a = 2 thi X x2 = 22-5=17 ( khong duoc )
Vay X = 3
Cac ban co the copy de hoc nhe !