Ta có: a+b+b+c+c+a=11+3+2
<=> 2(a+b+c)=16
<=> a+b+c=8 =>c=8-11=-3;a=8-3=5;b=8-2=6
=>a+b+b+c+c+a=11+3+2
=>2(a+b+c)=16
=>a+b+c=8
=>a=8-3=5
b=8-2=6
c=8-11=-3
a+b+b+c+c+a = 11+3+2
2(a+b+c) = 16
a+b+c = 8
ma a +b =11 suy ra c = -3
b +c = 3 suy ra a = 5
suy ra a = 6