3 3 3 1 2 2 2( )A B C+ + +2 2 2 3A B B + C C + A ≥ + +3 3 3A B C1 (...

5. 3 3 3 1 2 2 2

( )

a b c

+ + +

2 2 2 3

a b b + c c + a ≥ + +

3 3 3

1 ( )

a b c