CHO A B C + + = 0 , TÍNH ( ) ( ) ( )2 2 2A B B C C A− + − + − 2 2A B C...

Bài 57: Cho a b c + + = 0 , Tính

( ) ( ) ( )

2 2 2

a b b c c a

− + − + −

2 2

a b c a b c ab bc ca

+ + + + + + +

= + + − + +

A a b c ab bc ca