[(A – B)2 + (B – C)2 + (C – A)2]MÀ A3 + B3 + C3 – 3ABC = 1

2 . - DAP AN DE THI GVG TINH BAC NINH NAM 12 13
Toán DAP AN DE THI GVG TINH BAC NINH NAM 12 13

2

.(a + b + c).[(a – b)

2

+ (b – c)

2

+ (c – a)

2

]Mà a

3

+ b

3

+ c

3

– 3abc =

1