A3 + B3 + C3 – 3ABC = (A + B + C)

1) - DAP AN DE THI GVG TINH BAC NINH NAM 12 13
Toán DAP AN DE THI GVG TINH BAC NINH NAM 12 13
1) Ta có: a

3

+ b

3

+ c

3

– 3abc = (a + b + c).(a

2

+ b

2

+ c

2

– ab – bc – ca)

1