Applying the AM-GM Inequality - LearnMathsFree

In this video, we'll use the AM-GM inequality to prove another inequality on three positive real numbers a, b, c, that satisfy abc = 1.

[steveroger]

If you add it... you get thrice of ab2 + bc2 +ac2 and if you divide a+b+c by three you have your exact answer
ab2 + bc2 +ac2 is not greater than or equal to a+b+c

[shujamukhtar]

can you explain the logic behind using 3?