MCQ
If $a,\;b,\;c$ are the positive integers, then $(a + b)(b + c)(c + a)$ is
  • A
    $ < 8abc$
  • $ > 8abc$
  • C
    $ = 8abc$
  • D
    None of these

Answer

Correct option: B.
$ > 8abc$
b
(b) Since $A.M. > G.M.$, we have

$\frac{{a + b}}{2} > \sqrt {ab} ,\;\frac{{b + c}}{2} > \sqrt {bc} $

and $\frac{{a + c}}{2} > \sqrt {ac} $.

Multiplying these inequalities, we get

$(a + b)(b + c)(c + a) > 8abc$.

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