JEE Main & Advanced Mathematics Sequence & Series Question Bank Geometric Progression

  • question_answer
    The product of \[n\] positive numbers is unity. Their sum is  [MP PET 2000]

    A) A positive integer

    B) Equal to \[n+\frac{1}{n}\]

    C) Divisible by \[n\]

    D) Never less than

    Correct Answer: D

    Solution :

    Given \[{{x}_{1}}.{{x}_{2}}.{{x}_{3}}..........{{x}_{n}}=1\] \[\because \] \[\text{A}\text{.M}\text{.}\,\ge \text{G}\text{.M}\text{.}\] \ \[\left( \frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+......+{{x}_{n}}}{n} \right)\,\ge \,{{({{x}_{1}}.{{x}_{2}}.{{x}_{3}}.......{{x}_{n}})}^{\frac{1}{n}}}\] \[={{(1)}^{\frac{1}{n}}}=1\] \ \[{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+........+{{x}_{n}}\ge n\] \ \[{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+.......+{{x}_{n}}\] can never be less than n.


You need to login to perform this action.
You will be redirected in 3 sec spinner