JEE Main & Advanced Mathematics Sequence & Series Question Bank Relation between AP., GP. and HP.

  • question_answer
    If the arithmetic and geometric means of a and b be \[A\] and \[G\] respectively, then the value of \[A-G\] will be

    A) \[\frac{a-b}{a}\]

    B) \[\frac{a+b}{2}\]

    C) \[{{\left[ \frac{\sqrt{a}-\sqrt{b}}{\sqrt{2}} \right]}^{2}}\]

    D) \[\frac{2ab}{a+b}\]

    Correct Answer: C

    Solution :

    Arithmetic mean of \[a\] and \[b=A=\frac{a+b}{2}\] and geometric mean \[G=\sqrt{ab}\] Then \[A-G=\frac{a+b}{2}-\sqrt{ab}\]\[=\frac{a+b-2\sqrt{ab}}{2}\] \[=\frac{{{(\sqrt{a})}^{2}}+{{(\sqrt{b})}^{2}}-2(\sqrt{a})(\sqrt{b})}{2}={{\left[ \frac{\sqrt{a}-\sqrt{b}}{\sqrt{2}} \right]}^{2}}\]


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