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

  • question_answer
    If p,q,r are in G.P and \[{{\tan }^{-1}}p\], \[{{\tan }^{-1}}q,{{\tan }^{-1}}r\]are in A.P. then p, q, r are satisfies the relation [DCE 2005]

    A) \[p=q=r\]

    B) \[p\ne q\ne r\]

    C) \[p+q=r\]

    D) None of these

    Correct Answer: A

    Solution :

      \[p,q,r\in \text{G}\text{.}\,\text{P}\text{.}\], \[\therefore {{q}^{2}}=pr\] Also \[{{\tan }^{-1}}p,{{\tan }^{-1}}q,\] \[{{\tan }^{-1}}r\in \]A.P. Þ \[{{\tan }^{-1}}p+{{\tan }^{-1}}r=2{{\tan }^{-1}}q\] Þ \[p+r=2q\Rightarrow p,q,r\] are in A.P. Now p, q, r are both in A.P and G.P., which is possible only, if \[p=q=r\].


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