2. Sample Papers
  3. KVPY

KVPY Sample Paper KVPY Stream-SX Model Paper-27

  • question_answer
    If \[\frac{a+b}{1-ab},\] \[b,\frac{b+c}{1-bc}\] are in A.P. then \[{{a}^{-1}},\] \[b,\] \[{{c}^{-1}}\]

    A) A.P.

    B) G.P.

    C) H.P.     

    D) None of these

    Correct Answer: A

    Solution :

    \[2b=\frac{a+b}{1-ab}+\frac{b+c}{1-bc}\]\[\Rightarrow 2a{{b}^{3}}c+2abc=a+c+a{{b}^{2}}+{{b}^{2}}c\]\[\Rightarrow 2abc\,\,({{b}^{2}}+1)=(a+c)(1+{{b}^{2}})\]\[\Rightarrow 2b=\frac{a+c}{ac}\Rightarrow 2b=\frac{1}{a}+\frac{1}{c}\]\[\Rightarrow \]\[{{a}^{-1}},\,\]\[b,\]\[{{c}^{-1}}\] are in A.P.


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