RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    If\[{{a}^{x}}={{b}^{y}}={{c}^{z}}={{d}^{u}}\]and a, b, c, d are in GP, then\[x,\text{ }y,\text{ }z\]are in

    A)  AP             

    B)  GP

    C)  HP             

    D)  None of these

    Correct Answer: C

    Solution :

     \[{{a}^{x}}={{b}^{y}}={{c}^{z}}={{d}^{u}}=k\] (suppose) \[\therefore \]\[a={{k}^{1/x}},b={{k}^{1/y}},c={{k}^{1/z}},d={{k}^{1/u}}\] Since a, b, c, d are in GP. \[\therefore \] \[{{b}^{2}}=ac\] \[\Rightarrow \] \[{{k}^{2/y}}={{k}^{1/x}}{{k}^{1/z}}\] \[\Rightarrow \] \[{{k}^{2/y}}={{k}^{1/x+1/z}}\] \[\Rightarrow \] \[\frac{2}{y}=\frac{1}{x}+\frac{1}{z}\] \[\therefore \]\[x,y,z\] are in HP.


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