Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-21

  • question_answer
    If \[{{a}^{x}}={{b}^{y}}={{c}^{z}}\]and \[{{b}^{2}}=ac,\]then y is equal to

    A)  \[\frac{xz}{x+z}\]        

    B)  \[\frac{xz}{2(x-z)}\]

    C)  \[\frac{xz}{2(z-x)}\]      

    D)  \[\frac{2xz}{(x+z)}\]

    Correct Answer: D

    Solution :

    Let \[{{a}^{x}}={{b}^{y}}={{c}^{z}}=k\] Then, \[a={{k}^{\frac{1}{x}}},\,\,b={{k}^{\frac{1}{y}}},\,\,c={{k}^{\frac{1}{z}}};\,\,{{b}^{2}}=ac\] \[\Rightarrow \]   \[\,{{\left( {{k}^{\frac{1}{y}}} \right)}^{2}}={{k}^{\frac{1}{x}}}\times {{k}^{\frac{1}{z}}}\] \[\Rightarrow \]   \[\,\frac{2}{y}=\frac{1}{x}+\frac{1}{z}=\frac{x+z}{xz}\] \[\Rightarrow \]   \[y=\frac{2xz}{\left( x+z \right)}\]


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