RAJASTHAN ­ PET Rajasthan PET Solved Paper-2006

  • question_answer
    The solution of equation \[{{9}^{x}}-{{2}^{x+\frac{1}{2}}}={{2}^{x+\frac{3}{2}}}-{{3}^{2x-1}}\]is

    A)  \[{{\log }_{e}}\left( \frac{9}{\sqrt{8}} \right)\]

    B)  \[{{\log }_{9}}\left( \frac{9}{\sqrt{8}} \right)\]

    C)  \[{{\log }_{(9/2)}}\left( \frac{9}{\sqrt{8}} \right)\]

    D)  None of these

    Correct Answer: C

    Solution :

     Given, equation is \[{{9}^{x}}-{{2}^{x+\frac{1}{2}}}={{2}^{x+\frac{3}{2}}}-{{3}^{2x-1}}\] \[\Rightarrow \] \[{{9}^{x}}-{{2}^{x}}.\sqrt{2}={{2}^{x}}\sqrt{8}-{{9}^{x}}{{.3}^{-1}}\] \[\Rightarrow \] \[{{9}^{x}}+\frac{{{9}^{x}}}{3}={{2.2}^{x}}\sqrt{2}+{{2}^{x}}\sqrt{2}\] \[\Rightarrow \] \[\frac{4}{3}{{9}^{x}}=3\sqrt{2}{{.2}^{x}}\] \[\Rightarrow \] \[{{\left( \frac{9}{2} \right)}^{x}}=\frac{9\sqrt{2}}{4}\] \[\Rightarrow \] \[{{\left( \frac{9}{2} \right)}^{x}}=\frac{9}{2\sqrt{2}}=\frac{9}{\sqrt{8}}\] \[\Rightarrow \] \[x={{\log }_{(9/2)}}\left( \frac{9}{\sqrt{8}} \right)\]


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