Banking Quantitative Aptitude Sample Paper Quantitative Aptitude Sample Paper-47

  • question_answer
    If \[{{x}^{x\sqrt{x}}}={{(x\sqrt{x})}^{x}},\] then x is equal to [SSC (CGL) 2005]

    A) \[\frac{4}{9}\]                          

    B) \[\frac{2}{3}\]

    C) \[\frac{9}{4}\]  

    D) \[\frac{3}{2}\]

    Correct Answer: C

    Solution :

    \[{{x}^{x\sqrt{x}}}={{(x\sqrt{x})}^{x}}\]\[\Rightarrow \]\[{{x}^{x.{{x}^{1/2}}}}={{(x.{{x}^{1/2}})}^{x}}\]
    \[\Rightarrow \]\[{{x}^{x\,\,\left( 1+\frac{1}{2} \right)}}={{({{x}^{1\,\,+\,\,1/2}})}^{x}}\]\[\Rightarrow \]\[{{x}^{{{x}^{3/2}}}}={{({{x}^{3/2}})}^{x}}={{x}^{3x/2}}\]
    \[\Rightarrow \]\[{{x}^{{{x}^{3/2}}}}={{x}^{3x/2}}\]
    Base is same.
    \[\therefore \]      \[{{x}^{3/2}}=\frac{3x}{2}\]
    \[\Rightarrow \]\[{{x}^{3/2}}-\frac{3x}{2}=0\]\[\Rightarrow \]\[x\left( {{x}^{\frac{1}{2}}}-\frac{3}{2} \right)=0\]\[\Rightarrow \]\[x=0\]
    or         \[{{x}^{1/2}}=\frac{3}{2}\]\[\Rightarrow \]\[x={{\left( \frac{3}{2} \right)}^{2}}=\frac{9}{4}\]
    \[x=0\] given indeterminate value.
    \[\therefore \]\[x=\frac{9}{4}\]


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