JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Solution of quadratic equations and Nature of roots

  • question_answer
    The solution set of the equation \[{{x}^{{{\log }_{x}}{{(1-x)}^{2}}}}=9\] is [Pb. CET 2003]

    A) {- 2, 4}

    B) {4}

    C) {0, - 2, 4}

    D) None of these

    Correct Answer: A

    Solution :

    \[{{x}^{{{\log }_{x}}(1-x)}}^{2}=9\] Þ  \[{{\log }_{x}}(9)={{\log }_{x}}{{(1-x)}^{2}}(\because {{a}^{x}}=N\,\,\,\Rightarrow {{\log }_{a}}N=x)\] Þ \[9={{(1-x)}^{2}}\,\,\,\Rightarrow 1+{{x}^{2}}-2x-9=0\] Þ \[{{x}^{2}}-2x-8=0\]Þ \[(x+2)(x-4)=0\] Þ  \[x=-2\,,4\].


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