JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Mock Test - Binomial Theorem

  • question_answer
    If the \[{{6}^{th}}\]term in the expansion of \[{{\left( \frac{1}{{{x}^{8/3}}}+{{x}^{2}}{{\log }_{10}}x \right)}^{8}}\]is 5600, then x equals

    A) 1                     

    B) \[{{\log }_{e}}10\]

    C) 10                   

    D) x does not exist

    Correct Answer: C

    Solution :

    [c] It is given that \[{{6}^{th}}\]term in the expansion of \[{{\left( \frac{1}{{{x}^{8/3}}}+{{x}^{2}}{{\log }_{10}}x \right)}^{8}}\] \[^{8}{{C}_{5}}{{({{x}^{2}}lo{{g}_{10}}x)}^{5}}{{\left( \frac{1}{{{x}^{8/3}}} \right)}^{3}}=5600\] Or \[56{{x}^{10}}{{(lo{{g}_{10}}x)}^{5}}\frac{1}{{{x}^{8}}}=5600\] Or \[{{x}^{2}}{{(lo{{g}_{10}}x)}^{5}}=100\] Or \[{{x}^{2}}{{(lo{{g}_{10}}x)}^{5}}={{10}^{2}}{{(lo{{g}_{10}}10)}^{5}}\] Or \[x=10\]


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