JEE Main & Advanced Mathematics Binomial Theorem and Mathematical Induction Question Bank Critical Thinking

  • question_answer
    The middle term in the expansion of \[{{(1+x)}^{2n}}\] is  [Pb. CET 1998]

    A) \[\frac{1.3.5....(5n-1)}{n!}{{x}^{n}}\]

    B) \[\frac{2.4.6....2n}{n!}{{x}^{2n+1}}\]

    C) \[\frac{1.3.5....(2n-1)}{n!}{{x}^{n}}\]

    D) \[\frac{1.3.5....(2n-1)}{n!}{{2}^{n}}{{x}^{n}}\]

    Correct Answer: D

    Solution :

    Middle term of  \[{{(1+x)}^{2n}}\]is \[{{T}_{n+1}}={{\,}^{2n}}{{C}_{n}}{{x}^{n}}\] \[=\frac{(2n)!}{n!\,\,n!}{{x}^{n}}=\frac{1.3.5....(2n-1)}{n!}{{2}^{n}}{{x}^{n}}\].


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