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

  • question_answer
    The coefficient of \[{{x}^{m}}\] in \[{{(1+x)}^{m}}+{{(1+x)}^{m+1}}+......+{{(1+x)}^{n}},m\le n\] is

    A) \[^{n+1}{{C}_{m+1}}\]

    B) \[^{n-1}{{C}_{m-1}}\]

    C) \[^{n}{{C}_{m}}\]     

    D) \[^{n}{{C}_{m+1}}\]

    Correct Answer: A

    Solution :

    [a] \[^{m}{{C}_{m}}+{{\,}^{m+1}}{{C}_{m}}+.....+{{\,}^{n}}{{C}_{m}}\] \[{{=}^{m+1}}{{C}_{m+1}}+{{\,}^{m+1}}{{C}_{m}}+.....+{{\,}^{n}}{{C}_{m}}\] \[{{=}^{m+2}}{{C}_{m+1}}+{{\,}^{m+2}}{{C}_{m}}+.....+{{\,}^{n}}{{C}_{m}}\] \[={{\,}^{n}}{{C}_{m+1}}+{{\,}^{n}}{{C}_{m}}={{\,}^{n+1}}{{C}_{m+1}}\]


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