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

  • question_answer
    If \[\frac{{{e}^{x}}}{1-x}={{B}_{0}}+{{B}_{1}}x+{{B}_{2}}{{x}^{2}}+...+{{B}_{n}}{{x}^{n}}\] then \[{{B}_{n}}-{{B}_{n-1}}\] is

    A) \[\frac{1}{n!}-\frac{1}{(n-1)!}\]

    B) \[\frac{1}{n!}\]

    C) \[\frac{1}{(n-1)!}\]

    D) \[\frac{1}{n!}+\frac{1}{(n-1)!}\]

    Correct Answer: B

    Solution :

    [b] We have \[(1-x)({{B}_{0}}+{{B}_{1}}x+{{B}_{2}}{{x}^{2}}+....)\] \[.....+{{B}_{n-1}}{{x}^{n-1}}+{{B}_{n}}{{x}^{n}}+...)\]             \[={{e}^{x}}=1+x+\frac{{{x}^{2}}}{2!}+\frac{{{x}^{3}}}{3!}+....+\frac{{{x}^{n}}}{n!}+.......(1)\] Hence equating the coefficients of \[{{x}^{n}}\] on both sides of (1) we get \[{{B}_{n}}-{{B}_{n-1}}=\frac{1}{n!}.\]


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