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JCECE Engineering JCECE Engineering Solved Paper-2012

  • question_answer
    The coefficient of \[{{x}^{n}}\] in the expansion of\[{{(1-x)}^{-2}}\]is

    A) \[\frac{{{2}^{n}}}{2!}\]                                  

    B) \[n+1\]

    C) \[n+2\]                

    D) \[2n\]

    Correct Answer: C

    Solution :

    We have,\[{{(1-x)}^{-2}}=1+2x+3{{x}^{2}}+...\]                 \[+(n+1){{x}^{n}}+(n+2){{x}^{n+1}}+...\] \[\therefore \]Coefficient of\[{{x}^{n+1}}\]is\[n+2\].


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