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Homework Help: Use sigma notation for expression

  1. Apr 7, 2009 #1
    1. The problem statement, all variables and given/nknown data
    Find a formula for the expression. Use sigma notation.
    (x + 1/y)n

    3. The attempt at a solution

    Not sure how to do this we have only dealt with sigma notation involving only n as a variable
  2. jcsd
  3. Apr 8, 2009 #2


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    Homework Helper
    Gold Member

    Use the binomial theorem to expand the expression.


    [tex] \sum_{n=1}^{5} x^n = x + x^2 + x^3 + x^4 + x^5 [/tex]​

    Notice that although x is a variable, it does not vary from term to term. The only thing that varies from term to term is the exponent. Your problem is similar.
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