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Math Help - Sigma Help?

  1. #1
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    Exclamation Sigma Help?

    Hi
    I forgot how to solve sigma problems and these are one of the last problems I need to solve for my AP Calc summer assignment. If someone could help, I would greatly appreciate it

    The directions say to expand and simplify:

    a)

    4
    E n2 / 2
    n=0




    b)
    1
    E 1/n^3
    n=1


    I am pretty sure you start off with substituting (n=..) for n but how would I continue the problem?

    Thanks for helping!
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  2. #2
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    Quote Originally Posted by habibixox View Post
    Hi
    I forgot how to solve sigma problems and these are one of the last problems I need to solve for my AP Calc summer assignment. If someone could help, I would greatly appreciate it

    The directions say to expand and simplify:

    a)

    4
    E n2 / 2
    n=0




    b)
    1
    E 1/n^3
    n=1

    if I interpreted your first summation correctly ...

    \displaystyle \sum_{n=0}^4 \frac{n^2}{2} = \frac{1}{2} \sum_{n=0}^4 n^2 = \frac{1}{2}(0^2 + 1^2 + 2^2 + 3^2 + 4^2)

    get the idea?
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  3. #3
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    Awesome! Yes, I do, thank you
    It refreshed my memory :P

    so would the second one be this?

    1
    E 1/n^3
    n=1

    1
    1E n^3 = 1(0^2 + 1^2) = 1?

    n=1
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  4. #4
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    Quote Originally Posted by habibixox View Post
    Awesome! Yes, I do, thank you
    It refreshed my memory :P

    so would the second one be this?

    1
    E 1/n^3
    n=1

    1
    1E n^3 = 1(0^2 + 1^2) = 1?

    n=1
    incorrect.



    \displaystyle \sum_{n=1}^1 \frac{1}{n^3} = \frac{1}{1^3} = 1

    you need some review on your own ...

    Algebra II Recipe: Using Summation Notation
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  5. #5
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    Quote Originally Posted by skeeter View Post
    incorrect.



    \displaystyle \sum_{n=1}^1 \frac{1}{n^3} = \frac{1}{1^3} = 1

    you need some review on your own ...

    Algebra II Recipe: Using Summation Notation
    thank you for your help! it means a lot I reviewed that website, and searched for other practice problems. Thanks again!
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