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Math Help - do you know the properties of summation

  1. #1
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    do you know the properties of summation

    if you multiply two summation notation
    ex.

    (summation (x)) *(summation(y)) do you get (sumation (xy)) ??
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  2. #2
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    Hello,
    Quote Originally Posted by pandakrap View Post
    if you multiply two summation notation
    ex.

    (summation (x)) *(summation(y)) do you get (sumation (xy)) ??
    Is (a+b)*(c+d) equal to ac+bd ?
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  3. #3
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    no. it = ac + cd + ad + bd
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  4. #4
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    Quote Originally Posted by pandakrap View Post
    no. it = ac + cd + ad + bd
    So try :
    \left(\sum_{i=1}^2 a_i \right) \times \left(\sum_{i=1}^2 b_i \right)=(a_1+a_2) \times (b_1+b_2)

    \sum_{i=1}^2 a_i b_i=a_1b_1+a_2b_2

    is (a_1+a_2) \times (b_1+b_2) equal to a_1b_1+a_2b_2 ?
    And hence is your formula correct ?


    You can see here : Cauchy product - Wikipedia, the free encyclopedia for the formula of the product of two summations
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