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Math Help - The term of Number

  1. #1
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    Question The term of Number

    Could you help me to solve this :

    What is the 60th term of 23, -16, 9, -2, -5, 12, -19,...?
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  2. #2
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    Re: The term of Number

    Quote Originally Posted by AlvaJr View Post
    Could you help me to solve this :

    What is the 60th term of 23, -16, 9, -2, -5, 12, -19,...?
    the recurrence relation is

    $a_n=-(a_{n-1}+7 (-1)^n)$

    $a_1=23$

    you can dump this into excel or go to wolframalpha.com to find the 60th term.
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  3. #3
    MHF Contributor ebaines's Avatar
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    Re: The term of Number

    Nio need to use Excel or any other fancy tool. The even numbered terms have the sequence -16, -2, 12, ... Note that each even term is 14 greater than the preceeding even term. Hence the 60th term in the sequence, which is the 30th even term, will have the value: -16 + (29x14).
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  4. #4
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    Re: The term of Number

    Thank you for your help.
    I can solve this problem by using arithmetic formula.
    Un= a + (n-1)b
    Un= -16 + (n-1)14
    so, U30 = -16 + (29)14
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  5. #5
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    Re: The term of Number

    Thank you for your help.
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