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Math Help - What is the sequence formula?

  1. #1
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    What is the sequence formula?

    3, -4, 7, -12, 19, ...

    What is the next number in the sequence? What is the formula for the nth term of the sequence?

    Thanks in advance!
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  2. #2
    Super Member Deadstar's Avatar
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    -28

    Will think of definite formula for nth term. Hold on.
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  3. #3
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    Quote Originally Posted by meggnog View Post
    3, -4, 7, -12, 19, ...

    What is the next number in the sequence? What is the formula for the nth term of the sequence?

    Thanks in advance!
    Hi there, consider the following.

    The absolute differences from each term follows a pattern 1,3,5,7,\dots

    Every the sign of every second term alternates. And looking at the differences after breaking the patterns into positive and negative numbers you get are 4,8,12,\dots

    Spoiler:
    The next term is -28
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  4. #4
    Super Member Deadstar's Avatar
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    Quote Originally Posted by pickslides View Post
    Hi there, consider the following.

    The absolute differences from each term follows a pattern 1,3,5,7,\dots

    Every the sign of every second term alternates. And looking at the differences after breaking the patterns into positive and negative numbers you get are 4,8,12,\dots

    Spoiler:
    The next term is -28
    Is there a formula to generate arithmetic sequences? I think it's usually recurrence relationships but maybe you can see something...

    Difference between |nth| term and |(n-1)th| term is 2n-3...
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