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Math Help - Formula for the sequence

  1. #1
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    Formula for the sequence

    Hello, can someone please help me find the formula for the sequence?

    I know the difference is (-2/3), but I can't seem to figure out the formula.

    Thanks,
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  2. #2
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    Re: Formula for the sequence

    The ratio is (-2/3)

    the nth term is given by (-8)* \cdot (-2/3)^{n-1}
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  3. #3
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    Re: Formula for the sequence

    Quote Originally Posted by l flipboi l View Post
    Hello, can someone please help me find the formula for the sequence? I know the difference is (-2/3), but I can't seem to figure out the formula.
    Try a_n=\frac{(-2)^{n+3}}{3^{n}},~n=0,1,\cdots
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  4. #4
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    Re: Formula for the sequence

    Hi,
    The nth term is given by Tn=a+(n-1)d
    =-8+(n-1)(-2/3)
    =-11/3(2+n).
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  5. #5
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    Re: Formula for the sequence

    Quote Originally Posted by Plato View Post
    Try a_n=\frac{(-2)^{n+3}}{3^{n}},~n=0,1,\cdots
    thx, but n is suppose to start at 1.

    so the first term a1 = -8.
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  6. #6
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    Re: Formula for the sequence

    thanks!
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  7. #7
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    Re: Formula for the sequence

    Quote Originally Posted by l flipboi l View Post
    thx, but n is suppose to start at 1.

    so the first term a1 = -8.
    That's an easy fix... (!)
    Replace "n" with "n - 1" in P's solution.
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  8. #8
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    Re: Formula for the sequence

    Quote Originally Posted by deepashree View Post
    Hi,
    The nth term is given by Tn=a+(n-1)d
    =-8+(n-1)(-2/3)
    =-11/3(2+n).
    fyi, the sequence is geometric, not arithmetic.
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  9. #9
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    Re: Formula for the sequence

    Thanks, everyone!
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