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Math Help - factorials

  1. #1
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    factorials

    hi,

    how do i do (2n-1)!/(2n+1)!
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  2. #2
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    n!= 1 \cdot 2 \cdot 3\cdot...\cdot (n-1)\cdot n
    Write this way (2n-1)! and (2n+1)!, then simplify and see what remains.
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  3. #3
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    so for (2n-1)! = 2n-1.2n where else for (2n+1)! = 2n+1.2n ?
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  4. #4
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    O.o No. You really read the first line?

    n! = the product of first n natural unzero numbers. So... (2n-1)!=?
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  5. #5
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    salohcinseah,

    I guess you din't get what veileen actually said.
    See

    n! = 1. 2.\dots.(n-1).n

    So

    (2n-1)!= 1.2.\dots.(2n).(2n-1)

    Similarly

    (2n+1)!= 1.2.\dots.(2n-1).(2n).(2n+1)

    So, now divide both and see what remains.
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  6. #6
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    i see so the answer will be 1/(2n+1)?
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  7. #7
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    amul28 - uhm, 2n > 2n-1 >.>

    (2n-1)!=1 \cdot 2 \cdot...\cdot(2n-3)\cdot (2n-2)\cdot (2n-1)

    The answer will be \frac{1}{2n(2n+1)}.
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  8. #8
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    my bad.
    you are correct.
    salohcinseah, please correct that.
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