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Thread: factorial

  1. Feb 6th, 2003, 04:23 PM #1
    bugzpodder
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    factorial

    5/7=a2/2!+a3/3!+a4/4!+a5/5!+a6/6!+a7/7!

    given that 0<=ai<i
    find all the unknown terms. i could do this question using trial and error but it isn't very nice. any ingenious methods out there?
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  2. Feb 8th, 2003, 03:07 AM #2
    sql_lall
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    (2520*a2 + 840*a3 +210*a4 + 42*a5 + 7*a6 + a7) /7! =5/7 (put whole side over 7!)

    => (2520*a2 + 840*a3 +210*a4 + 42*a5 + 7*a6 + a7) = 5*7!/7

    =>(2520*a2 + 840*a3 +210*a4 + 42*a5 + 7*a6 + a7) = 3600

    and easy from there
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  3. Feb 8th, 2003, 12:17 PM #3
    kedaman
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    ai= i! 5/7 % i

    a2=1
    a3=1
    a4=1
    a5=0
    a6=4
    a7=2
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