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Old 02-04-2004, 09:26 PM   #1 (permalink)
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help with factorials

can someone tell me how [(n+1)!]^2 = ((n+1)^2)(n!)^2 ? I'm in that part of calculus where we do the stupid sequences and series, and I see a lot of factorials, and i have no idea how to manipulate them properly

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Old 02-04-2004, 09:47 PM   #2 (permalink)
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Quote:
can someone tell me how [(n+1)!]^2 = ((n+1)^2)(n!)^2 ? I'm in that part of calculus where we do the stupid sequences and series, and I see a lot of factorials, and i have no idea how to manipulate them properly

great, now i have something to look forward to this semester in calculus
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Old 02-04-2004, 10:03 PM   #3 (permalink)
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oh, I promise you, it's all FUN, FUN, FUN
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Old 02-05-2004, 12:01 AM   #4 (permalink)
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Jesus, why do you need that stuff in life?
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Old 02-05-2004, 12:03 AM   #5 (permalink)
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you don't, but they force you to learn it anyways
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Old 02-05-2004, 02:23 AM   #6 (permalink)
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Start with the Right Side, make it equal the left.

Right Side.
n! = 1*2*3*......n
(n!)^2 = (1*2*3....n)(1*2*3....n)
(n+1)^2 = (n+1)(n+1)

=> (n+1)(n+1)(1*2*3....n)(1*2*3...n)
=> (n+1)(1*2*3....n)(n+1)(1*2*3....n)
=> (1*2*3.....n)(n+1) * (1*2*3.....n)(n+1)
=> (1*2*3.....n*n+1) * (1*2*3....n*n+1)
=> (1*2*3.....n*n+1)^2
=> ((n+1)!)^2

Follow that?
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Old 02-05-2004, 03:36 AM   #7 (permalink)
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[shudders]... I remember them bad old days.

L.A.F, you have my deepest sympathies!

Nice workthrough though jkrohn!
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Old 02-05-2004, 08:14 AM   #8 (permalink)
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(n+1)! = (n!)(n+1) by definition. (Think about it: the product of the first n positive integers, times the (n+1)st integer, is the product of the first n+1 integers.)

Now square both sides. Presto!
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Old 02-05-2004, 05:35 PM   #9 (permalink)
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yes, I'm kind off ashamed for asking this question now, I looked at the factorial a bit more closer and then I realized it was just a simjple factoring out of (n+1)^2....thanks for the help though...

BTW, I still ahte series, sequences and factorials
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Old 02-05-2004, 05:39 PM   #10 (permalink)
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Ouch! time for a nap...
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