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#1 2006-10-27 06:34:26

Neha
Member
Registered: 2006-10-11
Posts: 173

Question

find the difference between
  P   and     P
6  4         6   1

how you do thissssssssssssssss
if u understand what it means by the way i wrote it


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#2 2006-10-27 07:06:12

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

mathdb1.jpg

now understand ?????


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#3 2006-10-27 07:43:01

Neha
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Registered: 2006-10-11
Posts: 173

Re: Question

helllllllp anyone get how ot do this?


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#4 2006-10-27 08:04:59

Ricky
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Registered: 2005-12-04
Posts: 3,791

Re: Question

You gotta give us a chance to respond.

Do you know what permutations are?  Do you know the formula for permutations?


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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#5 2006-10-27 08:26:39

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

yeah i saw in book it is ........like this

10P4 = 10 * 9 * 8 * 7 = 5040
then
4 * 3 * 2 * 1
then divide
10 * 9 * 8 * 7
---------------- = 210
4 * 3 * 2 * 1

like this right?


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#6 2006-10-27 08:38:09

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

formula equals
           n(n-1)(n-2)(n-3)...(n-r+1)           n!
nCr =----------------------------------- = -------
                         r!                            (n-r)!r!


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#7 2006-10-27 11:26:44

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

Re: Question

You got nCr right.  Now you gotta come up with a formula for nPr.  Trying to do it yourself can be very hard, and it's more often just given to you:

nPr = n! / (n-r)!


"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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#8 2006-10-30 04:43:48

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

ok sooooooooooooo

6P4 = 6! / (6 - 4) !  >>> 6! / 2!
and
6P1 = 6! / (6 - 1) ! >>> 6! / 5!

so tehy ask for the difference

the difference is ........... obvious right

Last edited by Neha (2006-10-30 04:44:00)


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#9 2006-10-31 04:16:34

unique
Member
Registered: 2006-10-04
Posts: 419

Re: Question

ok so ........

6! / 2! equals
720 / 2 which equals 360
and
6! / 5! equals
720 / 120 which equals 6

and they say find teh difference
then teh difference is 360 subtract 6 which then we have 354 .


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#10 2006-10-31 10:48:44

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

thanks unique...that looks right


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#11 2006-11-01 03:46:03

Neha
Member
Registered: 2006-10-11
Posts: 173

Re: Question

so such as this
FIND:
4P2

4P2 = n! / (n-r)!
4P2 = 4! / (4 - 2) !
4P2 = 4! / 2!
4P2 = 12
answer is 12


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