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Mathematics: Post your doubts here!

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My doubt is just a confusion in the permutation combination how do we calculate for items not together .. what is the difference between using the way that
we make them together and subtract them from the arrangement of all (method 1).. or
multiplying by for eg we have 9 places and 4 items should not be together so 9P4 ?! (method 2)

.. why sometimes I get this wrong !!

for example here we use (method 2) in Q6 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_62.pdf


and here we use (method 1) in Q7 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_63.pdf


So can someone "Please" Explain what is the difference between this 2 methods and when to use each method .. thanks in Advance !! :)
 
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My doubt is just a confusion in the permutation combination how do we calculate for items not together .. what is the difference between using the way that
we make them together and subtract them from the arrangement of all (method 1).. or
multiplying by for eg we have 9 places and 4 items should not be together so 9P4 ?! (method 2)

.. why sometimes I get this wrong !!

for example here we use (method 2) in Q6 (iii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_62.pdf


and here we use (method 1) in Q7 (iii)
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s13_qp_63.pdf


So can someone "Please" Explain what is the difference between this 2 methods and when to use each method .. thanks in Advance !! :)

okay so method one which in my attachment is 3
is when Not all next to each other lets take an example
3 Blue pens and 4 green
Find the possible arrangements when not ALL green next to each other
we can have it like this
|||||||
but if its method 2 which is in my attachment 4
you cant have it like this you are suppose to have it
||||||| or any other way in which a green is not next to another green
BUT sometime both the methods work when you have
for example 3 blue and 2 green
just because the number is 2 that's why
 

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Messages
354
Reaction score
529
Points
103
okay so method one which in my attachment is 3
is when Not all next to each other lets take an example
3 Blue pens and 4 green
Find the possible arrangements when not ALL green next to each other
we can have it like this
|||||||
but if its method 2 which is in my attachment 4
you cant have it like this you are suppose to have it

||||||| or any other way in which a green is not next to another green
BUT sometime both the methods work when you have
for example 3 blue and 2 green
just because the number is 2 that's why
LOAAAAAAAAAADS OF THANKS !!!!!!!! :D :rolleyes::rolleyes:(y)(y):D:D:ROFLMAO:
 
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yes!! (- 41.4 + 52.24 )*2 = 21. something.

now if you did not put the - sign with the 41.4 then even that step marks will be allotted and
if you insist that where does that minus comes from than it is upto us. As these are some trigonometry rules we learnt in add maths.
Rutzaba
 
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yes!! (- 41.4 + 52.24 )*2 = 21. something.

now if you did not put the - sign with the 41.4 then even that step marks will be allotted and
if you insist that where does that minus comes from than it is upto us. As these are some trigonometry rules we learnt in add maths.
Rutzaba
cos haina to minus theta kiu lia hum ne/
 
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