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 Post subject: Help re Sequences
PostPosted: Wed Sep 24, 2008 4:50 pm 
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Joined: Sun Nov 04, 2007 5:45 pm
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Location: Medway & Kent
My dd is stuck on her math homework. She is a year 7 but is following a year 8 curriculum (?). Anyway here is the question:

The nth term of sequences are given by the rules below. Use this to write down the first five terms of each sequence:
a. 2n-1
b. 2n+3
c.2n+2
d. 2n+1

Can anybody help me??

MM


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 Post subject:
PostPosted: Wed Sep 24, 2008 5:06 pm 
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Joined: Thu Jul 10, 2008 9:56 pm
Posts: 81
Simply put 1 into the equation, then 2 and so on to get the value of that term.

Example 2n-1

Term 1 ........ (2x1)-1 = 1
Term 2 .......... (2x2)-1 = 3

etc.


http://www.bbc.co.uk/schools/ks3bitesiz ... _2_4.shtml

This may help.


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 Post subject:
PostPosted: Wed Sep 24, 2008 5:06 pm 
n is the nuber in the sequence i.e. 1,2,3,4

so 1 is 2x1-1=1
2. 2x2-1=3

so unless I'm totally wrong :oops: the first 5 terms are 1,2,3,4,5.


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 Post subject:
PostPosted: Wed Sep 24, 2008 5:06 pm 
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Joined: Fri Mar 17, 2006 5:12 pm
Posts: 1300
Location: Birmingham
Just substitute 1, 2, 3, 4 & 5 for n in each expression and multiply out

You get for 2n-1 -> 1,3,5,7,9
For 2n+3 -> 5,7,9,11,13
For 2n+2 -> 4,6,8,10,12
For 2n+1 -> 3,5,7,9,11


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 Post subject:
PostPosted: Wed Sep 24, 2008 5:08 pm 
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Location: Medway & Kent
DD says thank you all very much!! Excellent response guys. :D


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 Post subject:
PostPosted: Wed Sep 24, 2008 6:13 pm 
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Joined: Thu Jul 10, 2008 9:56 pm
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Did you notice the amazing synchronisation of our responses!

What is the probability of getting three replies at exactly the same time (6.06pm) 16 minutes after posting.......

Pretty small I'd say!!!!!! :shock:


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 Post subject:
PostPosted: Wed Sep 24, 2008 6:14 pm 
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Joined: Sun Nov 04, 2007 5:45 pm
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Location: Medway & Kent
I know!!! Pretty spooky but cool... 8)


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 Post subject:
PostPosted: Wed Sep 24, 2008 6:21 pm 
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Joined: Mon Feb 12, 2007 1:21 pm
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Image

You might find the answer in here :lol:


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 Post subject:
PostPosted: Wed Sep 24, 2008 6:41 pm 
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Joined: Thu Jul 10, 2008 9:56 pm
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Brilliant! LOL! :lol:


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