Help re Sequences

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medwaymum
Posts: 827
Joined: Sun Nov 04, 2007 6:45 pm
Location: Medway & Kent

Help re Sequences

Post by medwaymum »

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
Mum007
Posts: 81
Joined: Thu Jul 10, 2008 10:56 pm

Post by Mum007 »

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.
T.i.p.s.y

Post by T.i.p.s.y »

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.
KenR
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Joined: Fri Mar 17, 2006 6:12 pm
Location: Birmingham

Post by KenR »

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
medwaymum
Posts: 827
Joined: Sun Nov 04, 2007 6:45 pm
Location: Medway & Kent

Post by medwaymum »

DD says thank you all very much!! Excellent response guys. :D
Mum007
Posts: 81
Joined: Thu Jul 10, 2008 10:56 pm

Post by Mum007 »

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:
medwaymum
Posts: 827
Joined: Sun Nov 04, 2007 6:45 pm
Location: Medway & Kent

Post by medwaymum »

I know!!! Pretty spooky but cool... 8)
Guest55
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Joined: Mon Feb 12, 2007 2:21 pm

Post by Guest55 »

Image

You might find the answer in here :lol:
Mum007
Posts: 81
Joined: Thu Jul 10, 2008 10:56 pm

Post by Mum007 »

Brilliant! LOL! :lol:
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