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Hello,
I'm 14 years old and am taking my KS3 moc maths SATs on Monday so as I've been on holiday all this week i've been revising. I was revising how to find the nth term of a sequence and I found it very hard to memorise the method that my teachers taught me to do at school. I have a revision guide from CGP Books and in it suggested that I learnt this formula:
a+(n-1)d+0.5(n-1)(n-2)C
a=The first term in the sequence
d=The difference between the first and second terms in a sequence
c=The change between one difference and the next.
I found that this was a much easier way to work it out, and after doing all the practise questions on the revision guide I searched on the internet to find a couple more questions for me to practise with. Whilst I was looking I came across this webpage: http://www.bbc.co.uk/schools/ks3bitesize/s...ths/46144.shtml
Which suggests that the formula doesn't always work for all number sequences. I don't understand the reply that the SOS teacher wrote and also why would CGP Books teach you a formula that doesn't work every time? So does this formula work or not? Or does the formula only not work for a particular sequence (e.g. triangle numbers or x3 for example).
I'd really appreciate it if I can have some replys by Monday (tommorow) because that's when my test is!
Thank you,
Melanie:D
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