Help with the nth term for 1, -1, 1, -1, ... please
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- Posts: 19
- Joined: Sun Nov 30, 2008 7:38 pm
Help with the nth term for 1, -1, 1, -1, ... please
My son has this for homework and I am stuck, please help. My method of finding the differences does not work.
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- Posts: 19
- Joined: Sun Nov 30, 2008 7:38 pm
No - when signs alternate like this there is usually a power involved - and that's where the difference method breaks down.
ie 2,4,8,16 is the powers of two - if you look at the differences you get 2,4,8 ... which is a bit of a clue.
I would expect that unless they have seen this 'trick' that few chilldren would get the question right so your child might get asked how they worked it out!! That's what I do when I set one like this
ie 2,4,8,16 is the powers of two - if you look at the differences you get 2,4,8 ... which is a bit of a clue.
I would expect that unless they have seen this 'trick' that few chilldren would get the question right so your child might get asked how they worked it out!! That's what I do when I set one like this