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# proof question

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1. prove that the (2n+1)th term of the sequence Un=n^2-1 is a multiple of 4.
the answer is at the back of the text book but I dont understand how to answer it.
2. Huuuuulp me plz
3. sub (2n+1) into the n of the sequence, multiply out and simplify - it should hopefully be obvious what to do next once you do this
4. (Original post by KINGYusuf)
So Un=n^2 -1

So U(2n+1) = (2n+1)^2 -1

So U(2n+1) = 4n^2 + 4n

So U(2n+1) = 4(n^2 + n)

therefore a multiple of 4
thanks but why did you multipy (2n+1) by 2-1?
5. (Original post by p29)
thanks but why did you multipy (2n+1) by 2-1?
I just subbed (2n+1) into the nth term that they gave you

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Updated: October 10, 2016
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