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proof question

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    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.
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    Huuuuulp me plz
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    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
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    (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?
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    (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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