1. Given the first n terms of a sequence and Sn = n square + n-1, is it an arithmetic sequence?
(^ 2) is the square
Because s n-1 = (n-1) ^ 2 + n-1-1
S n = n^2 +n-1
So S N - s n-1 = an
n^2 +n-1-n^2 +2n-1+2-n=an
2n=an
So an = 2n
Is an arithmetic sequence
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