Answer
See below, $d=2$.
$-3,-1,1,3$
Work Step by Step
1. Based on the given expression, we have $s_n-s_{n-1}=2n-5-(2(n-1)-5)=2$, thus this sequence is arithmetic and the common difference is $d=2$.
2. The first four terms are $-3,-1,1,3$
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