Answer
$\{34,51,68,...\}$ is an arithmetic sequence with common difference $d=17$
Work Step by Step
In the given sequence, $\{
34,51,68,...
\},$ the differences of a term and its previous term are
\begin{align*}\require{cancel}
a_2-a_1&=
51-34
\\&=
17
,\\\\
a_3-a_2&=
68-51
\\&=
17
.\end{align*}
Since the differences of a term and its previous term are the same, then $
\{34,51,68,...\}$ is an arithmetic sequence with common difference $d=17
.$
