Answer
$5$
Work Step by Step
Let's note the arithmetic sequence by $\{a_n\}$ and the common difference by $d$. We are given:
$$\begin{cases}
a_4=11\\
a_6=17.
\end{cases}$$
We have:
$$\begin{cases}
a_2=a_1+d\\
a_4=a_1+3d=11\\
a_6=a_1+5d=17.
\end{cases}$$
We notice that
$$a_4-a_2=2d=a_6-a_4=2d.$$
Since $a_4-a_2=a_6-a_4$ we can calculate $a_2$ directly, without calculating $a_1$ and $d$:
$$\begin{align*}
11-a_2&=17-11\\
11-a_2&=6\\
a_2&=5.
\end{align*}$$
So the second term is $5$.