ответ: a_{n}=3\cdot nan=3⋅n .
\begin{gathered}3,\ 6,\ 9,\ 12,\ 15\ ,...a_1=3a_2=6=3\cdot 2a_3=9=3\cdot 3a_4=12=3\cdot 4a_5=15=3\cdot 5\\a_{n}=3\cdot n\end{gathered}3, 6, 9, 12, 15 ,...a1=3a2=6=3⋅2a3=9=3⋅3a4=12=3⋅4a5=15=3⋅5an=3⋅n
ответ: a_{n}=3\cdot nan=3⋅n .
\begin{gathered}3,\ 6,\ 9,\ 12,\ 15\ ,...a_1=3a_2=6=3\cdot 2a_3=9=3\cdot 3a_4=12=3\cdot 4a_5=15=3\cdot 5\\a_{n}=3\cdot n\end{gathered}3, 6, 9, 12, 15 ,...a1=3a2=6=3⋅2a3=9=3⋅3a4=12=3⋅4a5=15=3⋅5an=3⋅n