9.
.设数列\(\{\)\(a_{n}\)\(\}\)的前\(n\)项和为\(S_{n}\).已知\(a\)\({\,\!}_{1}\)\(=a\)\((\)\(a\)\(\neq 3)\),\(a_{n+}\)\({\,\!}_{1}\)\(=S_{n}+\)\(3\)\({\,\!}^{n}\),\(n\)\(∈N\)\({\,\!}^{*}\).
\((1)\)设\(b_{n}=S_{n}-\)\(3\)\({\,\!}^{n}\),求数列\(\{\)\(b_{n}\)\(\}\)的通项公式\(;\)
\((2)\)若\(a_{n+}\)\({\,\!}_{1}\geqslant \)\(a_{n}\),求\(a\)的取值范围.