6.
向量\( \overrightarrow{a}=(3,2)\),\( \overrightarrow{b}=(-1,2)\),\( \overrightarrow{c}=(4,1)\):
\((1)\)求满足\( \overrightarrow{a}=m \overrightarrow{b}+n \overrightarrow{c}\)的实数\(m\),\(n\);
\((2)\)若\(( \overrightarrow{a}+k \overrightarrow{c})/\!/(2 \overrightarrow{b}- \overrightarrow{a})\),求实数\(k\).