6.
\((1)\)已知向量\(\overrightarrow{a}=\left( 6,-2 \right),\overrightarrow{b}=\left( 3,m \right)\),且\(\overrightarrow{a}/\!/\overrightarrow{b}\),则\(\left| \overrightarrow{a}-\overrightarrow{b} \right|=\)_________.
\((2)\)已知\(\Delta ABC\)的三边长分别为\(3\),\(5\),\(7\),则该三角形的外接圆半径等于_________
\((3)\)若函数\(f\left( x \right)=\begin{cases} {{x}^{2}}-a\ \ x\leqslant 0 \\ \dfrac{x}{2}-a+\ln x\ \ x > 0 \end{cases}\)在区间\(\left( -2,2 \right)\)上有两个零点,则实数\(a\)的取值范围为_________.
\((4)\)已知数列\(\{{{a}_{n}}\}\)与\(\{{{b}_{n}}\}\)满足\({{a}_{n}}=2{{b}_{n}}+3(n\in {{N}^{*}})\),若\(\{{{b}_{n}}\}\)的前\(n\)项和为\({{S}_{n}}=\dfrac{3}{2}({{3}^{n}}-1)\)且\(\lambda {{a}_{n}} > {{b}_{n}}+36(n-3)+3\lambda \)对一切\(n\in {{N}^{*}}\)恒成立,则实数\(\lambda \)的取值范围是_______\(.\)