1.
已知函数\(f\left( x \right)=\dfrac{1}{2}{{x}^{2}}\),\(g\left( x \right)=a\ln x\).
\((1)\) 若曲线\(y=f\left( x \right)-g\left( x \right)\)在\(x=1\)处的切线方程为\(6x-2y-5=0\),求实数\(a\)的值\(;\)
\((2)\) 设\(h\left( x \right)=f\left( x \right)+g\left( x \right)\),若对任意两个不相等的正数\({{x}_{1}},{{x}_{2}},\)都有\(\dfrac{h({{x}_{1}})-h({{x}_{2}})}{{{x}_{1}}-{{x}_{2}}} > 2\)恒成立,求实数\(a\)的取值范围\(;\)
\((3)\) 若在\(\left[ 1,e \right]\)上存在一点\({{x}_{0}}\),使得\({f}{{{'}}}({{x}_{0}})+\dfrac{1}{{f}{{{'}}}({{x}_{0}})} < g({{x}_{0}})-{g}{{{'}}}({{x}_{0}})\)成立,求\(a\)的取值范围.