8.
已知函数\(f(x)=e^{x}\),\(g(x)=\ln x\),\(h(x)=kx+b\).
\((1)\)当\(b=0\)时,若对任意\(x∈(0,+∞)\)均有\(f(x)\geqslant h(x)\geqslant g(x)\)成立,求实数\(k\)的取值范围;
\((2)\)设直线\(h(x)\)与曲线\(f(x)\)和曲线\(g(x)\)相切,切点分别为\(A(x_{1},f(x_{1}))\),\(B(x_{2},g(x_{2}))\),其中\(x_{1} < 0\).
\(①\)求证:\(x_{2} > e\);
\(②\)当\(x\geqslant x_{2}\)时,关于\(x\)的不等式\(a(x_{1}-1)+x\ln x-x\geqslant 0\)恒成立,求实数\(a\)的取值范围.