设函数\(f_{n}(x)=x^{n}+bx+c(n∈N^{*},b\)、\(c∈R)\).
\((1)\)当\(n=2\),\(b=1\),\(c=-1\)时,求函数\(f_{n}(x)\)在区间\((\dfrac{1}{2},1)\)内的零点;
\((2)\)设\(n\geqslant 2\),\(b=1\),\(c=-1\),证明:\(f_{n}(x)\)在区间\((\dfrac{1}{2},1)\)内存在唯一的零点;
\((3)\)设\(n=2\),若对任意\(x_{1}\),\(x_{2}∈[-1,1]\),有\(|f_{1}(x_{1})-f_{2}(_{x2})|\leqslant 4\),求\(b\)的取值范围.