已知\(|x_{1}-2| < 1\),\(|x_{2}-2| < 1\),\({{x}_{1}}\ne {{x}_{2}}\)
\((1)\)求证:\(2 < x\)\({\,\!}_{1}\)\(+x\)\({\,\!}_{2}\)\( < 6\),\(|x\)\({\,\!}_{1}\)\(-x\)\({\,\!}_{2}\)\(| < 2;\)
\((2)\)若\(f(x)=x\)\({\,\!}^{2}\)\(-x+1\),求证:\(|x\)\({\,\!}_{1}\)\(-x\)\({\,\!}_{2}\)\(| < |f(x\)\({\,\!}_{1}\)\()-f(x\)\({\,\!}_{2}\)\()| < 5|x\)\({\,\!}_{1}\)\(-x\)\({\,\!}_{2}\)\(|.\)