已知函数\(f(x)=\dfrac{3x}{ax+b}\),\(f(1)=1\),\(f(\dfrac{1}{2})=\dfrac{3}{4}\),数列\(\{x_{n})\)满足\({{x}_{1}}=\dfrac{3}{2}\),\(x_{n+1}=f(x_{n}).\)
\((1)\)求\(x_{2}\),\(x_{3}\)的值;
\((2)\)求数列\(\{x_{n}\}\)的项公式;
\((3)\)证明:\(\dfrac{{{x}_{1}}}{3}+\dfrac{{{x}_{2}}}{{{3}^{2}}}+...+\dfrac{{{x}_{n}}}{{{3}^{n}}} < \dfrac{3}{4}\).