3．
\((1)\int_{1}^{2}{\dfrac{1}{x}}dx=\)__________．
\((2)\)已知等差数列\(\left\{ {{a}_{n}} \right\}\)的通项公式为\({{a}_{n}}=3n-5\)，则\({{\left( 1+x \right)}^{5}}+{{\left( 1+x \right)}^{6}}+{{\left( 1+x \right)}^{7}}\)的展开式中，含\({{x}^{4}}\)项的系数是该数列的第_________项\(.\)
\((3)\)已知随机变量\(X～B(4,p)\)若\(E\left( X \right)=2,\)则\(D\left( X \right)=\)__________．
\((4)S= \sqrt{1+ \dfrac{1}{{1}^{2}}+ \dfrac{1}{{2}^{2}}}+ \sqrt{1+ \dfrac{1}{{2}^{2}}+ \dfrac{1}{{3}^{2}}}+...+ \sqrt{1+ \dfrac{1}{{2018}^{2}}+ \dfrac{1}{{2019}^{2}}} \)的值为__________．