在直角坐标系\(xOy\)中,直线\(l:\begin{cases} & x=\dfrac{3}{5}t \\ & y=1+\dfrac{4}{5}t \end{cases}(t\)为参数\()\),以原点\(O\)为极点,\(x\)轴的正半轴为极轴建立极坐标系,曲线\(C\)的极坐标方程为\({{\rho }^{2}}\cos 2\theta =-4\)
\((1)\)求曲线\(C\)的直角坐标方程;
\((2)\)点\(P(0,1)\),直线\(l\)与曲线\(C\)交于\(M,N\)两点,求\(\dfrac{1}{\left| PM \right|}+\dfrac{1}{\left| PN \right|}\)的值.