5设${X}_{1}$,${X}_{2}$,···,${X}_{n}$是来自总体X的样本,${x}_{1}$,${x}_{2}$,···,${x}_{n}$是样本观测值,求下列总体X的概率密度中未知参数$\theta $的矩估计量和最大似然估计量.(1)$f\left(x;\theta \right)=\left\{\begin{array}{l}\left(\theta +1...