Find all possible I/O equations. (left{begin{array}{l}ddot{theta}_{1}+frac{2}{3} dot{theta}_{1}+frac{1}{3}left(theta_{1}-theta_{2} ight)=u(t) theta_{2}-frac{1}{3}left(theta_{1}-theta_{2} ight)=0end{array}, u(t)= ight.) input, (theta_{2}=) output

Find all possible I/O equations.

\(\left\{\begin{array}{l}\ddot{\theta}_{1}+\frac{2}{3} \dot{\theta}_{1}+\frac{1}{3}\left(\theta_{1}-\theta_{2}\right)=u(t) \\ \theta_{2}-\frac{1}{3}\left(\theta_{1}-\theta_{2}\right)=0\end{array}, u(t)=\right.\) input, \(\theta_{2}=\) output