For the systems a)-d) below with output y(t) and inputu(t): Calculate the transfer function G(s) = Y(s)/U (s) Determine the poles of the transfer function and sketch the poles in

the complex plane Classify the system as either stable, unstable or marginally stable \text { a) } \ddot{y}+6 \dot{y}+25 y=5 \dot{u}(t) \text { b) } \ddot{y}+6 \dot{y}-25 y=-5 \dot{u}(t)+10 u(t) \text { c) } \ddot{y}+25 \boldsymbol{y}=3 \dot{u}(t) \text { d) } \ddot{y}+6 \dot{y}=3 u(t)