The overall transfer function of the system in Figure, is

For what values of $$'a'$$ does the system shown in figure have a zero steady state error $$\left[ {i.e.,\mathop {Lim}\limits_{t \to \infty } \,\,E\left( t \right)} \right]$$ for a step input?

For what range of $$K$$ is the following system (Figure) asymptotically stable Assume $$K \ge 0$$

Which of the following figure(s) represent valid root loci in the $$s$$ - plane for positive $$K?$$ Assume that the system has transfer function with real coefficient.