( 4-9. The block diagram of a feedback control system is shown in Fig. 4P- 9. (a) Apply the SFG gain formula directly to the block diagram to find the transfer functions: Express Y(s) in terms of R(s) and N(s) when both inputs are applied simultaneously. (b) Find the desired relation among the transfer functions G,(s), G(s), G;(s), G4(s), H(s) and H(s) so that the output Y(s) is not affected by the disturbance signal N(s) at all. Rin Y(s) Y(s) R(S) NON(S) RO Figure 4P-9 Gin (08) Gls) Gyjs) H) Nisi Fly)