In simplifying a block diagram,remember the following.
1.The product of the transfer function in the feedforward direction must remain the same.
2.The product of the transfer function around the loob must remain the same.
Consider the system shown in Figure3-9(a).Simplify this diagram
By moving the summing point of the negative feedback loop cantaining outside the positive feedback loop containing we obtain Figure 3-9(b).Eliminating the positive feedback