Exercise 3.2 Biasing a circuit with two cascaded NPNs

a)

An answer:
Original situation: IC2 = βfeIB2 IB2 = IE1 IE1 = (βfe + 1)IB1 IB1 = V CC V B1 Rx V B1 1.2V IC2 = βfe(βfe + 1)V CC 1.2V Rx

Modified situation:

IC2 = βfeIB2 IB2 = IE1 IE1 = V CC V B1 Rx V B1 1.2V IC2 = βfe V CC 1.2V Rx

It follows from these relations that IC2 is changed quite a lot when applying the described circuit modification.