A large fraction of mass-produced differential amplifier modules employing 20-kΩ collector resistors is found to have an input offset voltage ranging from +2 mV to -2 mV. By what amount must one collector resistor be adjusted to reduce the input offset to zero? If an adjustment mechanism is devised that raises one collector resistance while correspondingly lowering the other, what resistance change is needed? If a potentiometer connected as shown in Fig. P9.81 is used, what value of potentiometer resistance (specified to 1 significant digit) is needed? Assume that the offset is entirely due to the finite tolerance of RC.