I am familiar with the concept of the internal resistance of a voltage source, but what is meant by the input impedance?
... you appear to be asked to design a circuit using an op-amp - the circuit in question has two voltage sources in it - which should have some information about frequency and phase as well and amplitude (voltage) if only implied (i.e. perhaps they are variable DC sources?)A circuit has input voltage V1 and V2. Design the circuit so that the output voltage is V0 = 10∫V1dt -5V2.
The input impedance of both voltage sources should be ≥ 100kΩ. Assume ideal op amp.