(a) An op-amp with an open-loop gain of \(A_{o d}=7 \times 10^{3}\) is to be used in an inverting op-amp circuit. Let \(R_{2}=100 \mathrm{k} \Omega\) and \(R_{1}=10 \mathrm{k} \Omega\). If the output voltage is \(v_{O}=7 \mathrm{~V}\), determine the input voltage and the voltage at the inverting terminal of the op-amp.

(b) If the output voltage is \(v_{O}=-5 \mathrm{~V}\) and the voltage at the inverting terminal of the op-amp is \(0.2 \mathrm{mV}\), what is the input voltage and the value of \(A_{o d}\) ?