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In the circuit shown in the given figure $\mathrm{N}$ is a finite gain amplifier with a gain of $k$, a very large input impedance, and a very low output impedance. The input impedance of the feedback amplifier with the feedback impedance $\mathrm{Z}$ connected as shown will be

1. $\mathrm{Z}\left(1-\frac{1}{k}\right)$
2. $Z(1-k)$
3. $\frac{\mathrm{Z}}{(k-1)}$
4. $\frac{Z}{(1-k)}$