$$ \text { The current } I \text { in the given network is } $$

For a 2-port network consisting of an ideal lossless transformer, the parameter $S_{21}$ (rounded off to two decimal places) for a reference impedance of $10 \Omega$ is $\_\_\_\_$ .

The output $y[n]$ of a discrete - time system for an input $x[n]$ is

$$ y[n]=\max\limits_{-\infty \leq k \leq n}|x[k]| $$

The unit impulse response of the system is

Which one of the following pole-zero plots corresponds to the transfer function of an LTI system characterized by the input-output difference equation given below?

$$ y[n]=\sum_{k=0}^3(-1)^k x[n-k] $$