# How to determine whether a filter is high/low or band pass from the Z transform?

How to solve questions of these kind?

I have tried by replacing $$z=re^{jw}$$ and taking the limits from $$0$$ to $$\infty$$. But I am not sure what $$e^{j\infty}$$ is.

HINT: There's no need to compute the frequency response by evaluating the transfer functions for $$z=e^{j\omega}$$. Just compute the poles and zeros and see where they are. Estimate the effect of the poles and zeros on the frequency response by trying to see how they influence the behavior of the transfer function on the unit circle.