Question

The coefficients of numerator polynomial and the denominator polynomial in a transfer function must be?

(a) real

(b) complex

(c) at least one real coefficient

(d) at least one complex coefficient

This question was posed to me in a job interview.

Question is from Properties of Transfer Functions in section S-Domain Analysis of Network Theory

Answer 1

The correct option is (a) real

The explanation is: The coefficients of P(s), the numerator polynomial and of Q(s), the denominator polynomial in a transfer function must be real. Therefore all poles and zeros if complex must occur in conjugate pairs.