Question

A transfer function has two zeroes at infinity. Then the relation between the numerator(N) and the denominator degree(M) of the transfer function is:

(a) N=M+2

(b) N=M-2

(c) N=M+1

(d) N=M-1

The question was posed to me during an interview.

I'm obligated to ask this question of Transfer Functions topic in chapter Mathematical Models of Physical Systems of Control Systems

Answer 1

Right choice is (b) N=M-2

To explain: Zeroes at infinity implies two poles at origin hence the type of the system is two and degree of denominator is M=N+2.