Question

Which of the following systems is memoryless?

(a) y(t) = x(2t) + x(t)

(b) y(t) = x(t) + 2x(t)

(c) y(t) = -x(t) + x(1-t)

(d) y(t) = x(t) + 2x(t+2)

This question was posed to me by my school principal while I was bunking the class.

Origin of the question is Properties of Systems in section Signals and Systems Basics of Signals and Systems

Answer 1

Correct choice is (b) y(t) = x(t) + 2x(t)

To explain: A system possessing no memory has its output depending upon the input at the same time instant, which is prevalent only in option b.