Question

Which of the following systems is memory less?

(a) y(t) = 2x(t) + ^d⁄dx x(t)

(b) y(t) = 2x^2 (t) + ^d⁄dx x(t)

(c) y(t) = ∫x(t)dt

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

This question was posed to me at a job interview.

This interesting question is from Properties of Systems topic in chapter Signals and Systems Basics of Signals and Systems

Answer 1

Right choice is (d) y(t) = 2x^2 (t)

The explanation: A differentiator or integrator maybe realized with capacitors and inductors and cannot be realized using resistors. Hence differentiators and integrators can be considered as systems with memory.