Question

Which of the following systems is linear?

(a) y(t) = sin(x(t))

(b) y(t) = log(x(t))

(c) y(t) = cos(x(t))

(d) y(t) = dx(t)/dt

I have been asked this question in quiz.

My enquiry is from Properties of Systems in portion Signals and Systems Basics of Signals and Systems

Answer 1

Correct answer is (d) y(t) = dx(t)/dt

For explanation: Only d satisfies both the scaling and the additivity properties.