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Electronics and Communication Engineering (ECE) : Signals and Systems - Quiz(MCQ)
Which among the following is an invertible system?
A)
y[n] = 0
B)
y[n] = 2x[n]
C)
y(t) = x2(t)
D)
y(t) = dx(t)/dt

Correct Answer : Option (B) :   y[n] = 2x[n]


Explanation : A system is said to be invertible if it’s input can be found out from its output. Implying, if a system has same outputs for several inputs then it is impossible to find the correct input as output is same for many. Therefore, a system is invertible if it gives distinct outputs to distinct inputs. It is non-invertible if it gives same outputs for many inputs.

Option a produces 0 output for any input → Non-invertible
Option b produces different outputs for different inputs and also it’s inverse system is (1/2)y[n] → Invertible
Option c, we get same output for both positive and negative values → Non-invertible
Option d, we get 0 for all constant input values → Non-invertible.

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