For each of the following systems, show whether or not the system is time-invariant.
(a) y(t) = x(t)u(t)
(b) y(t) = |x(t)|
(c) y(t) = x(t)x(2t)
(d) y(t) = ∫₀ᵗ x(τ)e^(-τ)dτ
(e) (dy(t))/(dt) + ty(t) = x(t)
Notes:
• To show that a system has a given property, it should be shown that the property holds for all possible inputs.
• To show that a system does not have a property, giving one counterexample is sufficient.