i need help with this homework that is on electrical engineering Signals and Systems

EE 348, Signals and Systems

Homework 3, Due:02/11/2016, 5:00 pm

February 8, 2016

1. For each of the following continuous time systems,determine whether it is stable/unstable, memoryless/with memory, causal/non-causal, linear/non- linear and time-invariant/time-varying. Justify your answer. [60 points]

(a) y(t) = x2(t).

(b) y(t) = cos(4πt)x(t).

(c) y(t) = cos(4πt + x(t)).

(d) y(t) = t∫ −∞

x(τ)dτ.

(e) y(t) = x(−t). (f) y(t) = x(t − 2) + x(1 − t).

2. Find the expression for [40 points]

(a) y(t) = u(t) ∗ 3u(t) (b) y(t) = tu(t) ∗ u(t).

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