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#1




Causal LTI system question
Here is a question in the textbook that I have no idea how to do:
Consider a causal LTI system with input x[n] and output y[n] y[n] = 0.25 y[n1] + x[n] Determine y[n] if x[n] = UnitImpulse[n1] The solution starts off with "Since the system is causal, y[n] = 0 for n < 1".... but I don't understand how they are able to say that...Why do they say this? 
#2




A causal system will not be able to generate an output before an input is supplied. Since the shifted unit step input is zero for all values before n=1, the output of the causal system is also necessarily zero for all n less than 1.

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causal, lti, question 
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