# signal and system

Discussion in 'Homework Help' started by micro1, Apr 5, 2015.

1. ### micro1 Thread Starter Member

Feb 22, 2015
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0
hello every one

signal and system

properties of system Linearity

I did my problem

you can check my solution it is true?

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Last edited: Apr 6, 2015
2. ### WBahn Moderator

Mar 31, 2012
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5,758
I'm assuming that you mean

y[n] = x²[n-1]

If so, then this says that the present value of y is equal to the square of the previous value of x.

This is NOT the same as

y[n] = x²[n] - x²

This says that the current value of y is equal to the square of the current value of x minus the square of something that is not even at a defined time.

3. ### micro1 Thread Starter Member

Feb 22, 2015
63
0
if change the equation to

X1 = X1 [ Xn - X ]

X2 = X2 [ Xn -X ]

X3 = X1 +X2 ==> ( X1 [ Xn - X ] + X2 [ Xn -X ] )

X3 = X3 [ Xn -X ]

X3 = X1 +X2 ( linearity)

4. ### WBahn Moderator

Mar 31, 2012
20,237
5,758
So, if you had the continuous time signal

y(t) = x²(t-1sec)

are you saying that you would rewrite this as

y(t) = x(x·t - x·1sec)

Does that make ANY sense whatsoever?

Last edited: Apr 6, 2015
5. ### micro1 Thread Starter Member

Feb 22, 2015
63
0
ok, now is linearity and nonlinearity?

6. ### djsfantasi AAC Fanatic!

Apr 11, 2010
3,496
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"I don't even know what I am talking about!" - Bud Abbott

...meaning I have the same doubts as WBahn

Last edited: Apr 6, 2015
7. ### WBahn Moderator

Mar 31, 2012
20,237
5,758
There is no point moving on to the distinction of linear and non-linear systems until you are clear on what a system is to begin with.