- #1

jaus tail

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## Homework Statement

Is the system: y(t) = x(-t) time variant or time invariant?

## Homework Equations

Condition for time invariant:

1) Apply delay to input and check output as Y1

2) Apply input to system without delay and apply delay to output and name it as Y2

If Y1 = Y2, system is Time invariant.

## The Attempt at a Solution

We have y(t) = x(-t)

So I tried with example:

T -3 -2 -1 0 1 2 3

x(t) 1 2 3 4 5 6 7

y(t) 7 6 5 4 3 2 1

At time t = 2

First apply delay to input.

Delay of 1

So time becomes 1

x(1) = 5

y(1) = x(-1) = 3-----equation 1

Now at time t = 2

Apply this to system

y(2) = x(-2) = 2

Apply delay of 1

y(1) = 3-----equation 2

Equation 1 and equation 2 are same.

So this is time invariant.

Book says it's time variant equation.

How?

If I go by red line (first delay and then system)

or if I go by blue line (first system and then delay) I get same answer,

so how is this time variant?

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