FOR TIME INVARIANT SYSTEM
[ tex ] x_1(t)------>y_1(t) [ \tex ]
[ tex ] x_2(t)= x_1(t-T) [\tex] ---keep this equation same
[tex]x_2(t)------>y_2(t) [\tex]<br />
[tex]y_2(t)=y_1(t-T) [\tex]<br />
<br />
If all these conditions are true for that function then YES its TIME INVARIANT else its TIME VARYING. So if you put Y(t)=X(2t) here and you will see that eqn (3) is not equal to eqn(4). So its TIME VARYING.[/tex][/tex]