$7$Tt

$4\mathrm{.}33.$ The input and the output of a stable and causal L TI system are related by the dif$-$

ferential equation

d$2$y$($t$)$

$6$dy$($t$)$

$8()-2()$

$--+--+$ yt$-$

xt

dt$2$

dt

$($a$)$ Find the impulse response of this system.

$($b$)$ What is the response of this system if x$($t$)=$ te$-2$t u$($t$)?$

$($c$)$ Repeat part $($a$)$ for the stable and causal LTI system described by the equation