$1.$ Consider a system with input x$($t$),$ output y$($t$),$ and unit impulse response, h$($t$)=$ e $3$tu$($t$).$ If this system is excited by a rectangular pulse x$($t$)=$ u$($t $+3)$ u$($t $3).$ Find an expression for Y $($$).[$Hint: write the input x$($t$)$ in terms of a rect$-$function to use the FT pairs we learned.$]$