The impulse response of a system is h(t) = t u(t). For an input u(t − 1), the output is
(a) \frac{t^2}{2} u(t) (b) \frac{t(t-1)}{2} u(t-1)
(c) \frac{(t-1)^2}{2} u(t-1) (d) \frac{t^2-1}{2} u(t-1)
Given that impulse response is h(t) = tu(t). For input response u(t-1),
\begin{aligned} \delta(t) & \rightarrow t a(t) \\ u(t) & \rightarrow t u(t) d t=u \\ \int_0^t t d t & =\frac{t^2}{2} u(t) \\ u(t-1) & \rightarrow \frac{(t-1)^2}{2} u(t-1) \end{aligned}