Why is the unit step function in the end is written as $u(t-t_1-t_0)$ instead of just $u(t-t_0)$?

220 Views Asked by At

So this is basically about signals and systems and how to compute the output of the system using only the impulse response and the given input signal- where x(t) is the input signal and h(t) is the impulse response. the output y(t) is simply the convolution of the impulse response and input. At first it's all good as convolution is applied. I get how the limits of integration are changed accordingly because of the two unit step functions. and then I'm stuck.

f(T) in the picture below is supposed to be x(t). thanks in advance