Convolution integral question

1. Jul 10, 2010

nhrock3

cant understand the red arrow transition
i changes the intervals and i cuts half of the arguent inside the integral
i cant see why
?

regarding the interval change
the H function is 1 in a certain interval
so if they change the integrval then its no longer H inside
because we have taken the '1' part of the H
??

regarding the cutting in half the argument inside the integral
i have no idea

2. Jul 10, 2010