The following question is right from the book:
Show that
$$ H(x-x_i) = \int_{-\infty}^x \delta(x_0-x_i)dx_0\, $$
satisfies $$ H(x-x_i) \equiv \begin{cases} 0 & x < x_i \\ 1 & x > x_i; \end{cases} $$
$\delta(\cdot)$ being the Dirac $\delta$ function and $H$ being the Heaviside unit step function.
Thing is, I don't know where to start on this question. How do you prove such a question?
Thanks in advance.