Hi,
First, I want to thank you people for the help.
1. Define a function f by setting f(x)=1 if x=1/m for some positive integer m (e.g. f(1)=1, f(1/2)=1, f(1/3)=1,...) and f(x)=0 otherwise. Show that f is integrable on the interval [0,1] by proving that the limit of the lower Riemann sums...