1. ## Decreasing function integral

Hi, everybody! I'm just taking my first integral calculus course, so I'm having a little trouble with some things. I hope you can guide me to prove this:

"If f is a decreasing function on [a, b], prove that f is integrable."

Thanks!

2. ## Re: Decreasing function integral

Originally Posted by Cesc1
"If f is a decreasing function on [a, b], prove that f is integrable."
A decreasing function on $[a,b]$ then the set of discontinuities is countable.
That means the function is Riemann integrable.