I need help with this proof...
Show that if f: [a,b] $\displaystyle \rightarrow$ R is monotonic (where a, b $\displaystyle \in$ R, a < b) then f is Riemann integrable on [a,b].
Hello.
It might be a useful fact that a monotonic function defined on some closed interval has at most countably many (jump) discontinuities. It seems that in the worst case scenario, you would have to talk about an infinite series of Riemann integrals.
Just throwing some ideas out there. Good luck.