i wanna ask from expert. Not by using contradiction method, Assuming f(x)is continuous function.Iff(x)is monotonic and af(x)dxis convergent, then limxf(x)=0.I wanted to prove this statement rigoruously. (haveto split it into cases based on monotonicity types .) you need to show for every epicilone, there exist n>0, for every x belongs toR,x>n implies |f(x)|< epicilone