1. The problem statement, all variables and given/known data http://prntscr.com/czcn8h 2. Relevant equations n/a 3. The attempt at a solution I know that if you derive x^2sin(1/x) you get -cos(1/x) + sin(1/x)(2x). But what do I do from here? If I use the limit definition, i'll end up getting something like h(sin(1/h)) after evaluating. I still don't understand how the limit definition will show that this exists.