largedarryl on 07 November 2008
Thanks for the refresher Lingyis, it's funny how quickly the basic calculus leaves your brain when you finish school, but I'm pretty sure my second attempt is the same as yours (only yours is more of a proof).
EDIT: Are you sure |cos(8x)| does not appear in the denominator? That is the only way I can see the df/dx working out to a non-real value (divide by 0).
