dy/dx = (y-3) e^(cos(xy))

y(1)=1

prove that y(x) < 3 for all x for all y that are defined.

To be honest, I tried a few things but realized I didn't know where to start. I can show that the limit of the slope from neg. infinity to infinity is zero which means 3 is an asymptote but I had no idea how to show this. Ideas?