1. The problem statement, all variables and given/known data I'm gonna solve the equation Y'=0 if Y=x*e-0,4x 2. Relevant equations 3. The attempt at a solution I can come as far as to Y'=(1-0,4x)*e-0,4x Where do I go from here? Can i just write (1-0,4x)*e-0,4x=0 ? I can solve the easier kinds of these equations, but this one is the hardest of the ones that I have, and I suspect that something like this will show up on a test in the future, so it would be good if I can solve it. Anyone can help me in the right direction?