1. The problem statement, all variables and given/known data I have to determine the 2nd,3rd and 4th derivative at 0. So ψ''(0) The equation is y'' + sin(x)y' + cos(x)y = 0 A know solution is y = ψ(x). The intial conditions are y(0) = 0 , y'(0) = 1 2. Relevant equations 3. The attempt at a solution I know this is a 2nd order differential equation. However I don't know what to do. I can't use characteristic equations in this case. And if I juts take the 1st and 2nd derivative here and plug them I won't attain anything.