1. The problem statement, all variables and given/known data http://gyazo.com/d875970963124b7d4a64acc887f168fa 3. The attempt at a solution I dont understand the part where they take the derivative of a diff eq to find the higher derivatives can somebody explain it? Mainly the answer where they get y''=(y'')'=(1-y^2)'=-2yy'(this part) y^(4)=(y''')'=(-2yy')'=-2y'y'-2yy"(huh?)=-2(y')^2-2yy''