1. The problem statement, all variables and given/known data Solve for A: dA/ds = -k s 2. Relevant equations See problem statement 3. The attempt at a solution I switched the equation around: dA= -k s ds Integrated: A= -(k/2) (s^2+c) Apparently, that is wrong and I see that the answer should be: A= -(k/2) (s^2-b^2) My question is: Why must the constant of integration subtract from s^2? Why couldn't it add to it?