Math basics › Differential equations
First-order linear equations
The form
dy/dx + P(x)y = Q(x). Get it into exactly this shape first, with nothing in front of the dy/dx.
The integrating factor
Multiply everything by μ = e^(∫P dx). The left side then becomes the derivative of μy, by the product rule.
Then integrate
μy = ∫ μQ dx + C, then divide by μ. Divide the C too: it is easy to drop.