DefinitionIntegrating factors are special functions used to make solving differential equations of the following type, dydx+P(x)y=Q(x) easier. Multiplying through by an integrating factor, typically a function e∫P(x)dx that is chosen so that it has the property of turning the left side of the equation into a derivative of a product of functions (a complementary property also held by the right side of the equation), allows the differential equation to be easily integrated. This process changes given equation to simple form and hence solve this equation. For instance, for the differential equation dy/dx +y = ex, the integrating factor is ex so that e∫ 1dx=ex. If we multiply through by ex, we get exdy/dx+exy=e2x so that d/dx(exy)=e2x. Taking the integral of both sides, we have exy=∫e2xdx.