Identify type of equation: Identify the type of differential equation.This is a first-order linear differential equation.
Rewrite in standard form: Rewrite the equation in standard form. dxdy+yx=−x3 can be written as dxdy+xy=−x3.
Find integrating factor: Find the integrating factor, μ(x).μ(x)=e(∫xdx)=e2x2.
Multiply by integrating factor: Multiply the entire differential equation by the integrating factor.e2x2⋅dxdy+e2x2⋅xy=−x3⋅e2x2.
Recognize derivative of product: Recognize the left side of the equation as the derivative of a product. dxd[y⋅e(x2/2)]=−x3⋅e(x2/2).
Integrate both sides: Integrate both sides with respect to x.∫dxd[y⋅e(x2/2)]dx=∫−x3⋅e(x2/2)dx.y⋅e(x2/2)=−∫x3⋅e(x2/2)dx+C.
Solve integral: Solve the integral on the right side.This step involves an error in integration; the integral of −x3⋅ex2/2 is not elementary and cannot be expressed in terms of elementary functions.