Quick Recap — Linear Differential Equations

  • Standard form: dydx+P(x)y=Q(x)\tfrac{dy}{dx}+P(x)y=Q(x).
  • Integrating factor: IF=ePdx\mathrm{IF}=e^{\int P\,dx}.
  • Solution: yIF=QIFdx+Cy\cdot\mathrm{IF}=\displaystyle\int Q\cdot\mathrm{IF}\,dx+C.
  • If Q=0Q=0, the equation reduces to y=CePdxy=Ce^{-\int P\,dx}.