First-Order Differential Equations

First-Order Differential Equation - Variants

1st-Order Separable DE

𝑃(𝑦, 𝑑𝑦) = 𝑄(π‘₯, 𝑑π‘₯)Β # 𝑒.𝑔. 𝑦’ = π‘₯/𝑦

1st-Order Homogenous DE

𝑦’ = 𝐹(𝑦/π‘₯)Β # 𝑒.𝑔. 𝑦’ = (π‘₯2Β + 𝑦2)/π‘₯𝑦

1st-Order Bernoulli DE

𝑦’ + 𝑃(π‘₯)𝑦 = 𝑄(π‘₯)𝑦𝑛 # π‘›βˆ‰{0,1}

1st-Order Exact DE

𝑃(π‘₯)𝑦 + 𝑄(π‘₯)𝑦’ and there exist a function πœ‘(π‘₯,𝑦) such that (π›Ώπœ‘/𝛿π‘₯) = 𝑃(π‘₯)Β and (π›Ώπœ‘/𝛿𝑦) = 𝑄(π‘₯)

1st-Order Linear DE

𝑓(π‘₯) = 𝑃(π‘₯)𝑦 + 𝑄(π‘₯)𝑦’

  • 1st-Order Linear Homogenous DE:Β 0Β = 𝑃(π‘₯)𝑦 + 𝑄(π‘₯)𝑦’
  • 1st-Order Linear Constant Coefficient DE: 𝑓(π‘₯) = 𝑝𝑦 + π‘žπ‘¦β€™
  • 1st-Order Linear Constant Coefficient Homogenous DE:Β 0Β = 𝑝𝑦 + π‘žπ‘¦β€˜

First-Order Differential Equation - Methods in Solving the DE

Method of Separating Variables

solves first-order separable differential equations

Method of Integrating Factor

solves first-order non-separable linear differential equations

Method for Homogenous DE

solves first-order homogenous non-separable non-linear differential equations

Solving Exact DE

solves first-order exact differential equations

First-Order Differential Equation - Example