한걸음

Problem 1 ~ 3 의 경우에는 전부 Basic Rule 을 이용하는 단순한 문제다. Problem 1. Find the solution. $$ y'' + 5 y ' + 4 y = 10 e^{-3x} $$ 1) Solution of homogeneous ODEs. Let's solve : $ y'' + 5 y ' + 4 y = 0 $ Substitute $ y = e^{\lambda x} $ into homogeneous ODEs, $$ ( \lambda^{2} + 5 \lambda + 4 ) e^{\lambda} = 0 $$ By the characteristic equation, D > 0 , The ODE has 2 real roots. $$ \therefore y_{h} = c_{1} e^{..