1. The problem statement, all variables and given/known data u'''-8u''+2u'-3u=0 2. Relevant equations 3. The attempt at a solution So I let: x1 = u then x1' = u' x2 = u' then x1' = x2 and x2' = u'' x3 = u'' then x2' = x3 and x3' = u''' I have only done these problems with second order equations, so I don't understand which values I am supposed to plug back into the original equation. Any help is appreciated! Thanks!