Solution EDSSM
y0 = u(x) + u(x)

y0 = 

 = 0
1 Solution Double r
y0 = (+x) erx

 > 0
2 Solutions r1 et r2
y0 = er1x + er2x

 < 0
2 Solutions complexes conjuguées
y0 = eAx (cos(Bx)+sin(Bx))

2nd ORDRE