The differential equation is second order, homogeneous and has constant coefficients. We can therefore use the auxiliary equation: 4 2 – 19 – 30 = 0 It factorises: ( – 6) (4 + 5) = 0
The two roots of the auxiliary equation are
6
and
–
5
4
The general solution is
y = Ae6 x + Be – 5/4 x where A and B are arbitrary constants.