The differential equation is second order, homogeneous and has constant coefficients. We can therefore use the auxiliary equation: 2 – 11 – 26 = 0 It factorises: ( + 2) ( – 13) = 0
The two roots of the auxiliary equation are
–2
and
13
The general solution is
p = Ae – 2 x + Be13 x where A and B are arbitrary constants.