show that every solution of u”+cosh(x) u=0 vanished infinitely often on (-infinity,0) and also infinitely often on (0, infinity)

show that every solution of u”+cosh(x) u=0 vanished infinitely often on (-infinity,0) and also infinitely often on (0, infinity)

Consider the differential equationConveniently, write this as…… (1)First neglect the coefficients of u and its derivatives and find the fundamental solution asSo,So, the solutions are…