Find the ODE such that 1, x, cos(√ 2x),sin(√ 2x) is a fundamental set of solutions.
a) y'' - 2y' + 2y = 0
b) y'' + 2y' - 2y = 0
c) y'' + 2y' + 2y = 0
d) y'' - 2y' - 2y = 0