Which of the following sets forms a fundamental set of solutions of the linear homogeneous differential equation 9t^2y'' + 9ty' - y = 0, t > 0.
Select one:
y1 = 3t^(1/3), y2 = 3t^(-1/3)
y1 = t^3, y2 = t^(-3)
none of the given answers is true
y1 = 3t^(1/3), y2 = t
y1 = 2t^(1/3), y2 = 3t^(1/3)