Solution
= Solution
Integrating $F=-kx$ gives $V=kx^2/2$ up to a constant. Thus $\boxed{-\hbar^2\phi''/(2m)+m\omega^2x^2\phi/2=E\phi}$, with $\omega=\sqrt{k/m}$. The potential is a symmetric upward parabola and tends to infinity in both directions; normalizable states decay at large $|x|$.