Fermions in harmonic oscillator potential

Two identical, non-interacting spin-1/2 fermions are placed in the 1-D harmonic potential

V(x) = (1/2)mω2x2,

Where m is the mass of the fermion and ω is its angular frequency.

a. Find the energies of the ground and first excited states of this two-fermion system.  Express the eigenstates corresponding to these two energy levels in terms of harmonic oscillator wave functions and the singlet and triplet spin states.
b. Calculate the square of the separation of the two fermions,
<(x1-x2)2>=<(x12+x22-2x1x2)>
for the lowest energy state of the two-fermion system.
c. Repeat the calculations for the first excited states.