(Tor_n(X, Y) : n-dimensional torsion product of X and Y)

Prove that, for arbitrary short exact sequences B 0 + A +P+X+0, X 0 + B + Y =0 of modules over R with projective modules P and Q, we have Tor,(X, Y) Tor, 2(A, B) for every n > 2 and Tor2(X, Y) - Ker(a B)