 If we look at the formula_5-page of the spectral sequence
we can see immediately that the only potentially non-trivial differentials are
It turns out that these differentials vanish in both cases, hence formula_50.In the first case, since formula_51 is trivial for formula_52 we have the first set of differentials are zero.The second set are trivial because formula_53 sends formula_54 the identification formula_55 shows the differential is trivial.