[900forst]

=0,5[(1-h)(1-h)²-3(1-h)² +(1+h)(1+h)²-3(1+h)²]
=0,5[(1-h)|(1-h)²-3(1-h)| +(1+h)|(1+h)²-3(1+h)|]
=0,5[(1-h)|1-2h+h²-3+3h| +(1+h)|1+2h+h²-3-3h|]
=0,5[(1-h)|h²+h-2| +(1+h)|h²-h-2|]
=0,5[h²+h-2-h³-h²+2h+h²-h-2+h³-h²-2h]
=0,5[-4]
=-2

Hoffe ich habe mich zwischendurch nicht vertan