falls die Aufgabe so lautet:
1/(t-1) - 5/(1+t) + (7t-9)/(t^2-1) - 5/(1-t)
der Hauptnenner lautet (t+1)(t-1)
=1/(t-1) - 5/(1+t) + (7t-9)/(t^2-1) + 5/(t-1)
= (t+1 -5(t-1) +7t -9 +5(t+1)) / ((t+1)(t-1))
=(t+1 -5t +5 +7t -9 +5t+5) / ((t+1)(t-1))
= (8t +2)/(t^2 -1)