1/(5·d^2 - 5·e^2) + 1/(10·d + 10·e) - 1/(2·e - 2·d)
= 1/(5·(d^2 - e^2)) + 1/(10·(d + e)) - 1/(2·(e - d))
= 1/(5·(d + e)·(d - e)) + 1/(10·(d + e)) + 1/(2·(d - e))
Auf einen Hauptnenner bringen
= 2/(10·(d + e)·(d - e)) + (d - e)/(10·(d + e)·(d - e)) + 5·(d + e)/(10·(d + e)·(d - e))
= (2 + (d - e) + 5·(d + e))/(10·(d + e)·(d - e))
= (6·d + 4·e + 2)/(10·(d + e)·(d - e))
= (3·d + 2·e + 1)/(5·(d + e)·(d - e))