Rohrdorf was first mentioned in 788 in the so called notitia arnonis.
Settlements have been proofed also in prehistoric time.
See also:
http://www.rohrdorf.de
... square[?]. <math>ax^2+bx+c=0</math> Dividing our quadratic equation by a, we have <math> x^2 + \left( \frac{b}{a} \right) x + ...