Burchard von Zollern[?] was born before 1025 and died in 1061.
Burchard's son was Friedrich von Zollern[?], born before 1055, died 1114/15 .
... are also called the roots of the equation. The formula reads <math> x=\frac{-b \pm \sqrt {b^2-4ac}}{2a} </math> The term b2 – 4ac is called ...