The zither is a musical string instrument, mainly used in folk music. The strings are stretched across the length of the soundbox and the instrument does not have a neck.
... both sides, we get
<math>x=\frac{-b}{2a}\pm\frac{\sqrt{b^2-4ac}}{2a}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}.</math>
Generalizations
The formula and its ...