The following is a list of musical instruments, categorized by how they make sound.
Wind instruments
String instruments
Keyboard instruments
Tuned-reed instruments[?]
Percussion instruments
Voice
Electronic instruments
Other
... 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 the ...