quadratic equation
which is established by completing the square. The term b 2 − 4ac is known as the discriminant. The equation has two distinct real roots, a repeated real root, or two complex conjugate roots, depending on whether the discriminant is positive, zero, or negative respectively.
If α and β are the roots of the quadratic equation ax 2 + bx + c = 0, then α + β = −b/a and αβ = c/a. (See Viète's formulae.) The quadratic formula is still valid over other fields provided that the discriminant has a square root in the field.
- approximation theory
- a priori
- a priori
- apse
- Apéry's constant
- Arabic numeral
- arbitrarily large/small
- arbitrary
- arc
- arc
- arc-connected
- arccos
- arccosh
- Archimedean property
- Archimedean solid
- Archimedean spiral
- Archimedes
- Archimedes' constant
- Archimedes' method
- arc length
- are
- area
- area of a surface of revolution
- area under a curve
- arg