# Dictionary Definition

biquadratic adj : of or relating to the fourth
power

### Noun

2 an equation of the fourth degree [syn: biquadratic
equation]

3 a polynomial of the fourth degree [syn:
biquadratic polynomial, quartic
polynomial]

# User Contributed Dictionary

## English

### Adjective

- Of a polynomial expression, involving only the second and fourth powers of a variable, as x4 + 3x2 + 2. Sometimes extended to any expression involving the fourth power of variable (but no higher powers), as x4 − 4x3 + 3x2 − x + 1.

# Extensive Definition

A quartic function is a function
of the form

- f(x)=ax^4+bx^3+cx^2+dx+e \,

with nonzero a; or in other words, a polynomial function with a
degree of four. Such a function is sometimes called a biquadratic
function, but the latter term can occasionally also refer to a
quadratic function of a square, having the form

- ax^4+bx^2+c \,,

or a product of two quadratic factors, having the
form

- (ax^2+bx+c)(dy^2+ey+f) \,.

The derivative of a quartic
function is a cubic
function.

On finding the roots, see Quartic
equation.

biquadratic in French: Courbe quartique

biquadratic in Polish: Wielomian stopnia
czwartego