what is bi quadratic

In mathematics, aquartic function, is a function of the form

whereais nonzero, which is defined by a polynomial of degree four, calledquartic polynomial.

Sometimes the termbiquadraticis used instead ofquartic, but, usually,biquadratic functionrefers to a quadratic function of a square (or, equivalently, to the function defined by a quartic polynomial without terms of odd degree), having the form