In mathematics, an implicit equation is a relation of the form R(x1,…,xn)=0{\displaystyle R(x_{1},\ldots ,x_{n})=0}, where R{\displaystyle R} is a function of several variables (often a polynomial). For example, the implicit equation of the unit circle is x2+y2−1=0{\displaystyle x^{2}+y^{2}-1=0}.