An implicit equation is an equation which relates the variables involved. For example, the equation \(x^2+y^2=4\) gives a relationship between \(x\) and \(y\), even though it does not specify \(y\) explicitly in the form \(y=f(x)\).
As this example shows, it may not be possible to convert an implicit equation into an equation of the form \(y=f(x)\) for some function \(f(x)\), as the \(x\) values in the range \(-2<x<2\) each correspond to two values for \(y\).
