摘要
假设在xy-平面上给定了一条曲线（图1），方程φ（z，y）=0称为一条曲线的隐式方程，如果这条曲线上的任一点的坐标（z，y）满足它，并且满足这个方程妒（z，y）=0的任意一对数z，Y是这条曲线上一个点的坐标．显然，一条曲线由它的方程所确定，因而，我们可以说用它的方程表示的曲线．
Let there be given a curve on the xy-plane （Fig. 1）. The equation φ（x,y）=0 is called the equation of a curve in the implicit form if it is satisfied by the coordinates（x,y） of any point of this curve and any pair of numbers x, y, satisfying the equation φ （x, y） = 0 represents the coordinates of a point on the curve. As is obvious, a curve is defined by its equation , therefore we may speak of reoresenting a curve by its eauation.
