The common method to quadric surface equation is to get the Normal Component first, and then write out the equation through dotmethod.
求切平面方程的一般方法是先求切平面的法向量(借助偏导),再用点法式写出切平面的方程。
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Basically, whenever the last argument of a method is an array of objects, or a parameter declaration with a triple dot, you can pass multiple parameters to this method.