拉格朗日中值定理及柯西中值定理的证明,通常以洛尔定理作为它的预备定理。证明的关键在于构造一个辅助函数。所见到的各种分析课本都是沿用传统的辅助函数,这个函数的引入,主要是借助于几何直观,不妨归类为几何方法,尽管有几何形象,学生接 The proof of Lagrange’s mean value theorem and Cauchy’s mean value theorem usually takes Loll’s theorem as its preparation theorem. The key to proof is to construct a helper function. The various analysis textbooks that are seen follow traditional auxiliary functions. The introduction of this function is mainly based on geometrical intuition. It may be categorized as a geometric method. Although there are geometric images, students