※ 引述《windind (有人是志光的会员吗？)》之铭言： : 在高三自然组数学中有提到 : 有心锥线跟无心锥线的退化 : 所以想请问大家要怎麽跟学生讲解「退化」这个观念呢？ : 我知道圆形退化的图形有点跟没有图形 : 但是为什麽是叫做退化呢？ : 觉得这个观念有点难解释 : 所以想请问大家都怎麽解释这个观念的呢？ : 谢谢大家 http://mathworld.wolfram.com/Degenerate.html 　　A limiting case in which a class of object changes its nature so as to belong to another, usually simpler, class. For example, the point is a degenerate case of the circle as the radius approaches 0, and the circle is a degenerate form of an ellipse as the eccentricity approaches 0. 　　Another example is the two identical roots of the second-order polynomial . Since the roots of an th degree polynomial are usually distinct, roots which coincide are said to be degenerate. Degenerate cases often require special treatment in numerical and analytical solutions. For example, a simple search for both roots of the above equation would find only a single one: 1. 　　The word degenerate also has several very specific and technical meanings in different branches of mathematics. 　　简单的以二次曲线来讲，当我们把其中一个变因变成一个特定的数值 使得这个图形变成另一种比较简单的类型的时候，就说这个变化的过程是 退化。 　　所以说椭圆退化成圆，抛物线退化成直线…ＯＯ退化成ＸＸ因为ＹＹ 的条件逼近於ＺＺ。 　　退化的临界值也是一般讨论的重点，而临界值在退化的意义解释上也 因情况而异。 -- 我怎麽半夜了还看家教板 冏|| -- ◢██◣ ◢██◣ ◢██◣█ ◢◣ ε-δ method █ █ █ █ █◤◥██ ◤◥ █◢█◣ ██◢◢ ◣ ██◢◢██◣ꤠ█ ◢█◣█ ◢█◣██ ◣██◣ ㊣ █ ██ █ █ ▊ █ ██◤ █ ▆◤ █ █ █ █ █ █◥▃▃ ◥█ ◣ 红 █ ◥██◤█ ▊ ◥██◤◤ ◥▆▆◤ █ █ █ █ █ █◣ ◥██ 鸟 了解自己比认识别人重要，对自己负责才能爱别人，没有更多的事情◥█ e◤ ψLank --

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