来自《耶鲁大学开放课程：基础物理 第4集 第4集》

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  involving the second derivative or the first derivative
  可以包括二阶导数 或者一阶导数
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  or the fourteenth derivative, whatever it is.
  或者十四阶导数 无论多少阶都行
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  You are supposed to find out what x(t) is, given this information.
  你需要根据这个条件求出 x(t)
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  So, one thing is,
  有一种方法是
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  you can go to the Math Department and say,
  你可以到数学系去说
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  "Hey look, I got this equation, what's the solution?"
  "看 我这儿有个方程 解是多少"
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  and they will tell you.
  他们会告诉你答案的
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  Now, sometimes we have to do our own work
  有时候我们得自己来做
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  and we can solve this equation by guessing.
  我们可以用猜的方法来解这个方程
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  In fact, the only way to solve a differential equation
  实际上 解微分方程的唯一方法
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  is by guessing the answer;
  就是去猜答案
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  there is no other way.
  没有其它办法