[微積] 證明題

[monemo13 (李孟李孟)]

題目如下：

Let f(x+y) = f(x)+f(y) for all x and y in R.
Prove that there is a number m such that f(t)= mt for all rational number t.

HINT: First decide what m has to be.
      Then proceed in steps, starting with f(0)= 0 , f(p)= mp for p in N,
      f(1/p)= m/p, and so on.

像這樣的證明題...我該如何開頭如何結尾呢?

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