# Quod Erat Demonstrandum

## 2009/04/15

### 純數生活例子（無聊篇）

Filed under: Pure Mathematics — johnmayhk @ 8:09 上午

f(紅) = 黃
f(黃) = 綠 – – – (1)
f(綠) = 黃
f(黃) = 紅 – – – (2)

f(紅) = 紅黃
f(紅黃) = 綠
f(綠) = 黃
f(黃) = 紅

1997 Paper 2 Q.8
…the use of strange notations like $f'_{+}$ and $f'_{-}$ without defining them properly…

1998 Paper 2 Q.9
…It was interesting to see some candidates using the “double factorial" notation in expressing $I_{2n}, I_{2n + 1}$, a notation used only in books published in the Mainland.