% MH-20210116

# 原解

~~~
1 * 5 = 5

2 * 4 = 8

3 * 3 = 9
~~~

# 扩展

~~~
6 = 3 + 3 = 3 + 3 + 1 - 1 = 3 + 1 + 3 - 1 = (3 + 1) + (3 - 1)

(3 + 1) * (3 - 1) = 3 * 3 + 3 * (-1) + 1 * 3 + 1 * (-1) = 3 * 3 + 1 * (-1) = 3 * 3 - 1 ^ 2 = 3 ^ 2 - 1 ^ 2

3 ^ 2 > 3 ^ 2 - 1 ^ 2
~~~

