Ta có:
`A = 2008 . 2009 + 2010`
`= 2008 . 2009 + 2008 + 2`
`= 2008 . (2009 + 1) + 2`
`= 2008 . 2010 + 2`
`B = 2009 . 2010 - 2008`
`= 2009 . 2010 - (2010 - 2)`
`= 2009 . 2010 - 2010 + 2`
`= 2010 . (2009 - 1) + 2`
`= 2010 . 2008 + 2`
Vì `2008 . 2010 + 2 = 2010 . 2008 + 2`
`⇒ A = B`.