| 2010(1999+2009)x | 
| 1999×2010×2009 | 
| 2011×2010×2009+2×1999×2010-1999×2009 | 
| 1999×2010×2009 | 
整理得:(2010×2009+1999)x=2011×2010×2009+1999(4020-2009),
即(2010×2009+1999)x=2011×(2010×2009+1999),
解得:x=2011.
| x-2011 | 
| 1999 | 
| 1-x | 
| 2010 | 
| x-2 | 
| 2009 | 
| 2010(1999+2009)x | 
| 1999×2010×2009 | 
| 2011×2010×2009+2×1999×2010-1999×2009 | 
| 1999×2010×2009 |