Đáp án:
`4/(2xx4)+4/(4xx6)+4/(6xx8)+...+4/(2008xx2010)`
`=2xx(2/(2xx4)+2/(4xx6)+2/(6xx8)+...+2/(2008xx2010))`
`=2xx((4-2)/(2xx4)+(6-4)/(4xx6)+(8-6)/(6xx8)+...+(2010-2008)/(2008xx2010))`
`=2xx(1/2-1/4+1/4-1/6+1/6-1/8+...+1/2008-1/2010)`
`=2xx[1/2+(-1/4+1/4)+(-1/6+1/6)+...+(-1/2008+1/2008)-1/2010]`
`=2xx(1/2-1/2010)`
`=2xx502/1005`
`=1004/1005`