2004×2002/2003=(20032-1)/2003=2003-1/2003=2002 20022003
(1/15+2/17)×15×17=17+2×15=17+30=47
1/(1x2)+1/(2x3)+1/(3x4)+……+1/(98x99)+1/(99+100)=1-1/2+1/2-1/3+1/3-1/4+……+1/98-1/99+1+1/99-1/100=1-1/100=99/100
2004×2002/2003=(20032-1)/2003=2003-1/2003=2002 20022003
(1/15+2/17)×15×17=17+2×15=17+30=47
1/(1x2)+1/(2x3)+1/(3x4)+……+1/(98x99)+1/(99+100)=1-1/2+1/2-1/3+1/3-1/4+……+1/98-1/99+1+1/99-1/100=1-1/100=99/100