1/2×4+1/6×8+...+1/2006×2008+1/4×6+1/8×10+...+1/2004×2006
=1/2×4+1/4×6+1/6×8+1/8×10+...+1/2004×2006+1/2006×2008
=1/2[(1/2-1/4)+(1/4-1/6)+(1/6-1/8)+……+ (1/2006-1/2008)]
=1/2(1/2-1/2008)
=1/2(1004/2008-1/2008)
=1/2*1003/2008
=1003/4016
1/2×4+1/6×8+...+1/2006×2008+1/4×6+1/8×10+...+1/2004×2006
=1/2×4+1/4×6+1/6×8+1/8×10+...+1/2004×2006+1/2006×2008
=1/2[(1/2-1/4)+(1/4-1/6)+(1/6-1/8)+……+ (1/2006-1/2008)]
=1/2(1/2-1/2008)
=1/2(1004/2008-1/2008)
=1/2*1003/2008
=1003/4016