Tính: A = 1/1004×2006+1/1005×2005+1/1006×2004+....+1/2006×1004

Tính  A/B:
A=1/1004×2006+1/1005×2005+1/1006×2004+....+1/2006×1004
B=1/1×2+1/3×4+1/5×6+...+1/2005×2006