初中简单操作百科及答案

=(1-1/2)(1+1/2)(1-1/3)(1+1/3) .(1-1/2004)(1+1/2004)(1-1/2005)(1+1/2005)

=(1-1/2)(1-1/3).(1-1/2004)(1-1/2005)(1+1/2)(1+1/3) .(1+1/2004)(1+1/2005)

=1/2×2/3×3/4×.2003/20004×20004/2005×3/2×4/3×.×20005/20004×20006/2005