1-1/2(1/3-1)(1-1/4)(1/5-1)...(1-1/2004)(1/2005-1)（1-1/2）(1/3-1)(1-1/4)(1/5-1)...(1-1/2004)(1/2005-1)题目拼错了应该是这样的

Question

1-1/2(1/3-1)(1-1/4)(1/5-1)...(1-1/2004)(1/2005-1)
（1-1/2）(1/3-1)(1-1/4)(1/5-1)...(1-1/2004)(1/2005-1)题目拼错了应该是这样的

Answer 1

=（1/2）（-2/3)(3/4)(-4/5).(2003/2004)(-2004/2005)
=1/2005
重要的是要算出有多小个负数
2004/2=1002个负数,所以得数为正数