Question

请帮忙解答，谢谢！

Answer 1

原始=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+........+1/18-1/19+1/19-1/20
=1/5-1/20
=4/20-1/20
=3/20
=20分之3
朋友，请采纳正确答案，你们只提问，不采纳正确答案，回答都没有劲！！！
朋友，请【采纳答案】，您的采纳是我答题的动力，如果没有明白，请追问。谢谢。

Answer 2

=1/5-1/6+1/6-1/7+1/7-1/8+。。。+1/18-1/19+1/19-1/20
=1/5-1/20
=3/20

Answer 3

上面的已经给出答案了

Answer 4

=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+........+1/18-1/19+1/19-1/20
=1/5-1/20
=4/20-1/20
=3/20

Answer 5

先把分数的乘法变成减法：
=1/5-1/6+1/6-1/7+1/7-1/8+......+1/18-1/19+1/19-1/20
=1/5-1/20
=3/20