1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20等于多少?
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/30 10:40:33
![1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20等于多少?](/uploads/image/z/335520-0-0.jpg?t=1%2F1%2A2%2B1%2F2%2A3%2B1%2F3%2A4%2B1%2F4%2A5%2B.%2B1%2F19%2A20%E7%AD%89%E4%BA%8E%E5%A4%9A%E5%B0%91%3F)
1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20等于多少?
1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20等于多少?
1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20等于多少?
1/1*2+1/2*3+1/3*4+1/4*5+.+1/19*20
=1-1/2+1/2-1/3+……+1/19-1/20
=1-1/20
=19/20