1/2+1/6+1/12+1/20=
来源：学生作业帮助网 编辑：六六作业网 时间：2024/12/23 07:06:03
1/2+1/6+1/12+1/20=1/2+1/6+1/12+1/20=1/2+1/6+1/12+1/20=4/51/2+1/6+1/12+1/20=1-1/2+1/2-1/3+1/3-1/4+1/4
1/2+1/6+1/12+1/20=
1/2+1/6+1/12+1/20=
1/2+1/6+1/12+1/20=
4/5
1/2+1/6+1/12+1/20
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5
=1-1/5=4/5
(30+10+5+3)/60=4/5
1/2+1/6+1/12+1/20=
1/1*2+1/2*3+1/3*4+1/4*5
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5
=1-1/5
=4/5
希望你能看懂！
7/15
1/2+1/6+1/12+1/20
=（1-1/2）+（1/2-1/3）+（1/3-1/4）+（1/4-1/5）
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5
=1-1/5
=4/5
(30+10+5+3)/60=4/5 =0.8
4/5
1-1/5=4/5