1+ 1/2+1/6+1/+1/12+1/20+.+1/90

来源：学生作业帮助网编辑：作业帮时间：2024/05/05 15:38:38

1+ 1/2+1/6+1/+1/12+1/20+.+1/90
1+ 1/2+1/6+1/+1/12+1/20+.+1/90

1+ 1/2+1/6+1/+1/12+1/20+.+1/90
1/2=1-1/2,1/6=1/2-1/3,1/12=1/3-1/4,1/20=1/4-1/5,...1/90=1/9-1/10;
所以原式=1+1-1/2+1/2-1/3+1/3-1/4+1/4-1/5...+1/9-1/10
=1+1-1/10
=19/10

=1+1/1*2+1/2*3+……+1/9*10
=1+(1-1/2)+(1/2-1/3)+……+(1/9-1/10)
=1+1-1/10
=19/10

1/2=1-1/2
1/6=1/(2×3)=1/2-1/3
1/12=1/(3×4)=1/3-1/4
1/20=1/(4×5)=1/4-1/5
......
1/90=1/(9×10)=1/9-1/10
所以
1+1/2+1/6+1/12+1/20+.......+1/90
=1+1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+......+1/9-1/10
=1+1-1/10
=1+9/10
=1.9

1+ 1/2+1/6+1/+1/12+1/20+.......+1/90
=1+1/（1*2）+1/（2*3）+1/（3*4）+1/（4*5）……+1/9*10
=1+(1-1/2)+(1/2-1/3)+（1/3-1/4）+（1/4-1/5）……+(1/9-1/10)
=1+1-1/2+1/2-1/3+1/3-1/4+1/4-1/5……+1/9-1/10
=1+1-1/10
=19/10

1/2+1/6+1/12+1/20.+1/380 2%1+6%1+12%1+20%1+30%1 1/2+1/6+1/12+1/20+1/30 1/2-1/6-1/12-1/20-...-1/110 1/2,-1/6,1/12,-1/20,1/30 2/1+6/1+12/1+24/1+48/1 1/2+1/6+1/12+1/20+.1/90 2/1+6/1+12/1+20/1+...+2450/1 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72 1+1/2+1/12+1/6+1/20+1/30+1/40+1/56 (1-1/2)+(1-1/6)+(1-1/12)+...+(1-1/110)=? 1+1/2+1/6+1/12+1/20+1/30.+1/901+1/2+1/6+1/12+1/20+1/30+.+1/90简便计算 1/2+1/6+1/12+...+1/4054182 等于多少? 1/2+1/6+1/12+...+1/56=快 1/2+1/6+1/12+1/20= 1/2+1/6+1/12+.1/9900 1/2+1/6+1/12+.+1/9900