1.1/2+1/6+1/12+1/20+1/30+1/42+1/50+1/72+1/90=?

来源：学生作业帮编辑：神马作文网作业帮分类：数学作业时间：2024/11/06 14:42:38

1.1/2+1/6+1/12+1/20+1/30+1/42+1/50+1/72+1/90=?
2.1有1/3-7/12+9/20-11/30+13/42-15/56=?

1/2+1/6+1/12+1/20+1/30+1/42+1/50+1/72+1/90=1/1*2+1/2*3+1/3*4+...+1/9*10
=1-1/2+1/2-1/3+...+1/9-1/10
=1-1/10
=9/10
1又1/3-7/12+9/20-11/30+13/42-15/56
=1+1/3-(1/3+1/4)+(1/4+1/5)+...-(1/7+1/8)
=1+1/3-1/3-1/4+1/4+1/5+...-1/7-1/8
=1-1/8
=7/8

1.1/2+1/6+1/12+1/20+1/30+1/42+1/50+1/72+1/90=? 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90= 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=多少 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=______ 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+.1/9900 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110 谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90 若a=1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132+1/ 2/1+6/1+12/1+20/1+30/1+42/1+56/1+72/1+90/1等于多少 2\1-6\1-12\1-20\1-30\1-42\1-56\1-72\1-90\1 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90