1乘以2乘以3分之1加2乘以3乘以4分之1,一直到9乘以10乘以11分之1的简便运算做么做_数学解答

1乘以2乘以3分之1加2乘以3乘以4分之1,一直到9乘以10乘以11分之1的简便运算做么做

人气：360 ℃　时间：2020-04-01 23:29:34

解答

1/2+1/3+1/4+1/5+1/6+1/7+1/8+1/9+1/10
=(1/2+1/3+1/6)+(1/4+1/5+1/10)+1/7+1/8+1/9
=1+11/20+1/8+1/7+1/9
=1+27/40+1/9+1/7
=1+283/360+1/7
=1+2341/2520
=4861/2520
9-（4861\2520)=不用说了吧
1*1\2+2*1\3+.+9*1\10=1-1\2+1-1\3+1-1\4+.1-1\10=9-(1\2+1\3+1\4+.1\10)