1+3x1/6+5x1/12+7x1/20+9x1/30+11x1/42=？

更新时间2021-06-13 10:44:18

看你题目中的  x  应该是个乘号 ✖，这就是一个分数运算题， 按这个理解解答如下

1+3x1/6+5x1/12+7x1/20+9x1/30+11x1/42

=1+1/2+5/12+7/20+3/10+11/42  

=1+(1/2+7/20+3/10)+(5/12+11/42)   应用交换律结合律，把好加的结合先加起来

=1+（10+7+6）/20+(35+22)/84          两个（   ）里分别通分相加

=1+23/20+57/84

=2+3/20+19/28

=2+(21+95)/(4*5*7)

=2+116/140

=2又29/35

1+3×(1/6)+5×(1/12)+7×(1/20)+9×(1/30)+11×(1/42)

=1+1/2+5/12+7/20+3/10+11/42

=1+1/2+(2+3)/12+(2+5)/20+(5-2)/10+(14-3)/42

=1+1/2+1/6+1/4+1/10+1/4+1/2-1/5+1/3-1/14

=1+(1/2+1/2)+(1/6+1/3)+(1/4+1/4)-(1/5-1/10)-1/14

=3-(1/10+1/14)

=3-6/35

=(2+29/35)