Question

小学6年级数学题求助

1/6+1/12+1/20+1/30+1/42+1/56+1/72

Answer 1

我们注意到 6=2*3,20=4*5,42=6*7....
所以
原式= (1/2-1/3)+(1/3-1/4)+(1/4-1/5)+.....(1/8-1/9
=1/2-1/9
=7/18

Answer 2

为1/2-1/9=7/18 wei 1/2-1/3+1/3-1/4.....=7/18

Answer 3

没问老师？

Answer 4

1/6+1/12+1/20+1/30+1/42+1/56+1/72
=1/2*1/3+1/3*1/4+1/4*1/5+1/5*1/6+1/6*1/7+1/7*1/8+1/72
=1/3*(1/2+1/4)+1/5*(1/4+1/6)+1/7*(1/6+1/8)+1/72
=1/3*3/4+1/5*5/12+1/7+7/24+1/72
=1/4+1/12+1/24+1/72
然后通分总会的吧。。。。我算出来7/18。