ppcq.net
当前位置:首页 >> 1%5/6+7/12%9/20+11/30/42+15/56/72+19/90=?简便运... >>

1%5/6+7/12%9/20+11/30/42+15/56/72+19/90=?简便运...

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90=1/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90=3/4-9/20+11/30-13/42+15/56-17/72+19/90=6/20+11/30-13/42+15/56-17/72+19/90=20/30-13/42+15/56-17/72+19/90=15/42+15/56-17/72+19/90=35/56-17/72+19/90=28/72+19/90=35/90+19/90=54/90=27/45=3/5

1 - 5/6 + 7/12 - 9/20 + 11/30 - 13/42 + 15/56 - 17/72 + 19/90= 1 - (3+2)/6 + (4+3)/12 - (5+4)/20 + (6+5)/30 - (7+6)/42 + (8+7)/56 - (9+8)/72 + (10+9)/90= 1 - 1/2 - 1/3 + 1/3 + 1/4 - 1/4 - 1/5 + 1/5 + 1/6 - 1/6 - 1/7 + 1/7 + 1/8 - 1/8 - 1/9 + 1/9 + 1/10= 1/2 + 1/10= 5/10 + 1/10= 6/10= 3/5

这道题要用“分数拆分法”来做,就是说把题中的各个分数拆分成下面的算式,达到正负抵消,从而使计算简便.题中的“14/72”错啦,应该是“17/72”;还有“90/19”的分子分母写反啦,应该是“19/90”5/6=1/2+1/37/12=1/3+1/49/20=1/4

找规律,提示你,注意看分母.2*3=6,3*4=12,4*5=20,5*6=30,6*7=42,7*8=56,8*9=72,都是分母.

应该是1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90= 吧 1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90 =1-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)-(1/8+1/9)+(1/9+1/10) =1-1/2-1/3+1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+

=2/12+7/12+(22-27)/60+(45-52)/168+(76-85)/360=9/12-1/12-1/24-1/40=8/12-1/24-1/40=15/24-1/40=72/120=3/5

1-(1/2+1/3)+(1/3+1/4)-……

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90 =1-(1/2+1/3)+(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8) -(1/8+1/9)+(1/9+1/10) =1-1/2+1/10 =3/5 已计算,望采纳哦!谢谢! 说真得,这5分太辛苦了.

1-(2+3)/2*3+(3+4)/3*4-(4+5)/4*5+.-(10+11)/(11*10)=1-1/2-1/3+1/3+1/4-1/4-1/5+..-1/10-1/11=1-1/2-1/11=1/2-1/11=9/22

相关文档
mdsk.net | so1008.com | mwfd.net | jjdp.net | ncry.net | 网站首页 | 网站地图
All rights reserved Powered by www.ppcq.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com