澳洲留学酒店管理专业:1/2+1/6+1/12+1/20+1/30

来源:百度文库 编辑:查人人中国名人网 时间:2024/05/02 16:31:04
简算,求快,为什么

=3/6+1/6+1/12+1/20+1/30
=8/12+1/12+1/20+1/30
=15/20+1/20+1/30
=24/30+1/30
=5/6

1/2+1/6+1/12+1/20+1/30
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)
=1-1/6
=5/6

原式=1/2+1/6+1/12+1/20+1/30
=1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)+1/(5*6)
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)=1-1/6=5/6

1/2+1/6+1/12+1/20+1/30
=(6/12+2/12+1/12)+1/30
=9/12+1/30
=45/60+2/60
=47/60
=14/30
=7/15