(1/2-1/4+1/6-1/8+1/10-1/12+……+1/198-1/200)÷(1/51+1/52+1/53+1/54+……1/100)

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/15 08:30:16

(1/2-1/4+1/6-1/8+1/10-1/12+……+1/198-1/200)÷(1/51+1/52+1/53+1/54+……1/100)
(1/2-1/4+1/6-1/8+1/10-1/12+……+1/198-1/200)÷(1/51+1/52+1/53+1/54+……1/100)

(1/2-1/4+1/6-1/8+1/10-1/12+……+1/198-1/200)÷(1/51+1/52+1/53+1/54+……1/100)
1/2-1/4+1/6-1/8+1/10-1/12+…+1/198-1/200
=(1-1/2+1/3-1/4+ ...+1/99-1/100)/2
=[(1+1/2+ ...+1/99+1/100)-2(1/2+1/4+ ...+1/98+1/100)]/2
=[(1+1/2+ ...+1/99+1/100)-(1+1/2+ ...+1/49+1/50)]/2
=(1/51+1/52+1/53+ ...+1/99+1/100)/2
所以原式
=(1/2)(1/51+1/52+1/53+ ...+1/99+1/100)/(1/51+1/52+1/53+…+1/100)
=1/2