(1)39*149分之148+148*149分之86+48*149分之74(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2 (能简算的要简算)
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/23 12:16:52
![(1)39*149分之148+148*149分之86+48*149分之74(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2 (能简算的要简算)](/uploads/image/z/195132-12-2.jpg?t=%EF%BC%881%EF%BC%8939%2A149%E5%88%86%E4%B9%8B148%2B148%2A149%E5%88%86%E4%B9%8B86%2B48%2A149%E5%88%86%E4%B9%8B74%EF%BC%882%EF%BC%891%2A4%E5%88%86%E4%B9%8B2%2B4%2A7%E5%88%86%E4%B9%8B2%2B7%2A10%E5%88%86%E4%B9%8B2%2B10%2A13%E5%88%86%E4%B9%8B2%2B...97%2A100%E5%88%86%E4%B9%8B2+%EF%BC%88%E8%83%BD%E7%AE%80%E7%AE%97%E7%9A%84%E8%A6%81%E7%AE%80%E7%AE%97%EF%BC%89)
(1)39*149分之148+148*149分之86+48*149分之74(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2 (能简算的要简算)
(1)39*149分之148+148*149分之86+48*149分之74
(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2 (能简算的要简算)
(1)39*149分之148+148*149分之86+48*149分之74(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2 (能简算的要简算)
1
39*149分之148+148*149分之86+48*149分之74
=39*148/149+148*86/149+48*74/149
=(39*148+148*86+48*74)/149
=74(39*2+2*86+48)/149
=74[2(39+86)+48]/149
=74(250+48)/149
=74*298/149
=37
(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2
=2/(1*4)+2/(4*7)+2/(7*10)+2/(10*13)+.+2/(97*100)
=2/3[(1-1/4)+(1/4-1/7)+(1/7-1/10)+.+(1/97-1/100)]
=2/391-1/100)=2/3*99/100=33/50
(1)39*149分之148+148*149分之86+48*149分之74
=39*149分之148+86*149分之148+24*149分之148
=(39+86+24)*149分之148
= 149*149分之148
=148
(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2
=2/3×(1-1...
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(1)39*149分之148+148*149分之86+48*149分之74
=39*149分之148+86*149分之148+24*149分之148
=(39+86+24)*149分之148
= 149*149分之148
=148
(2)1*4分之2+4*7分之2+7*10分之2+10*13分之2+...97*100分之2
=2/3×(1-1/4+1/4-1/7+1/7-1/10+1/10-1/13+……+1/97-1/100)
=2/3×(1-1/100)
=2/3×99/100
=33/50
=0.66
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