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第一题有空格的是带分数1)[﹙10.75-411/12﹚×27/11]÷[﹙1.125+1/12﹚÷﹙2.25÷1010/11﹚]2)1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙100×103﹚3)1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/904)﹙1/11+1/
题目详情
第一题有空格的是带分数
1) [﹙10.75-4 11/12﹚×2 7/11]÷[﹙1.125+1/12﹚÷﹙2.25÷10 10/11﹚]
2) 1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙100×103﹚
3) 1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
4) ﹙1/11+1/21+1/31﹚×﹙1/21+1/31+1/41﹚-﹙1/11+1/21+1/31+1/41﹚×﹙1/21+1/31﹚
5) 1/﹙1×4﹚+1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙22×25﹚
1) [﹙10.75-4 11/12﹚×2 7/11]÷[﹙1.125+1/12﹚÷﹙2.25÷10 10/11﹚]
2) 1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙100×103﹚
3) 1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
4) ﹙1/11+1/21+1/31﹚×﹙1/21+1/31+1/41﹚-﹙1/11+1/21+1/31+1/41﹚×﹙1/21+1/31﹚
5) 1/﹙1×4﹚+1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙22×25﹚
▼优质解答
答案和解析
1) [﹙10.75-4 11/12﹚×2 7/11]÷[﹙1.125+1/12﹚÷﹙2.25÷10 10/11﹚]
= [﹙129/12-59/12﹚×29/11]÷[﹙27/24+2/24﹚÷﹙9/4÷120/11﹚]
= [﹙70/12﹚×29/11]÷[﹙29/24﹚÷﹙33/160﹚]
= [﹙70×29)/(12×11)]÷[﹙29×160)/(24×33﹚]
= [﹙70×29)/(12×11)]x[(24×33﹚/(29×160)]
= [﹙70×29)(24×33﹚] / [(12×11)(29×160)]
= ﹙7×3﹚ / 8
=21/8
=2又5/6
2)
1/﹙4×7﹚=1/3(1/4-1/7),
1/﹙7×10﹚=1/3(1/7-1/10),
.
1/﹙100×103﹚=1/3(1/100-1/103),
∴1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙100×103﹚
=1/3(1/4-1/7+……+1/100-1/103)
=1/3*(1/4-1/103)
=1/3(99/412)
=33/412
3) 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
=15/20-9/20+11/30-13/42+15/56-17/72+19/90
=3/10+11/30-13/42+15/56-17/72+19/90
=2/3-13/42+15/56-17/72+19/90
=14/42-13/42+15/56-17/72+19/90
=4/168+45/168-17/72+19/90
=7/24-17/72+19/90
=21/72-17/72+19/90
=4/72+19/90
=5/90+19/90
=24/90
=4/15
4) (1/11+1/21+1/31)×﹙1/21+1/31+1/41﹚-﹙1/11+1/21+1/31+1/41﹚×﹙1/21+1/31﹚
= (1/11+1/21+1/31)×[(1/21+1/31)+1/41]-[(1/11+1/21+1/31)+1/41]×(1/21+1/31)
= [(1/11+1/21+1/31)×(1/21+1/31)+(1/11+1/21+1/31)×1/41]-
-[(1/11+1/21+1/31)×(1/21+1/31)+1/41×(1/21+1/31)]
= 【(1/11+1/21+1/31)×(1/21+1/31)】+{(1/11+1/21+1/31)×1/41}-
-【(1/11+1/21+1/31)×(1/21+1/31)】-{1/41×(1/21+1/31)}
={(1/11+1/21+1/31)×1/41}-{1/41×(1/21+1/31)}
={1/11x1/41+(1/21+1/31)×1/41}-{1/41×(1/21+1/31)}
=1/11x1/41
=1/451
5) 1/﹙1×4﹚+1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙22×25﹚
=1/3(1-1/4+1/4-1/7+……+1/22-1/25)
=1/3(1-1/25)
=1/3x24/25
=8/25
= [﹙129/12-59/12﹚×29/11]÷[﹙27/24+2/24﹚÷﹙9/4÷120/11﹚]
= [﹙70/12﹚×29/11]÷[﹙29/24﹚÷﹙33/160﹚]
= [﹙70×29)/(12×11)]÷[﹙29×160)/(24×33﹚]
= [﹙70×29)/(12×11)]x[(24×33﹚/(29×160)]
= [﹙70×29)(24×33﹚] / [(12×11)(29×160)]
= ﹙7×3﹚ / 8
=21/8
=2又5/6
2)
1/﹙4×7﹚=1/3(1/4-1/7),
1/﹙7×10﹚=1/3(1/7-1/10),
.
1/﹙100×103﹚=1/3(1/100-1/103),
∴1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙100×103﹚
=1/3(1/4-1/7+……+1/100-1/103)
=1/3*(1/4-1/103)
=1/3(99/412)
=33/412
3) 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
=15/20-9/20+11/30-13/42+15/56-17/72+19/90
=3/10+11/30-13/42+15/56-17/72+19/90
=2/3-13/42+15/56-17/72+19/90
=14/42-13/42+15/56-17/72+19/90
=4/168+45/168-17/72+19/90
=7/24-17/72+19/90
=21/72-17/72+19/90
=4/72+19/90
=5/90+19/90
=24/90
=4/15
4) (1/11+1/21+1/31)×﹙1/21+1/31+1/41﹚-﹙1/11+1/21+1/31+1/41﹚×﹙1/21+1/31﹚
= (1/11+1/21+1/31)×[(1/21+1/31)+1/41]-[(1/11+1/21+1/31)+1/41]×(1/21+1/31)
= [(1/11+1/21+1/31)×(1/21+1/31)+(1/11+1/21+1/31)×1/41]-
-[(1/11+1/21+1/31)×(1/21+1/31)+1/41×(1/21+1/31)]
= 【(1/11+1/21+1/31)×(1/21+1/31)】+{(1/11+1/21+1/31)×1/41}-
-【(1/11+1/21+1/31)×(1/21+1/31)】-{1/41×(1/21+1/31)}
={(1/11+1/21+1/31)×1/41}-{1/41×(1/21+1/31)}
={1/11x1/41+(1/21+1/31)×1/41}-{1/41×(1/21+1/31)}
=1/11x1/41
=1/451
5) 1/﹙1×4﹚+1/﹙4×7﹚+1/﹙7×10﹚+……+1/﹙22×25﹚
=1/3(1-1/4+1/4-1/7+……+1/22-1/25)
=1/3(1-1/25)
=1/3x24/25
=8/25
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