不要应用题!要计算
1*2*3+2*3*4+3*4*5+···+25*26*27+26*27*28
= (2³ - 2) + (3³ - 3) + â¦â¦ + (27³ - 27)
= 1³ + 2³ + 3³ + â¦â¦ + 27³ - (1+2+3+â¦â¦+27)
å¥ç¨è¿ç»ç«æ¹åå ¬å¼ãçå·®æ°åæ±åå ¬å¼
= ï¼1+2+3+â¦â¦+27)^2 - (1+27) * 27 / 2
= [(1+27)*27/2]^2-378
=378^2-378
=378*377
=142506
1x2+2x3+3x4+4x5+...+2002x2003
=1/3*1*2*3+1/3[2*3*4-1*2*3]+1/3[3*4*5-2*3*4]+....+1/3[2002*2003*2004-2001*2002*2003]
=1/3*2002*2003*2004
=2678684008
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设AB两å°ç¸è·xåç±³
[2/(3+2)x]/[3Ã(1+1/5)]=[3/(3+2)x-26]/[2Ã(1+2/5)]
x/9=3x/14-130/14
13x/126=130/14
x=90
1/1*3+1/2*4+1/3*5+1/4*6+1/5*7......1/98*100+1/99*101
=ï¼1-1/3+1/2-1/4+1/3-1/5+1/4-1/6+1/5-1/7+â¦â¦+1/98-1/100+1/99-1/101ï¼Ã·2
=ï¼1+1/2-1/100-1/101ï¼Ã·2
=15049/10100÷2
=15049/20200
ç²ãä¹ãä¸ä¸äººåå»ååºè´ç©ï¼ç²è±é±æ°ç1/2çäºä¹è±é±æ°ç1/3ï¼ä¹è±é±æ°ç3/4çäºä¸è±é±æ°ç3/5ï¼ç»æä¸æ¯ç²å¤è±äº98å é±ï¼é®ä»ä»¬å ±è±äºå¤å°é±?
98÷ï¼3/4÷3/5-1/3÷1/2ï¼Ãï¼1+1/3÷1/2+3/4÷3/5ï¼
=98÷ï¼5/4-2/3ï¼Ãï¼1+2/3+5/4ï¼
=98÷7/12Ã35/12
=168Ã35/12
=490å
ç²åä¹è¿è¡100ç±³è·æ¥æ¯èµï¼å设两人çé度ä¿æä¸åï¼ï¼å½ç²è·äº75ç±³æ¶ï¼ä¹è·äº60ç±³ãé£ä¹ï¼å½ç²å°è¾¾ç»ç¹æ¶ï¼ä¹è·äºå¤å°ç±³ ï¼
100Ã60/75
=100Ã4/5
=80ç±³
6åä¹1+12åä¹1+24åä¹1+48åä¹1+96åä¹1+192åä¹1
=1/6Ãï¼1+1/2+1/4+1/8+1/16+1/32ï¼
=1/6Ãï¼1-1/32ï¼
=1/6-1/192
=31/192
å æ°5ç个æ°å³å®æ«å°¾0ç个æ°
2008÷5=401个ï¼åæ´ï¼
2008÷25=80个ï¼åæ´ï¼
2008÷125=16个ï¼åæ´ï¼
2008÷625=3ï¼åæ´ï¼
401+80+16+3=500个
1*2*3*4*5*6*â¦â¦*2008æ«å°¾æ500个0
ä¸è¾æ±½è½¦ä»ç²å°å¼å¾ä¹å°ï¼å¦æ车éæé«20%ï¼å¯ä»¥æ¯åå®æ¶é´æå1å°æ¶å°è¾¾ï¼å¦æ以åé度è¡é©¶120åç±³åï¼åå°é度æé«25%ï¼åå¯æå40åéå°è¾¾ï¼æ±ç²ãä¹ä¸¤å°ç¸è·å¤å°åç±³ï¼
40å=2/3å°æ¶
åå®æ¶é´1÷ã1-1/ï¼1+20%ï¼ã=6å°æ¶
åæ¥é度ã120-120/ï¼1+25%ï¼ã÷ã6-2/3-6/ï¼1+25%ï¼ã=24÷8/15=45åç±³/å°æ¶
ç²ä¹ç¸è·45Ã6=270åç±³
å(1)çæ°å¦ææ«æµè¯å ¨çå¹³åæ绩92å,ç·çåå æµè¯ç人æ°æ¯18人,å¹³ååæ¯89å,女ççå¹³ååæ¯94å,æ±å¥³ç人æ°(ç¨å°å¦å年级çæ¹æ³å)
ï¼92-89ï¼Ã18÷ï¼94-92ï¼=27人
éæéªè½¦æ è¡,平路æ¯å¤©èµ°38åç±³,山路æ¯å¤©èµ°23åç±³ï¼ä»15å¤©å ±èµ°äº450åç±³ãé®è¿æé´ä»èµ°äºå¤å°å米山路
ï¼38*15-450ï¼/ï¼38-23ï¼*23=8*23=184å米追é®
æ¯ç®åç计ç®ï¼ä¸æ¯åºç¨é¢
追çåé¢çå°±æ¯å
追é®æè¦20é¢è®¡ç®
追ç10/21*2/5-2/5*3/7
=ï¼10/21-3/7ï¼*2/5
=1/21*2/5
=2/105
(2Ã2+4Ã4+........+100Ã100)-(1Ã1+3Ã3.......+99Ã99)/1+2+.....+10+9+....+1
=[(2+1)x(2-1)+(4+3)x(4-3)+........+(100+99)Ã(100-99)]/(10x10)
=(1+2+3+4+â¦â¦+99+100ï¼/100
=(1+100)x100/2/100
=101/2
=50.5
8/9ä¹ã3/7é¤ä»¥ï¼3/2ï¼7/1ï¼ã
=8/9ä¹ã3/7é¤ä»¥21/17ã
=8/9ä¹17/49
=136/441
0.999ä¹1.3å0.111ä¹2.7
=0.999Ã1.3-0.999Ã0.3
=0.999Ãï¼1.3-0.3ï¼
=0.999
1+3å1/6+5å1/12+7å1/20+9å1/30+11å1/42+13å1/56+15å1/72+17å1/90+19å1/110
=ï¼1+3+5+7+9+11+13+15+17+19ï¼+ï¼1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110ï¼
=ï¼1+19ï¼Ã10/2+ï¼1/2-1/3+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+1/10-1/11ï¼
=100+ï¼1/2-1/11ï¼
=100+9/22
=100å9/12
2/1X3+2/3X5+2/5X7+......+2/2001X2003+2/2003+2005
=1-1/3+1/3-1/5+1/5-1/7+â¦â¦+1/2001-1/2003+1/2003-1/2005
=1-1/2005
=2004/2005
35/6-49/12+63/20-77/30+91/42-105/56
=ï¼6-4+3+2-2ï¼-1/6-1/12+3/20+1/6+1/8
=5-1/12+3/20+1/8
=5å23/120
1/2+1/3+3/4+2/5+5/7+7/8+9/20+10/21+11/24+12/35
=1/2+1/3+3/4+2/5+5/7+7/8+1/4+1/5+1/3+1/7+1/3+1/8+1/5+1/7
=1/2+(1/3+1/3+1/3)+(3/4+1/4)+(2/5+1/5+1/5)+(5/7+1/7+1/7)+(7/8+1/8)
=1/2+1+1+1+1+1
=6.5
1/1X5+1/5X9+1/9X13+......+1/97X101
=(1-1/5+1/5-1/9+1/9-1/13+â¦â¦+1/97-1/101ï¼Ã·4
=ï¼1-1/101ï¼Ã·4
=100/101÷4
=25/101
19åä¹2*0.25*68
=19åä¹2*ï¼0.25*68ï¼
=19åä¹2*17
=19åä¹34
44x58+45x57
=44x57+44+45x57
=(44+45)x57+44
=99x57+44
=100x57-57+44
=5700-13
=5687
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å¯ä»¥åç»æä¸äºåï¼è¦çæ¡ï¼å åå¦
追ç[15.5-ï¼1.75Ã5/7+1å3/4Ã2/7ï¼]÷1å3/8
=[15.5-ï¼1.25+0.5ï¼]÷1å3/8
=[15.5-1.75]÷11/8
=13.75Ã8/11
=10
1999÷ï¼1999+1999/2000ï¼+1/2001
=1999÷1999÷ï¼1999÷1999+1999/2000÷1999ï¼+1/2001
=1÷ï¼1+1/2000ï¼+1/2001
=2000/2001+1/2001
=1
7åä¹4ä¹23å13åä¹12å 7åä¹4ä¹13åä¹1+16ä¹7份ä¹1
=7åä¹4ä¹23å13åä¹12å 7åä¹4ä¹13åä¹1+4ä¹7份ä¹4
=7åä¹4ä¹ï¼23å13åä¹12+13åä¹1+4ï¼
=7åä¹4ä¹28
=16
8å 3/5ï¹£1.5÷[1 å2/3Ãï¼3å 1/6ï¹¢1 å1/3ï¼ï¼½
=8å 3/5ï¹£1.5÷[5/3Ã4.5ï¼½
=8å 3/5ï¹£1.5÷7.5
=8.6-0.2
=8.4
[2011/3]+[2011/9]+[2011/27]+[2011/81]+[2011/243]+[2011/729]+[2011/2187]
=2011Ãï¼1/3+1/9+1/27+1/81+1/243+1/729+1/2187ï¼
=2011Ãï¼1-1/2187ï¼Ã·ï¼3-1ï¼
=2011Ã2186/2187÷2
=2011Ã1093/2187
=2198023/2178
â1009.2
1.2+1.5+1.8+2.1+...+4.5+4.8
=ï¼1.2+4.8ï¼Ã13÷2
=3Ã13
=39
(1-1/2002)+(1-1/2002*2)+(1-1/2002*3)+.......+(1-1/2002*2001)+(1-1/2002*2002)
=2002-1/2002Ã(1+2+3+â¦â¦+2001+2002ï¼
=2002-1/2002Ãï¼1+2002)Ã2002/2
=2002-2003/2
=2002-1001.5
=1000.5
19961997*19971996-19961996*19971997
=19971996+19961996*19971996-19961996*19971997
=19971996+19961996*ï¼19971996-19971997ï¼
=19971996-19961996
=10000
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