如题所述
1题:原式=1/3-1/4+1/4-1/5+1/5-···+1/98-1/99
=1/3-1/99
=32/99
2题:原式=1.2*30*1.09+1.2×67.3
=1.2×(67.3+32.7)
=1.2*100
=120
3题:原式=1.8*40*2.09-1.8*73.6
=1.8*(83.6-73.6)
=1.8*10
=18
4题:原式=4*1.7*8*2.1*19.3*8*4*0.1
=4*8*(1.7*2.1+19.3*0.1)
=32*5
=160
5题:原式=1.2*40*1.08+1.2×56.8
=1.2*(43.2+56.8)
=1.2*100
=120
6题:原式=0.9999×0.7+0.1111*9*0.3
=0.9999*0.7+0.9999*0.3
=0.9999*(0.7+0.3)
=0.9999
解释:1题.经过尝试可发现:1/(3*4)=1/3-1/4,之后所有的都以此类推就ok了。
2到6:思路都一样,找到一个最小公约数,之后把这个数提出来,括号里面多半是10、100这样的数,ok了。
7.2000*1999-1999*1998+1998*1997-1997*1996
=1999*(2000-1998)+1997*(1998-1996)
=1999*2+1997*2
=(1999+1997)*2
=(2000-1+2000-3)*2
=8000-8
=7992
8.(0.75*42.7+57.3-0.573*25)/3*7972
=(0.75*42.7+57.3*1-57.3*0.25)/3*7972
=[0.75*42.7+57.3(1-0.25)]/3*7972
=[0.75*42.7+57.3*0.75]/3*7972
=[(42.7+57.3)*0.75]/3*7972
=75/3*7972
=25*7972
=199300
9./(1*2) + 1/(2*3) + 1/(3*4) + 1/(4*5) + 1/(5*6) + …… + 1/(99*100)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+......+1/98-1/99+1/99-1/100
=1-1/100
=99/100
抱歉实在太难找了,这里只有9道。
=1/3-1/99
=32/99
2题:原式=1.2*30*1.09+1.2×67.3
=1.2×(67.3+32.7)
=1.2*100
=120
3题:原式=1.8*40*2.09-1.8*73.6
=1.8*(83.6-73.6)
=1.8*10
=18
4题:原式=4*1.7*8*2.1*19.3*8*4*0.1
=4*8*(1.7*2.1+19.3*0.1)
=32*5
=160
5题:原式=1.2*40*1.08+1.2×56.8
=1.2*(43.2+56.8)
=1.2*100
=120
6题:原式=0.9999×0.7+0.1111*9*0.3
=0.9999*0.7+0.9999*0.3
=0.9999*(0.7+0.3)
=0.9999
解释:1题.经过尝试可发现:1/(3*4)=1/3-1/4,之后所有的都以此类推就ok了。
2到6:思路都一样,找到一个最小公约数,之后把这个数提出来,括号里面多半是10、100这样的数,ok了。
7.2000*1999-1999*1998+1998*1997-1997*1996
=1999*(2000-1998)+1997*(1998-1996)
=1999*2+1997*2
=(1999+1997)*2
=(2000-1+2000-3)*2
=8000-8
=7992
8.(0.75*42.7+57.3-0.573*25)/3*7972
=(0.75*42.7+57.3*1-57.3*0.25)/3*7972
=[0.75*42.7+57.3(1-0.25)]/3*7972
=[0.75*42.7+57.3*0.75]/3*7972
=[(42.7+57.3)*0.75]/3*7972
=75/3*7972
=25*7972
=199300
9./(1*2) + 1/(2*3) + 1/(3*4) + 1/(4*5) + 1/(5*6) + …… + 1/(99*100)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+......+1/98-1/99+1/99-1/100
=1-1/100
=99/100
抱歉实在太难找了,这里只有9道。
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第1个回答 2012-08-26
24555553434583838438855245245244444444444444452343242342342342342342343423432432423422243234323333423423423423432473484648844838
第2个回答 2012-08-26
去百度文库找找