求答案,速度 ,快
2个回答
2013-02-20 · 知道合伙人教育行家
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1、4/5*3/7+4/5*3/7
=4/5*(3/7+3/7)
=4/5*6/7
=24/35
2、4.375-3又2/7+3又5/8-1又5/7
=(4.375+3又5/8)-(3又2/7+1又5/7)
=8-5
=3
3、46.5*37+4.65*650-93
=46.5*37+4.65*10*65-93
=46.5*(37+65)-93
=46.5*100+46.5*2-93
=4650+93-93
=4650
4、7/8÷[(1/4+1/5)×7/8]
=7/8÷7/8÷9/20
=1÷9/20
=20/9
=2又2/9
5、28又7/10÷7
=28÷7+7/10÷7
=4+1/10
=4又1/10
6、
1/1*2+1/2*3+1/3*4+……+1/2010*2011
=1-1/2+1/2-1/3+1/3-1/4+....+1/2010-1/2011
=1-1/2011
=2010/2011
三、把x=5,y=4代入得:
原式=(3*5-2*4)/(4*5+2*4)=7/28=1/4
=4/5*(3/7+3/7)
=4/5*6/7
=24/35
2、4.375-3又2/7+3又5/8-1又5/7
=(4.375+3又5/8)-(3又2/7+1又5/7)
=8-5
=3
3、46.5*37+4.65*650-93
=46.5*37+4.65*10*65-93
=46.5*(37+65)-93
=46.5*100+46.5*2-93
=4650+93-93
=4650
4、7/8÷[(1/4+1/5)×7/8]
=7/8÷7/8÷9/20
=1÷9/20
=20/9
=2又2/9
5、28又7/10÷7
=28÷7+7/10÷7
=4+1/10
=4又1/10
6、
1/1*2+1/2*3+1/3*4+……+1/2010*2011
=1-1/2+1/2-1/3+1/3-1/4+....+1/2010-1/2011
=1-1/2011
=2010/2011
三、把x=5,y=4代入得:
原式=(3*5-2*4)/(4*5+2*4)=7/28=1/4
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