计算下面各题(能简便的用简便方法) 8/9+7/12+3/4 5/12+7/8-9/20 2.85+2/7+2.15+4/7 3.4-(0.25+2/5)
7/8-7/27-20/272.15-(5/6-1/12)11/12+5/8+3/8+1/125-3/7-4/72/5*20+3/5*205/6-1/4+1/3...
7/8-7/27-20/27 2.15-(5/6-1/12) 11/12+5/8+3/8+1/12 5-3/7-4/7
2/5*20+3/5*20 5/6-1/4+1/3 展开
2/5*20+3/5*20 5/6-1/4+1/3 展开
2个回答
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8/9+7/12+3/4
=32/36+21/36+27/36
=80/36
=20/9
=2又2/9
5/12+7/8-9/20
=50/120+105/120-54/120
=101/120
2.85+2/7+2.15+4/7
=(2.85+2.15)+2/7+4/7
=5+6/7
=5又6/7
3.4-(0.25+2/5)
=3.4-0.4-0.25
=3-0.25
=2.75
7/8-7/27-20/27
=7/8-(7/27+20/27)
=7/8-1
=-1/8
2.15-(5/6-1/12)
=2.15-3/4
=2.15-0.75
=1.4
11/12+5/8+3/8+1/12
=(11/12+1/12)+(5/8+3/8)
=1+1
=2
5-3/7-4/7
=5-(3/7+4/7)
=5-1
=4
2/5*20+3/5*20
=(2+3)/5*20
=5/5*20
=20
5/6-1/4+1/3
=10/12-3/12+4/12
=11/12
=32/36+21/36+27/36
=80/36
=20/9
=2又2/9
5/12+7/8-9/20
=50/120+105/120-54/120
=101/120
2.85+2/7+2.15+4/7
=(2.85+2.15)+2/7+4/7
=5+6/7
=5又6/7
3.4-(0.25+2/5)
=3.4-0.4-0.25
=3-0.25
=2.75
7/8-7/27-20/27
=7/8-(7/27+20/27)
=7/8-1
=-1/8
2.15-(5/6-1/12)
=2.15-3/4
=2.15-0.75
=1.4
11/12+5/8+3/8+1/12
=(11/12+1/12)+(5/8+3/8)
=1+1
=2
5-3/7-4/7
=5-(3/7+4/7)
=5-1
=4
2/5*20+3/5*20
=(2+3)/5*20
=5/5*20
=20
5/6-1/4+1/3
=10/12-3/12+4/12
=11/12
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