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7/12-9/20+11/30-13/42+15/56-17/72=?
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第1个回答 2013-12-20
7/12-9/20+11/30-13/42+15/56-17/72
=1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8-1/8-1/9=1/3-1/9=2/9
相似回答
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
简便方法计算?
答：
计算 7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72 =
(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)-(1/8+1/9)=1/3-1/9 =3/9-1/9 =2/9
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
答：
答案如图
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
+19/90巧算答案
答：
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/72+19/90 =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 =1/3+1/10 =13/30
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
+19/90
=?
答：
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/72+19/90 =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 =1/3+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 =1/3+1/10 =10/30+3/30 =13/30 ...
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
+19/90怎么做
答：
=(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)=1/3-1/10 =7/
30
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
+19/90
=?
答：
7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/72+19/90 =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 =1/3+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 =1/3+1/10 =10/30+3/30 =13/30 ...
1+1/2-5/6+7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
不通分,如何简便计算...
答：
1+1/2-5/6+7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72 =
1+1/2-(1/2+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+1/2-1/2-1/3+1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7+1/7+1/8-1/8-1/9 =1-1/9 =8/9 ...
1-5
\6+7\
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72
答：
原式=1/6 + 7/
12 - 9
/
20 + 11
/
30 - 13
/
42 + 15
/
56 - 17
/
72 =
3/4 - 9/20 + 11/30 - 13/40 + 15/
56 - 17
/72 =3/10 + 11/30 - 13/42 + 15/56 - 17/72 =2/3 - 13/42 + 15/56 - 17/72 =5/14 + 15/56 - 17/72 =5/8 - 17/72 =7/18 ...
3/2-5/6+7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72=
答：
3/2-5/6+7/
12-9
/
20+11
/
30-13
/
42+15
/
56-17
/
72 =
(1+1/2)-(1/2+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)=1-1/9 =8/9
大家正在搜
2019.12.20
2 6 12 20规律
56比29与47的和少多少
2跟20怎么算出来的47
12.20
12.25
12.23
2,6,(),12
12月20日
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