题目内容

正确、合理、灵活地计算.
66×
4
65
         
11
12
+
5
8
-(
3
8
-
1
12
)        
1
6
+
1
9
-
1
12
)×4÷
1
9

(2-
3
4
×
4
5
)÷(
1
12
+
4
15
)         
6
11
×
3
8
+
7
11
÷
8
3
-
2
11
×0.375.
考点:分数的四则混合运算,分数的简便计算
专题:运算顺序及法则
分析:(1)(3)(5)利用乘法分配律简算;
(2)利用减法的性质和加法结合律简算;
(4)先算乘法和加法,再算减法,最后算除法.
解答: 解:(1)66×
4
65
  
=65×
4
65
+1×
4
65

=4+
4
65

=4
4
65

      
(2)
11
12
+
5
8
-(
3
8
-
1
12

=
11
12
+
1
12
+(
5
8
-
3
8

=1+
1
4

=1
1
4


(3)(
1
6
+
1
9
-
1
12
)×4÷
1
9

=(
1
6
+
1
9
-
1
12
)×4×9
=
1
6
×4×9+
1
9
×4×9-
1
12
×4×9
=6+4-3
=7;

(4)(2-
3
4
×
4
5
)÷(
1
12
+
4
15

=(2-
3
5
)÷
7
20

=
7
5
×
20
7

=4;

(5)
6
11
×
3
8
+
7
11
÷
8
3
-
2
11
×0.375
=
6
11
×
3
8
+
7
11
×
3
8
-
2
11
×0.375
=(
6
11
+
7
11
-
2
11
)×
3
8

=1×
3
8

=
3
8
点评:分数混合运算的关键是抓住运算顺序,正确按运算顺序计算,适当利用运算定律简算.
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