题目内容

1
5
÷(1-
1
3
×
1
2
)=
9
10
×[
7
8
÷(
4
5
+
1
4
)]=
1
4
-
1
4
×
1
2
)÷
1
4
=
5
6
+
9
8
×
5
9
×
8
9
=
5
6
+
5
6
÷
1
9
=
3
8
+
1
27
)×8+
19
27
=
X-
1
3
X=
2
3
1-
1
3
X=
2
3
 8X+
1
3
=
7
9
15
44
:X=
5
11
分析:(1)、(2)根据分数四则混合运算顺序计算;
(3)、(5)、(6)根据乘法分配律进行简算;
(4)根据乘法交换律进行简算;
(7)、(8)、(9)、(10)根据等式的性质进行解答.
解答:解:
(1)
1
5
÷(1-
1
3
×
1
2
),
=
1
5
÷(1-
1
6
),
=
1
5
÷
5
6

=
6
25


(2)
9
10
×[
7
8
÷(
4
5
+
1
4
)],
=
9
10
×[
7
8
÷
21
20
],
=
9
10
×
5
6

=
3
4


(3)(
1
4
-
1
4
×
1
2
)÷
1
4

=
1
4
×(1-
1
2
)÷
1
4

=
1
4
×
1
2
÷
1
4

=
1
4
÷
1
4
×
1
2

=1×
1
2

=
1
2


(4)
5
6
+
9
8
×
5
9
×
8
9

=
5
6
+
9
8
×
8
9
×
5
9

=
5
6
+
5
9

=
25
18


(5)9×
5
6
+
5
6
÷
1
9

=9×
5
6
+
5
6
×9,
=
5
6
×(9+9),
=
5
6
×18,
=15;

(6)(
3
8
+
1
27
)×8+
19
27

=
3
8
×8+
1
27
×8+
19
27

=3+
8
27
+
19
27

=3+(
8
27
+
19
27
),
=3+1,
=4;

(7)X-
1
3
X=
2
3

      
2
3
X=
2
3

   
2
3
2
3
=
2
3
÷
2
3

         X=1;

(8)1-
1
3
X=
2
3

 1-
1
3
X+
1
3
X=
2
3
+
1
3
X,
    
2
3
+
1
3
X=1,
 
2
3
+
1
3
X-
2
3
=1-
2
3

      
1
3
X=
1
3

   
1
3
1
3
=
1
3
÷
1
3

         X=1;

(9)8X+
1
3
=
7
9

  8X+
1
3
-
1
3
=
7
9
-
1
3

       8X=
4
9

    8X÷8=
4
9
÷8,
        X=
1
18


(10)
15
44
:X=
5
11

     
15
44
÷X=
5
11

  
15
44
÷X×X=
5
11
×X,
      
5
11
×X=
15
44

 
5
11
×X÷
5
11
=
15
44
÷
5
11

           X=
3
4
点评:考查了运算定律、简便运算,四则混合运算和解方程.注意运算顺序和运算法则,灵活运用所学的运算定律简便计算;解方程要根据等式的性质进行解答.
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