题目内容

计算下面各题,注意使运算简便.
6
5
×
6
7
-
1
5
÷
7
6

12
7
-(
1
3
÷
7
15
+
4
5

84×(
5
12
-
2
7

2
3
×
5
7
+
2
3
×
2
7

3
4
×
1
9
+
1
4
÷9
5
3
-
2
7
-
5
7
分析:(1)(5)先将除法变为乘法,再根据乘法分配律简便计算;
(2)计算过程中,先算同分母分数;
(3)(4)根据乘法分配律简便计算;
(6)根据连减的简便方法计算.
解答:解:(1)
6
5
×
6
7
-
1
5
÷
7
6

=
6
5
×
6
7
-
1
5
×
6
7

=(
6
5
-
1
5
)×
6
7

=1×
6
7

=
6
7


(2)
12
7
-(
1
3
÷
7
15
+
4
5
),
=
12
7
-(
5
7
+
4
5
),
=
12
7
-
5
7
-
4
5

=1-
4
5

=
1
5


(3)84×(
5
12
-
2
7
),
=84×
5
12
-84×
2
7

=35-24,
=11;

(4)
2
3
×
5
7
+
2
3
×
2
7

=
2
3
×(
5
7
+
2
7

=
2
3
×1,
=
2
3


(5)
3
4
×
1
9
+
1
4
÷9,
=
3
4
×
1
9
+
1
4
×
1
9

=(
3
4
+
1
4
)×
1
9

=1×
1
9

=
1
9


(6)
5
3
-
2
7
-
5
7

=
5
3
-(
2
7
+
5
7
),
=
5
3
-1,
=
2
3
点评:此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.
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