题目内容
计算下面各题,注意使运算简便.
×
-
÷
-(
÷
+
)
84×(
-
)
×
+
×
×
+
÷9
-
-
.
| 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 |
| 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.
(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)
×
-
÷
,
=
×
-
×
=(
-
)×
,
=1×
,
=
;
(2)
-(
÷
+
),
=
-(
+
),
=
-
-
,
=1-
,
=
;
(3)84×(
-
),
=84×
-84×
,
=35-24,
=11;
(4)
×
+
×
=
×(
+
)
=
×1,
=
;
(5)
×
+
÷9,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(6)
-
-
,
=
-(
+
),
=
-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 |
| 2 |
| 7 |
=35-24,
=11;
(4)
| 2 |
| 3 |
| 5 |
| 7 |
| 2 |
| 3 |
| 2 |
| 7 |
=
| 2 |
| 3 |
| 5 |
| 7 |
| 2 |
| 7 |
=
| 2 |
| 3 |
=
| 2 |
| 3 |
(5)
| 3 |
| 4 |
| 1 |
| 9 |
| 1 |
| 4 |
=
| 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 |
=
| 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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