题目内容
计算,能简算的要简算.
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分析:(1)运用减法的性质简算;
(2)先算括号内的,再算括号外的;
(3)运用加法交换律与结合律简算;
(4)运用加法交换律简算;
(5)(6)通分计算.
(2)先算括号内的,再算括号外的;
(3)运用加法交换律与结合律简算;
(4)运用加法交换律简算;
(5)(6)通分计算.
解答:解:(1)
-(
+
),
=
-
-
,
=1-
,
=
;
(2)
+(
-
),
=
+
,
=
;
(3)
-
+
-
,
=(
+
)-(
+
),
=1-1,
=0;
(4)
+(
+
),
=
+
+
,
=(
+
)+
,
=1+
,
=
;
(5)
-
-
,
=
-
-
,
=
;
(6)
-
+
,
=
-
+
,
=
.
| 15 |
| 7 |
| 8 |
| 7 |
| 9 |
| 14 |
=
| 15 |
| 7 |
| 8 |
| 7 |
| 9 |
| 14 |
=1-
| 9 |
| 14 |
=
| 5 |
| 14 |
(2)
| 6 |
| 7 |
| 4 |
| 5 |
| 3 |
| 10 |
=
| 6 |
| 7 |
| 1 |
| 2 |
=
| 19 |
| 14 |
(3)
| 7 |
| 10 |
| 1 |
| 4 |
| 3 |
| 10 |
| 3 |
| 4 |
=(
| 7 |
| 10 |
| 3 |
| 10 |
| 1 |
| 4 |
| 3 |
| 4 |
=1-1,
=0;
(4)
| 5 |
| 12 |
| 6 |
| 7 |
| 7 |
| 12 |
=
| 5 |
| 12 |
| 6 |
| 7 |
| 7 |
| 12 |
=(
| 5 |
| 12 |
| 7 |
| 12 |
| 6 |
| 7 |
=1+
| 6 |
| 7 |
=
| 6 |
| 7 |
(5)
| 7 |
| 8 |
| 1 |
| 6 |
| 5 |
| 12 |
=
| 21 |
| 24 |
| 4 |
| 24 |
| 10 |
| 24 |
=
| 7 |
| 24 |
(6)
| 13 |
| 12 |
| 5 |
| 6 |
| 11 |
| 24 |
=
| 26 |
| 24 |
| 20 |
| 24 |
| 11 |
| 24 |
=
| 17 |
| 24 |
点评:考查了分数的四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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