题目内容
简便运算
|
|
| 0.25+
|
考点:分数的简便计算
专题:运算顺序及法则
分析:(1)根据加法结合律进行简算;
(2)根据加法交换律和结合律进行简算;
(3)根据加法交换律和结合律进行简算;
(4)根据加法交换律和结合律进行简算.
(2)根据加法交换律和结合律进行简算;
(3)根据加法交换律和结合律进行简算;
(4)根据加法交换律和结合律进行简算.
解答:
解:(1)
+
+
=(
+
)+
=1+
=1
;
(2)
+
-
-
=(
-
)+(
-
)
=0+
=
;
(3)
+
+
-
=(
+
)+(
-
)
=1+0
=1;
(4)0.25+
+0.75+
=(0.25+0.75)+(
+
)
=1+1
=2.
5 |
7 |
2 |
7 |
3 |
4 |
=(
5 |
7 |
2 |
7 |
3 |
4 |
=1+
3 |
4 |
=1
3 |
4 |
(2)
3 |
8 |
2 |
9 |
3 |
8 |
1 |
9 |
=(
3 |
8 |
3 |
8 |
2 |
9 |
1 |
9 |
=0+
1 |
9 |
=
1 |
9 |
(3)
5 |
9 |
2 |
5 |
4 |
9 |
2 |
5 |
=(
5 |
9 |
4 |
9 |
2 |
5 |
2 |
5 |
=1+0
=1;
(4)0.25+
3 |
5 |
2 |
5 |
=(0.25+0.75)+(
3 |
5 |
2 |
5 |
=1+1
=2.
点评:考查了运算定律与简便运算,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定律简便计算.
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