题目内容
脱式计算.(能简算的用简便方法计算)
|
|
|
|
分析:①②③根据运算顺序直接计算,④利用加法交换律和结合律计算简便.
解答:解:①
-
+
,
=
-
+
,
=
;
②
-(
-
),
=
-
,
=
;
③
+(
-
),
=
+
,
=
;
④
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2.
5 |
6 |
3 |
4 |
2 |
3 |
=
10 |
12 |
9 |
12 |
8 |
12 |
=
3 |
4 |
②
3 |
4 |
5 |
6 |
1 |
3 |
=
3 |
4 |
1 |
2 |
=
1 |
4 |
③
2 |
3 |
3 |
5 |
1 |
2 |
=
2 |
3 |
1 |
10 |
=
23 |
30 |
④
4 |
9 |
3 |
10 |
5 |
9 |
7 |
10 |
=(
4 |
9 |
5 |
9 |
3 |
10 |
7 |
10 |
=1+1,
=2.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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