题目内容
计算下面各题,能简算的要简算.
9-
|
|
|
|
分析:(1)依据减法性质解答;
(2)运用加法交换律和结合律解答;
(3)按照先算括号里面的,再算括号外面的顺序解答;
(4)运用加法交换律解答.
(2)运用加法交换律和结合律解答;
(3)按照先算括号里面的,再算括号外面的顺序解答;
(4)运用加法交换律解答.
解答:解:(1)9-
-
,
=9-(
+
),
=9-1,
=8;
(2)
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2;
(3)
-(
+
),
=
-
,
=
;
(4)
-
+
,
=(
+
)-
,
=1-
,
=
.
1 |
5 |
4 |
5 |
=9-(
1 |
5 |
4 |
5 |
=9-1,
=8;
(2)
1 |
4 |
1 |
6 |
3 |
4 |
5 |
6 |
=(
1 |
4 |
3 |
4 |
1 |
6 |
5 |
6 |
=1+1,
=2;
(3)
3 |
5 |
2 |
15 |
1 |
3 |
=
3 |
5 |
7 |
15 |
=
2 |
15 |
(4)
5 |
7 |
1 |
3 |
2 |
7 |
=(
5 |
7 |
2 |
7 |
1 |
3 |
=1-
1 |
3 |
=
2 |
3 |
点评:本题考查知识点:(1)正确运用简便算法解决问题,(2)正确依据四则运算顺序进行计算.
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