题目内容
能简算的要简算.
18
-(8
-1
)
1
-
+
+
-
+
-〔
-(
+
)〕
18
5 |
7 |
5 |
7 |
3 |
4 |
1
2 |
3 |
2 |
7 |
5 |
7 |
8 |
7 |
5 |
8 |
1 |
7 |
1 |
8 |
5 |
9 |
2 |
3 |
2 |
5 |
1 |
10 |
考点:分数的四则混合运算,分数的简便计算
专题:运算顺序及法则,运算定律及简算
分析:(1)运用减法性质解答,
(2)运用加法结合律解答,
(3)运用加法交换律和结合律解答,
(4)按照先算小括号里面的,再算中括号里面的,最后算括号外面的顺序计算解答.
(2)运用加法结合律解答,
(3)运用加法交换律和结合律解答,
(4)按照先算小括号里面的,再算中括号里面的,最后算括号外面的顺序计算解答.
解答:
解:(1)18
-(8
-1
)
=18
-8
+1
=10+1
=11
;
(2)1
-
+
=1
+(
-
)
=1
+
=2
;
(3)
+
-
+
=(
-
)+(
+
)
=1+
=1
;
(4)
-[
-(
+
)]
=
-[
-
]
=
-
=
.
5 |
7 |
5 |
7 |
3 |
4 |
=18
5 |
7 |
5 |
7 |
3 |
4 |
=10+1
3 |
4 |
=11
3 |
4 |
(2)1
2 |
3 |
2 |
7 |
5 |
7 |
=1
2 |
3 |
5 |
7 |
2 |
7 |
=1
2 |
3 |
3 |
7 |
=2
2 |
21 |
(3)
8 |
7 |
5 |
8 |
1 |
7 |
1 |
8 |
=(
8 |
7 |
1 |
7 |
5 |
8 |
1 |
8 |
=1+
3 |
4 |
=1
3 |
4 |
(4)
5 |
9 |
2 |
3 |
2 |
5 |
1 |
10 |
=
5 |
9 |
2 |
3 |
1 |
2 |
=
5 |
9 |
1 |
6 |
=
7 |
18 |
点评:本题考查知识点:(1)依据四则运算计算方法正确进行计算,(2)正确运用简便方法解决问题.
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