题目内容
用你喜欢的方法计算下面各题.
+
+
-(
-
)
+
+
+
+
+
2-
-
+
+
+
.
1 |
5 |
5 |
6 |
2 |
3 |
7 |
18 |
5 |
18 |
1 |
9 |
5 |
24 |
1 |
4 |
2 |
3 |
3 |
4 |
4 |
9 |
1 |
4 |
2 |
9 |
2 |
7 |
3 |
7 |
3 |
8 |
2 |
7 |
1 |
8 |
5 |
7 |
分析:(1)运用加法结合律简算;
(2)先去掉括号,括号外是减法,去括号时把括号内的加法变成减法,减法变成加法;
(3)按照从左到右的顺序计算;
(4)运用加法结合律简算;
(5)根据连续减去两个数,等于减去这两个数的和简算;
(6)运用加法结合律简算.
(2)先去掉括号,括号外是减法,去括号时把括号内的加法变成减法,减法变成加法;
(3)按照从左到右的顺序计算;
(4)运用加法结合律简算;
(5)根据连续减去两个数,等于减去这两个数的和简算;
(6)运用加法结合律简算.
解答:解:(1)
+
+
,
=
+(
+
),
=
+
,
=
;
(2)
-(
-
),
=
-
+
,
=
+
,
=
;
(3)
+
+
,
=
+
,
=
;
(4)
+
+
+
,
=(
+
)+(
+
),
=1+
,
=1
;
(5)2-
-
,
=2-(
+
),
=2-
,
=1
;
(6)
+
+
+
,
=(
+
)+(
+
),
=
+1,
=1
.
1 |
5 |
5 |
6 |
2 |
3 |
=
1 |
5 |
5 |
6 |
2 |
3 |
=
1 |
5 |
3 |
2 |
=
17 |
10 |
(2)
7 |
18 |
5 |
18 |
1 |
9 |
=
7 |
18 |
5 |
18 |
1 |
9 |
=
1 |
9 |
1 |
9 |
=
2 |
9 |
(3)
5 |
24 |
1 |
4 |
2 |
3 |
=
11 |
24 |
16 |
24 |
=
9 |
8 |
(4)
3 |
4 |
4 |
9 |
1 |
4 |
2 |
9 |
=(
3 |
4 |
1 |
4 |
2 |
9 |
4 |
9 |
=1+
2 |
3 |
=1
2 |
3 |
(5)2-
2 |
7 |
3 |
7 |
=2-(
2 |
7 |
3 |
7 |
=2-
5 |
7 |
=1
2 |
7 |
(6)
3 |
8 |
2 |
7 |
1 |
8 |
5 |
7 |
=(
3 |
8 |
1 |
8 |
2 |
7 |
5 |
7 |
=
1 |
2 |
=1
1 |
2 |
点评:本题考查了分数的加减混合运算,完成本题要注意分析式中数据,运用合适的简便方法计算.
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