问题 解答题
运用你学过的方法算
1
2
5
-0.25+
7
20
3
5
×7
3
5
+3
2
5
×
3
5
-0.6
1
4
+1÷
2
7
)÷2
1
7
1
6
+
3
8
)×12×24
1
2
3
÷[(2
5
6
-1
2
3
)×
2
7
+
1
3
].
答案

(1)1

2
5
-0.25+
7
20

=1.4-0.25+0.35,

=1.15+0.35,

=1.5;

(2)

3
5
×7
3
5
+3
2
5
×
3
5
-0.6,

=

3
5
×7
3
5
+3
2
5
×
3
5
-
3
5
×1,

=

3
5
×(7
3
5
+3
2
5
-1),

=

3
5
×(11-1),

=

3
5
×10,

=6;

(3)(

1
4
+1÷
2
7
)÷2
1
7

=(

1
4
+
7
2
)×
7
15

=

15
4
×
7
15

=

7
4

(4)(

1
6
+
3
8
)×12×24,

=(

1
6
+
3
8
)×24×12,

=(

1
6
×24+
3
8
×24)×12,

=(4+9)×12,

=4×12+9×12,

=48+108,

=156;

(5)1

2
3
÷[(2
5
6
-1
2
3
)×
2
7
+
1
3
],

=1

2
3
÷[1
1
6
×
2
7
+
1
3
],

=1

2
3
÷[
7
6
×
2
7
+
1
3
],

=1

2
3
÷[
1
3
+
1
3
],

=

5
3
÷
2
3

=

5
2

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