问题 解答题
计算:
(1)
2
5
÷(-2
2
5
)-
8
21
×(-1
3
4
)-0.5÷2×
1
2

(2)-5-[(-2)3+(1-0.8×
3
4
)÷(-2)]

(3)-0.52+
1
4
-|-22-4|-(-1
1
2
)3×
16
27
答案

(1)

2
5
÷(-2
2
5
)-
8
21
×(-1
3
4
)-0.5÷2×
1
2

=

2
5
×(-
5
12
)+
8
21
×
7
4
-
1
2
×
1
2
×
1
2

=-

1
6
+
2
3
-
1
8

=

3
8

(2)-5-[(-2)3+(1-0.8×

3
4
)÷(-2)]

=-5-[-8+(1-0.6)÷(-2)]

=-5-[-8+0.4÷(-2)]

=-5-[-8-0.2)]

=-5+8.2

=3.2;

(3)-0.52+

1
4
-|-22-4|-(-1
1
2
)3×
16
27

=-

1
4
+
1
4
-|-4-4|+
27
8
×
16
27

=-8+2

=-6.

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