问题 解答题
脱式计算.
5
9
×[1÷(
7
8
-
3
4
)]
1.25×32×2.5
(3.8-1.8÷2)×0.5
7
15
×9-6÷
15
7
答案

(1)

5
9
×{1÷(
7
8
-
3
4
)}

=

5
9
×{1÷(
21
24
-
18
24
)}

=

5
9
×{1÷
1
8
}

=

5
9
×8

=4

4
9

(2)1.25×32×2.5

=(1.25×8)×(4×25)

=10×100

=1000;

(3)(3.8-1.8÷2)×0.5

=(3.8-0.9)×0.5

=2.9×0.5

=1.45;

(4)

7
15
×9-6÷
15
7

=

7
15
×9-6×
7
15

=

7
15
×(9-6)

=

7
15
×3

=

7
5

=1

2
5

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