问题 解答题
怎样算简便就怎样算.
4
9
×
1
5
÷
4
5
(15-14×
4
7
)×
8
21
4
5
÷[(
1
3
+
2
5
)×
4
11
];
1
8
×58+42÷8;
7
2
×
5
8
-
3
2
÷
8
5
3
4
×40%+0.75×
3
5
答案

(1)

4
9
×
1
5
÷
4
5

=

4
9
×
1
5
×
5
4

=

1
9

(2)(15-14×

4
7
)×
8
21

=(15-8)×

8
21

=7×

8
21

=

8
3

(3)

4
5
÷[(
1
3
+
2
5
)×
4
11
]

=

4
5
÷[
11
15
×
4
11
]

=

4
5
÷
4
15

=

4
5
×
15
4

=3

(4)

1
8
×58+42÷8

=

1
8
×58+42×
1
8

=

1
8
×(58+42)

=

1
8
×100

=12.5

(5)

7
2
×
5
8
-
3
2
÷
8
5

=

7
2
×
5
8
-
3
2
×
5
8

=(

7
2
-
3
2
)×
5
8

=2×

5
8

=

5
4

(6)

3
4
×40%+0.75×
3
5

=

3
4
×
2
5
+
3
4
×
3
5

=

3
4
×(
2
5
+
3
5

=

3
4
×1

=

3
4

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