问题 解答题
用递等式计算(能简便计算的要写出简算过程).
①[3.2×(1-
5
8
)+3
3
5
]×2
1
12
②1
3
7
+2
4
15
+4
4
7
+3
2
15
43
97
×99
④3.75×4
2
5
+1.6×3
3
4
⑤1÷2.5+2.5×0.4⑥3
2
5
-1
3
4
-
1
4
答案

①[3.2×(1-

5
8
)+3
3
5
]×2
1
12

=[3

1
5
×(1-
5
8
)+3
3
5
]×2
1
12

=[3

1
5
×
3
8
+3
3
5
]×2
1
12

=(

6
5
+
18
5
)×
25
12

=

24
5
×
25
12

=10;

②1

3
7
+2
4
15
+4
4
7
+3
2
15

=(1

3
7
+4
4
7
)+(2
4
15
+3
2
15
),

=6+5

2
3

=11

2
3

43
97
×99,

=

43
97
×(97+2),

=

43
97
×97+
43
97
×2,

=43+

86
97

=43

86
97

④3.75×4

2
5
+1.6×3
3
4

=3.75×4.4+1.6×3.75,

=3.75×(4.4+1.6),

=3.75×6,

=22.5;

⑤1÷2.5+2.5×0.4,

=0.4+2.5×0.4,

=0.4×(1+2.5),

=0.4×3.5,

=1.4;

⑥3

2
5
-1
3
4
-
1
4

=3

2
5
-(1
3
4
+
1
4
),

=3

2
5
-2,

=1

2
5

单项选择题
单项选择题