用有理数算24点用2、3、7、9来算,列举三种

1:2 × (3 × 7 - 9)
2:2 × ((3 × 7) - 9)
3:2 × (7 × 3 - 9)
4:2 × ((7 × 3) - 9)
5:3 ÷ 2 ×(7 + 9)
6:(3 ÷ 2) × (7 + 9)
7:3 ÷ (2 ÷ (7 + 9))
8:3 ÷ 2 ×(9 + 7)
9:(3 ÷ 2) × (9 + 7)
10:3 ÷ (2 ÷ (9 + 7))
11:(3 × (7 - 2)) + 9
12:3 × (7 - 2) + 9
13:(3 × (7 + 9)) ÷ 2
14:3 × (7 + 9) ÷ 2
15:3 × ((7 + 9) ÷ 2)
16:(3 × 7 - 9) × 2
17:((3 × 7) - 9) × 2
18:(3 × (9 + 7)) ÷ 2
19:3 × (9 + 7) ÷ 2
20:3 × ((9 + 7) ÷ 2)
21:(7 - 2) × 3 + 9
22:((7 - 2) × 3) + 9
23:(7 × 3 - 9) × 2
24:((7 × 3) - 9) × 2
25:(7 + 9) ÷ 2 × 3
26:((7 + 9) ÷ 2) × 3
27:(7 + 9) ÷ (2 ÷ 3)
28:(7 + 9) × 3 ÷ 2
29:((7 + 9) × 3) ÷ 2
30:(7 + 9) × (3 ÷ 2)
31:9 - (2 - 7) × 3
32:9 - ((2 - 7) × 3)
33:9 - (3 × (2 - 7))
34:9 - 3 ×(2 - 7)
35:9 + (3 × (7 - 2))
36:9 + 3 ×(7 - 2)
37:9 + (7 - 2) × 3
38:9 + ((7 - 2) × 3)
39:(9 + 7) ÷ 2 × 3
40:((9 + 7) ÷ 2) × 3
41:(9 + 7) ÷ (2 ÷ 3)
42:(9 + 7) × 3 ÷ 2
43:((9 + 7) × 3) ÷ 2
44:(9 + 7) × (3 ÷ 2)

2 × (3 × 7 - 9)
3 × (7 + 9) ÷ 2
9 + (7 - 2) × 3