2,3,7,9四个数字列出6个算式使得数为24

急急急 明天就上课了!!!!

第1个回答  2012-10-17
  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)追问

谢谢 但是我需要的是得数为24的6个算式
3×8思路
2×12思路
48÷2思路
15+9思路
3÷1/8思路
3/2×16思路

追答

  这些都是得数24啊;
  3 × [(9 + 7) ÷ 2]=3*(16/2)=3*8=24
  2 × (3 × 7 - 9)=2*(21-9)=2*12=24
  3 × (7 + 9) ÷ 2=3*16/2=48/2=24
  (7 - 2) × 3 + 9=5*3+9=15+9=24
  3 ÷[(2 ÷ (7 + 9)]=3/(2/16)=3/(1/8)=3*8=24
  3 ÷ 2 ×(7 + 9)=(3/2)*16=3*8=24

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