| 这个比较难 |
| 送交者: 零加一中 2019月02月11日18:49:04 于 [灵机一动] 发送悄悄话 |
| 回 答: 趣味的数学 - 5 由 gugeren 于 2019-02-10 09:32:29 |
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Use AA for the car starts from A. The other car is BB. Set number axis as A = 0 and B = 1. When BB first arrives A (x=0), AA has reached A and come back at x=3/4. Then they meet (second time) at x=1/3 (145 km). When BB backs to B (x=1), AA is at x = ½. Then they meet (third time) at x = 7/9 (201 km). Therefore, 4/9 = 56 km and 1/9 = 14 km. A = 145 – 42 = 103 km B = 201 + 28 = 229 km |
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