高一數學問題 請高手指導拜託..

1. |2X-1| |X-5| - |X-7| = 15 之解為? 代數解法:2. X.Y為實數

|X-1|≦2

|y-3|≦2

求X/Y的範圍為?3. a=622/733 b=833/944 c=432/543 比較abc大小
1.|2x - 1| |x - 5| - |x - 7| = 15情況一： 當 x ≤ 1/2-(2x - 1) [-(x - 5)] - [-(x - 7)] = 15-2x 1 - x 5 x - 7 = 152x = -16x = -8情況二：當 1/2 ≤ x ≤ 5(2x - 1) [-(x - 5)] - [-(x - 7)] = 152x - 1 - x 5 x - 7 = 152x = 18x = 9但 x= 9 不在 1/2 ≤ x ≤ 5 的範圍

故情況二無解。

情況三：當 5 ≤ x ≤ 7(2x - 1) (x - 5) - [-(x - 7)] = 152x - 1 x - 5 x - 7 = 154x = 28x = 7情況四：當 x ≥ 7(2x - 1) (x - 5) - (x - 7) = 152x - 1 x - 5 - x 7 = 152x = 14x = 7答案：x = -8 或 x = 7=====2.|x - 1| ≤ 2-2 ≤ (x - 1) ≤ 2-1 ≤ x ≤ 3|y - 3| ≤ 2-2 ≤ y - 3 ≤ 21 ≤ y ≤ 5x/y 的最小值 = -1/1 = -1x/y 的最大值 = 3/1 = 3答案： -1 ≤ x/y ≤ 3=====3. a = 622/733 = (733 - 111)/733 = 1 - (111/733)b = 833/944 = (944 - 111)/833 = 1 - (111/833)c = 432/543 = (543 - 111)/543 = 1 - (111/543)111/833