a0a得兩題渣渣渣渣

1.
Since the equation has two unequal real roots, the discriminant of the quadratic equation > 0.

(6)^2 - 4(k)(3) >0
36 - 12k > 0
-12k > - 36
k < 3 (Pay attention to the change in inequality sign)

2.
因為問題並沒有寫清楚border的area, 我不知怎樣答. 對不起.

[題外話: 我之前有個post已經答了一次, 謝謝! http://hk.knowledge.yahoo.com/question/?qid=7007120500210]

2007-12-06 00:16:47 補充：
補充上面:[Set 1]2.我找到你的問題出處了.(a)Length of the frame = (30 + 2x) cmWidth of the frame = (20 + 2x) cm(b)(30+2x)(20+2x) - (30)(20) = 1594x^2 + 100x + 600 - 600 = 1594x^2 + 100x - 159 = 0(2x-3)(2x+53) = 0x = 3/2 or x = -53/2 (rejected)

2007-12-06 21:08:23 補充：
159是題目給的. 你的圖像並沒有顯示, 我是從別處找到跟你題目一樣的.