A.math...past paper

依個係Joint Us 本solution既解釋,我就自己再加D中文解一解,你睇下明唔明啦
(我打唔到-細過或等如-個符號~~~>=~~咁樣代表住先啦)

f(x)<=g(x)
x2-2x-6<=2x+6
x2-4x-12<=0
(x-6)(x+2)<=0
-2<=x<=6

(上part計左當x=6, y=18,同當x=-2, y=2
所以when -2<=x<=6, 2<=y<=18
而 係y=k依條 equation,,sub番y個range落黎
2<=k<=18就係答案

但係除此以外,係f(x) 既vertex, y=-7
所以當y=k=-7,,亦都係得一個intersection
所以 k=-7 亦都係答案)

Therefore the range of values of k such that the equation f(x)=k has only one real root is 2<=k<=18 and k=-7


一般書店應該冇可能一次過買到成本二十年既past paper,,
要逐年買,,不過03之前既past paper就有成本十幾年既
但係已經冇出，要去舊書店買
或者你可以上網downloador 問老師借黎印
solution 就有成本29年, joint us 出既
好多書店都有

商務,三聯,大眾!你問一下店員,一本本的!