請幫幫忙，有條問題唔知應該點做

As follows:

圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/01-124.jpg


2010-07-14 14:47:49 補充：
http://i707.photobucket.com/albums/ww74/stevieg90/01-124.jpg

(x+2)(x-4)=(a+2)(a-4)
x^2-2x-8.=a^2-2a-8
x^2-a^2...=2(x-a)
(x+a)(x-a)=2(x-a)
(x+a)........=2
x.............=2-a

其實你如果THINK清楚條題目,a=x...............

..................x=2-x
............2x....=2
.................x.=1

(x+2)(x-4)=(a+2)(a-4)

x^2 + 2x - 4x - 8 = a^2 + 2a - 4a - 8

x^2 - 2x = a^2 - 2a

x^2 - a^2 - 2x + 2a = 0

(x - a)(x + a) - 2(x - a) = 0

(x - a)(x + a - 2) = 0

x = a or x = 2 - a