Absolute Values

As follow AS~~~~

圖片參考：http://e.imagehost.org/0194/ScreenHunter_03_Dec_25_20_23.gif



2008-12-25 23:08:47 補充：
更改小小~
http://e.imagehost.org/0880/ScreenHunter_05_Dec_25_23_07.gif

Let y＝ x－2
Then (x－2)^2 －5│x－2│－ 6＝20 becomes:
y^2－5y－26＝0

Using root＝ －b +/－ sqrt(b^2－4ac) to solve:
y＝ 5 +/－ sqrt(25－4(1)(－26)) ＝5 +/－sqrt(129)
So, y = 8.1789 or y= －3.1789

Remember y= x－2 > 0
Therefore, y has to be 8.1789 and x = 8.1789+2 = 10.1789

2008-12-25 20:26:31 補充：
There are typos in the middle of the solution. I forget to type the "2" in the denominator.

The correct version:
Using root＝ [－b +/－ sqrt(b^2－4ac)]/2 to solve:
y＝ [5 +/－ sqrt(25－4(1)(－26))]/2 ＝2.5 +/－sqrt(129)/2