F.4 Absolute value

1
absolute value 係永遠都會係 正數
|-4| = (-4)(-1) =+4
|10|=10
2
是會有2 answers
for
|m+4| =3
m+4=3 or -3
m=-1 or -7
for
|m+4|>3
m+4>3 or m+4<-3
m>-1 or m<-7

1.加左absolute sign (兩棟) 一定係正數..
如果係加左absolute sign 既vector就即係佢既magnitude (到vector果課會教)

2.solve 呢類problems 要分cases.
睇多d書既example應該會明

2007-01-02 08:11:23 補充：
即係 |x|=10case 1) x=-10case 2) x= 10