Secondary Maths refresh

ceecookie SG

Haha,i need some help here with Secondary Maths.

Well my diploma course requires me to take a prep maths module(since i do not have A Maths),and thing is i never touched my maths books for like - 4 months So i need some help with some of the formulaes lol.

What's the meaning of |a|?As in the two vertical lines

How come it can be put into number lines?And why is it that answer?

Can explain this also?

| x | < 2 = -2 < x < 2 but why not 2 < x < -2?

Very much thanks!

eagle SG

|a| means a is positive.

ie
|2| = 2
|-2| = 2
|3| = 3
|-3| = 3

thus, |x| >= 0 always.

so |x| < 2 is the same as 0<= |x| < 2
if x = -1, |x| = 1 < 2
it is still valid... and so on...

so, -2 < x < 2 will all fit the equation |x| < 2

^tamago^ SG

Your images are not loading, otherwise eagle has provided a good overview of the absolute function.

|x| < 2 = -2 < x < 2 but why not 2 < x < -2? simply because there is no value of x that is larger than 2 AND smaller than -2.

-2 < x < 2 simply means "from -2 to 2, exclusive". the absolute of the numbers within this range is indeed wat we want (absolute or only numerical portion less than 2), e.g. -1, -1.5, 0.5, whose absolutes are 1, 1.5 and 0.5 respectively.

wishboy SG

|a| is also called modulus of a

|| is modulus sign

if |a| = 2, a = -2 or 2

FirePig SG

two vertical lines is called the norm.

http://en.wikipedia.org/wiki/Norm_%28mathematics%29

roughly speaking, it means the "length" of something. There are different norms around such as 1-norm, 2-norm, 3-norm, n-norm, infinity-norm.

hiphop2009 SG

two vertical lines is called the norm.

http://en.wikipedia.org/wiki/Norm_%28mathematics%29

roughly speaking, it means the "length" of something. There are different norms around such as 1-norm, 2-norm, 3-norm, n-norm, infinity-norm.

not too chim for his case...

Darkness_hacker99 SG

The two line thingy..

From what I know.. it stands for magnitude. Can be found in the chapter Vectors.

ceecookie SG

Oh i think i get it now...i think the picture cannot be loaded into the public domain because its part of the poly's webpage that need login.Thanks

eagle SG

Oh i think i get it now...i think the picture cannot be loaded into the public domain because its part of the poly's webpage that need login.Thanks

yup... Checked that before le... but we understand can liao ;)

^tamago^ SG

Oh i think i get it now...i think the picture cannot be loaded into the public domain because its part of the poly's webpage that need login.Thanks

You can save and upload for us mah. :(

ceecookie SG

I understand now that two dash + x means positive and negative x.But then why eagle say only positive results?

|a| should be -a and a right?

Then,how do u determine the answer for negative square root of 3?I only know that 3 cannot be square rooted at all.Lol

singaporeolevelmaths SG

To add on using an example, |3| = 3 or -3 | |==> absolute value of modulus.To put it simply across, the function is that it changes negative numbers to positive

Hanagata SG

omg.....