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bobbym
2013-02-25 22:52:17

Hi;

I'm trying to make sense of the pages that I DO have.

That is always true. Math is huge, you will always be missing most of the jigsaw puzzle pieces. Thinking mathematically means thinking without all the pieces.

Because an absolute value is always positive, when you put a big negative sign in front of it, it will be negative. Want to do a few right now. Best way to learn is by example.

zetafunc.
2013-02-25 22:50:15

Absolute values are always positive. The minus sign then makes it negative. So the negative of any absolute value is negative.

MargaritaMc
2013-02-25 22:47:55

Yes, normally I agree absolutely with that - and perhaps that is what is motivating me now.

But sometimes I just can't find the beginning of the thread of reasoning. It is as tho some pages have been left out of a book and I'm trying to make sense of the pages that I DO have.

For example. This is one of the info sites I referred to this morning. I've highlighted the bits that utterly confused me.

Double-you•3.purplemath.com/modules/absolute.htm

The absolute value of x, denoted "| x |" (and which is read as "the absolute value of x"), is the distance of x from zero. This is why absolute value is never negative; absolute value only asks "how far?", not "in which direction?" This means not only that | 3 | = 3, because 3 is three units to the right of zero, but also that | –3 | = 3, because –3 is three units to the left of zero.

But a few lines further on it says,

It is important to note that the absolute value bars do NOT work in the same way as do parentheses. Whereas –(–3) = +3, this is NOT how it works for absolute value:

Simplify –| –3 |.
Given –| –3 |, I first handle the absolute value part, taking the positive and converting the absolute value bars to parentheses:

–| –3 | = –(+3)

Now I can take the negative through the parentheses:

–| –3 | = –(3) = –3

As this illustrates, if you take the negative of an absolute value, you will get a negative number for your answer.

Huh?!

Margarita

bobbym
2013-02-25 22:11:45

but really feel quite stressed-out at this hit-and- miss way that I am staggering around maths learning.

I find that is the best way to learn. Maybe you are the same way? Learning whenever the need to arises keeps you motivated and hungry. It does not matter how advanced or simple the topic is rated as. If you want it and need it right now you will learn it.

Rated courses are a failure. First algebra, then trig then some geometry then some... 90% of the world hates math. Those ratings of hard and easy were put there by guys who have been dead for 300 years.

Trust the force, Luke!

Let your desire and intuition guide you as to the order. You will learn at your own pace and you will have more fun.

MargaritaMc
2013-02-25 22:03:33

As I said back in my introduction, I am at a basic level in maths and don't have access to a tutor.

There is masses of info on the web, but I'm discovering that I am sometimes dropped into a topic that I haven't had the lead-up to.

Today that was 'absolute values', on Khan Academy.

I found an explanation of what this is on the Maths is Fun site, by using Google, but really feel quite stressed-out at this hit-and- miss way that I am staggering around maths learning.

Can anyone recommend a list of topic areas to cover IN ORDER?
This would need to be right from basic-basics, just so that I can check the foundations before I try to move on.

I've just bought 'Basic Maths for Dummies' by Colin Beveridge, so it may help.

But - I would REALLY appreciate some advice on the order in which I would best tackle topics.

Margarita