Help with grasping better problems with negative nymbers

silverpuma · 2013-12-17 19:46:37

Hi all, I'm at Probabilities in my journey and have understood this section on Mathsisfun http://www.mathsisfun.com/multiplying-negatives.html So I have a reasonably good grasp of things so far. But one aspect that I can't see a section on in Mathsidfun and this idea is hurting my wee 1.5 cell brains is things like:

6^2 = 6 x 6= 36

(-6)^2 = -6 x (-6) = 36 (the 2 - negs make a pos)

These 2 examples above I can understand but the next 2 I'm not as clear on, especially the next one.

-6^2 = -36 (I thought that would be -6 x -6 = 36)

(-6)^2 = 36

I know this question is a bit confused but that's because I am a bit confused ....:-) I really need a link to a page that will spell this out for me so I can understand "why" 3rd above is -36 and not 36 as I would have thought.........................thanks for the hand holding and patience!

PS how can I type x squared instead of using the ^ symbol. I notice often you guys used a grayed out image type of text?

bobbym · 2013-12-17 20:05:57

Hi;

There is an order of operations, rules that say which operations come first. That is why the other example had a parentheses around the -6.

When you say -6^2, the squaring is done first and then the minus sign is used.

I really need a link to a page that will spell this out for me so I can understand "why" 3rd above is -36 and not 36 as I would have thought.........................thanks for the hand holding and patience!

Please look here and it will all be clearer:

http://www.mathsisfun.com/operation-order-pemdas.html

http://www.mathsisfun.com/operation-order-bodmas.html

PS how can I type x squared instead of using the ^ symbol. I notice often you guys used a grayed out image type of text?

Do you mean latex ( pronounced lah tek )?

or

x²

How do you like probability so far?

Bob · 2013-12-17 20:16:25

hi silverpuma

It's the brackets that make the difference.

The bracket is telling you do apply the squaring first before the minus (once).

Here, the bracket is telling you to apply the minus first and square that which means two minuses.

PS how can I type x squared instead of using the ^ symbol. I notice often you guys used a grayed out image type of text?

The work above is done using a special code called Latex.

http://www.mathisfunforum.com/viewtopic.php?id=4397

If you click on any Latex expression you'll see how it was constructed. To tell the MIF computer that you want it to apply the Latex you need to enclose the code in square brackets math like this:

Bob

silverpuma · 2013-12-17 22:26:13

Ahhhh the.... "brackets"...... thanks guys! This makes all much clearer. I don't like to move on to another level or section if I'm not comfortable with a question so this is great to receive the help . Simple when you know how ...:-)

@bobbym I have found probabilities perhaps the most difficult to get my head around. But the individual part I've found the hardest so far to feel I grasped fully was the "why does multiplying two negs make a pos". I could follow the rules on the same and different signs ok so could get the right answer (most of the time...!!) but understanding "why" this was so, I found difficult for a while. The balloons example on the mathsidfun site and the: quote:

Example: You owe 3 people $5 each. So you are "Negative 15" (3 × -$5 = -$15).
They then say "we like you so much we forgive the debt" ... you have just had 3 subtractions of -5, so it is like you have added $15 (-3 × -$5 = +$15)."

Was the help I needed to "get" this infused in my bones.......................thanks again guys

PS: I love reading along side the forum and web is there a book on Learning maths you could recommend for me. I'm basically learning with my son as he goes through his Maths lessons trying to keep a little ahead so I can help as best I can. He is year 9 so 2nd year at grammer school and he and I need to arrive at as high a GCSE standard as we can. I mentioned before that his teacher is first class and gives out a small booklet for each term with examples etc that is very well produced and a picture of concise information but I'd like a book to supplement this as I enjoy the learning process.

bobbym · 2013-12-17 22:39:31

Hi;

PS: I love reading along side the forum and web is there a book on Learning maths you could recommend for me.

I have covered hundreds, sometimes emptying out massive shelves of books in the University library. I have never really found anything easier than the MIF pages right over here. I truly mean that. I suggest you keep going through them and copying them.

Books are fine but nothing beats the web for learning. If I would have had the internet and access to this forum when I was just starting out I would be much further along. That is not hype, I am serious. The opportunity to come in and ask a question and get an immediate answer is fantastic. I had to wait years before I found answers to many questions.

Try to go at your own pace. It is much better to know a handful of techniques or concepts thoroughly then to have a smattering of a lot of them.

silverpuma · 2013-12-17 23:24:40

bobbym wrote:

Hi;
PS: I love reading along side the forum and web is there a book on Learning maths you could recommend for me.
I have covered hundreds, sometimes emptying out massive shelves of books in the University library. I have never really found anything easier than the MIF pages right over here. I truly mean that. I suggest you keep going through them and copying them.
Books are fine but nothing beats the web for learning. If I would have had the internet and access to this forum when I was just starting out I would be much further along. That is not hype, I am serious. The opportunity to come in and ask a question and get an immediate answer is fantastic. I had to wait years before I found answers to many questions.
Try to go at your own pace. It is much better to know a handful of techniques or concepts thoroughly then to have a smattering of a lot of them.

I mean this genuinely and no false flattery the MIF site and this forum is my first place to call on when I want to learn a new section on my maths adventure. I love the concise and clear teaching and as you mentioned the help on the forum only accentuate these positives. There may be other more visually slick sites but the content is king in my book.

It amazes me sometimes how the obvious passes me by so often. I discover my blind-spots continuously....! Why didn't I think of copying and printing out the material on the MIF site as you say? Ebay here I come for a batch of cheap ink cartridges......he he.

bobbym · 2013-12-17 23:27:32

Hi;

I save them as html pages and then open them when I am offline in my browser. But make hardcopy if you want and happy reading.

Bob · 2013-12-18 02:10:35

hi silverpuma,

I agree with bobbym that the MIF pages are the best (and they're free!). The interactive pages are just wonderful and everything is cross referenced to make it easy to find what you want.

but I'd like a book to supplement this as I enjoy the learning process.

But, if you want a book that is geared up for the GCSE exam then I would recommend 'Edexcel GCSE Maths Higher Student Book'.

I have to declare an interest: Many years ago I worked in a school with Keith Pledger and he was a great teacher. He went from there to be a head of maths and then got a job with Edexcel as a maths examiner. He then wrote (with others) a series of GCSE maths books. They were very popular in schools as they were clear, had good examples and matched the exam exactly, including the style of question. I haven't seen a better set of books for GCSE maths.

The books have been revised to keep up with changes to the exam. You can also buy it in two parts. Note: Keith hasn't paid me to say any of this!

I see that a well known on-line store will sell you this book. You could probably get the older versions for a good second hand price without losing much as the National Curriculum hasn't changed the content; only the way it is examined has changed.

Bob

silverpuma · 2013-12-18 19:28:53

Thanks Bob for this info and recommendation and I think I'll buy myself a secondhand copy as a gift to myself for Christmas. Some light bedtime reading...............is that sad or what......

silverpuma · 2013-12-18 19:47:06

Bod, hope its OK to post a link but is this the book you mentioned? Its just there seem to be so many variations to choose from I want to make sure I get the right one.

http://www.amazon.co.uk/GCSE-Mathematics-Edexcel-2010-Student/dp/1846900832

How do you post a live link here. Usually I see a "link" button?

Thanks..................

Bob · 2013-12-18 20:28:24

hi silverpuma

There are a lot of variations around, but, I think (hope), they all amount to much the same thing.

The exam board, Edexcel, used to have a couple of GCSE exams, namely the linear and the modular course. But the course content is fixed by the National Curriculum so, in practice, it shouldn't make much difference. Then there are the higher level exam (grades D C B A and A*) and the foundation level exam (grades G F E D and C). Some years ago, there was also an intermediate level. Then there are a lot of smaller practice books (if you find an unexpectedly cheap version, check it is not just a practice book ie. no explanations)

The one I found was £24, so your find is cheaper. Mine had only 5 star reviews; yours has some negative comments*. But I'm fairly sure you'll find all you need in your one in spite of this.

*Some say some answers are wrong. That seems to happen with most text books ... or maybe the reader was wrong ??? Anyway, if you try a question and don't get the book answer, post it to MIF and we'll take a look.

Is it sad to have this for light bedtime reading? Certainly not! I'm not fully awake until about 2200. Happy reading.

Bob

ps.

[url]web address[/url]

Last edited by Bob (2013-12-18 20:43:53)

Math Is Fun Forum

#1 2013-12-17 19:46:37

Help with grasping better problems with negative nymbers

#2 2013-12-17 20:05:57

Re: Help with grasping better problems with negative nymbers

#3 2013-12-17 20:16:25

Re: Help with grasping better problems with negative nymbers

#4 2013-12-17 22:26:13

Re: Help with grasping better problems with negative nymbers

#5 2013-12-17 22:39:31

Re: Help with grasping better problems with negative nymbers

#6 2013-12-17 23:24:40

Re: Help with grasping better problems with negative nymbers

#7 2013-12-17 23:27:32

Re: Help with grasping better problems with negative nymbers

#8 2013-12-18 02:10:35

Re: Help with grasping better problems with negative nymbers

#9 2013-12-18 19:28:53

Re: Help with grasping better problems with negative nymbers

#10 2013-12-18 19:47:06

Re: Help with grasping better problems with negative nymbers

#11 2013-12-18 20:28:24

Re: Help with grasping better problems with negative nymbers

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