please could someone help me get and understand this maths question?

[ssd]

thanks, cant work it out at all

solve.

3a=3a-6 and a
... ....... ...
4 2 3


(the ... is meant to be a line, the "and" is a plus sign)

thanks

[schobe]

Ahem

[Toomanyworriedsonhere]

okay okay schobe did it first but AMumInScotland's solution is closest to the end of the thread.

SCHOBE DID IT FIRST

[ssd]

i appreciate muminscotlands answer, but I cant follow it

why is it not 12 X 3a instead of 3ax12/4? from the second line

yes am thick

[ssd]

I cant do lines on this pc thats why i cant show it as its written,but can anyone write it out as an aswer, i might get that a bit more

[schobe]

Entirely unnecessary Toomany but good of you to say.



ssd - if you multiply 3a/4 by 12, it's 3 x a / 4 x 12 (read / as divided by).

You can do the string in any order as long as the divide stays just before the 4.

So put 3 x 12 / 4 x a. Do it a bit at a time.

36 / 4 x a (I did 3 x 12)
9 x a (I did 36 / 4)
ie 9a.

Any help?

[ssd]

at the end why did we take away 9a and then add 36 to each side?

[schobe]

Ok we had 9a = 22a - 36 at that point

take away 9a from each side (then that gets rid of the 9a on the left side and you've only got 'a's on one side) -
0 = 13a - 36

add 36 to each side (this gets rid of the minus 36 on the right side so that you're just left with 13a on its own, nice and simple) -
36 = 13a

divide both sides by 13 -
36/13 = a

I think tackling a much easier equation might be a better option at this point to firm up the basics. If your DC is lost as well, the teacher needs to talk it through with them and set something more appropriate.

[noarguments]

This is hilarious!
MN is diversifying into Maths lessons!

[CumbernauldMathsTutor]

If the question has been written correctly, a=36/13.

But age 13 homework would not have such an answer!

I think there is a mistake in the question.

[ssd]

thanks, i think (hope) he gets it now, have just spent 2 hours trying to study with him, he is getting answers right, I'm doodling along at the side.............

[CumbernauldMathsTutor]

Maryz Wed 05-Oct-11 22:16:17:

"Age 13 homework could easily end with 36/13 which equals 2 and 10/13. ds is doing loads of these atm."



Maryz, I would be interested to know in which school an age 13 homework question in algebra could easily end with a fraction like 36/13 as an answer.

[bossboggle]

OMG OMG!! Brain frazzled!!

[CumbernauldMathsTutor]

Maryz, yes please post a couple of questions here and also give the name of the school text book they come from.

[schobe]

Sounds like CubernauldMathsTutor favours the unrealistic, sanitised approach I mentioned earlier where all answers are nice tidy round numbers. Traditional text books in England have long favoured this and it really encourages a lack of confidence in potentially very able mathematicians.

Firstly, they are used to having answers in the back of the book and can't trust their own methods without 'checking'. Secondly, if the answer is not 'nice' they again can't trust their own methods because they are so used to text book 'nice' answers. I really hate it.

Good thing your DC's school is doing something a bit better Maryz.

[schobe]

And before anyone leaps on my reference to 'round numbers', I don't mean whole numbers. They could be rational or irrational, but have a tendency to be 'neat'.

[nickelbabe]

schobe - exactly, that's something that our a-level maths teacher used to drum into us.

[ssd]

i think cumbernauldmathstutor is in scotland, as i am

when i went to WHSmiths to try to get a maths book to help methere was none available, just gcse stuff which i imagine is for older kids

cumbernauld which books would you recommend, if any?

[ssd]

oh no maryz, thank god for the answers, ds's teacher never seems to mark his homework or explain where he goes wrong, so the answers are valuable for thickos like me to check we're getting the right answers

does you ds use any online websites to help him that I could use with ds?

or does he just ask his brainy mum

[RunAwayHome]

I really liked having answers in the book (North America) - children I teach here are often really surprised, and can't believe we wouldn't have just cheated. But it was a totally different attitude to homework - here they see it as something the teacher makes them do, that they have to get finished, and preferably get the right answer, to get the ticks. For us, it was a way of checking that we understood the topic - if you weren't getting them right, you knew there was something wrong that you'd better sort out before going on to anything new, and because you were going to need to be able to do those questions for an upcoming exam. It was very much seen as our responsibility, not the teachers'. If you knew that you knew the work, you didn't have to do it, either. Or if you'd been assigned just the odd numbered problems, for example, and were getting them wrong, then you knew you'd better try the even ones as well until you got to the point where you were doing it successfully. That was what mattered more than anything else - knowing for yourself that you were at the point where you understood it well enough for exams/future work, and whether you needed help on it from the teacher. We all knew that there'd be no point just copying the answers from the book, since that wasn't the reason for doing homework. In fact, the teacher rarely ever took in the books or corrected it; the exams spoke for themselves. She might have wandered around looking at what had been done, to see how people were getting on with it, whether any common problems cropped up, etc., but that was it. I quite liked that sense of responsibility on the pupils to master something, to do as much or as little as they felt they needed to be able to do it.

But we were an advanced set, and it was quite a competitive school and we all wanted to do well on exams, which I'm sure made a difference.

I hate books that don't have answers, though, as it removes that responsibility from the children.