Math Equation DEBATE

arz15

/m

(edited 12 years ago)

Reply 1

Miss Anonymous

9

http://www.thestudentroom.co.uk/showthread.php?t=1599924

Reply 2

nuodai

17

We had one too: http://www.thestudentroom.co.uk/showthread.php?t=1599924

And it's now locked, because it just descended into people squabbling. Some people think it's 2, some think it's 288 and some people think that it's ambiguous. There was a big tendency for people without much training in maths to have a very strong opinion about it 'definitely' being 2 or 288, and for the people who have a more advanced training in maths to say that it's ambiguous. Go figure.

Please don't start this again :s-smilie:

Reply 3

I'm clever

6

Original post by nuodai

We had one too: http://www.thestudentroom.co.uk/showthread.php?t=1599924

And it's now locked, because it just descended into people squabbling. Some people think it's 2, some think it's 288 and some people think that it's ambiguous. There was a big tendency for people without much training in maths to have a very strong opinion about it 'definitely' being 2 or 288, and for the people who have a more advanced training in maths to say that it's ambiguous. Go figure.

Please don't start this again :s-smilie:

Surely a simple maths calculation like that shouldn't be ambiguous? I know nothing about maths, but follow BIDMAS and you get either 2 OR 288. There shouldn't be 2 answers. Maths is about finding the right answer.

Reply 4

nuodai

17

Original post by I'm clever

Surely a simple maths calculation like that shouldn't be ambiguous? I know nothing about maths, but follow BIDMAS and you get either 2 OR 288. There shouldn't be 2 answers. Maths is about finding the right answer.

It shouldn't be ambiguous, no, but it's not a simple maths calculation, it's an ambiguous representation. It's bad maths, so you can't expect to have a right answer. Similarly if I wrote 18÷6÷3 it wouldn't be clear if I meant 1 or 9, and if I wrote

^2 \times 3 / 6 _4 \times 2+

it wouldn't mean anything at all. Maths is about finding the right answer when the question makes sense, but here the question doesn't make sense.

EDIT: And FWIW you can't apply BIDMAS to this unless you know whether the 9+3 is on the numerator or denominator. There's an implicit bracket either around (48/2) or around (2(9+3)); it has to be one or the other, and so when you apply BIDMAS you have to decide which it is. It's not clear from the notation which it is, and so even using BIDMAS it's ambiguous.

Anyway I said enough about this in the other thread, if you can be bothered to read through it I recommend you do... then you'll see why it's not worth having this 'debate' again.

(edited 13 years ago)

Reply 5

arz15

OP

Original post by nuodai

We had one too: http://www.thestudentroom.co.uk/showthread.php?t=1599924

And it's now locked, because it just descended into people squabbling. Some people think it's 2, some think it's 288 and some people think that it's ambiguous. There was a big tendency for people without much training in maths to have a very strong opinion about it 'definitely' being 2 or 288, and for the people who have a more advanced training in maths to say that it's ambiguous. Go figure.

Please don't start this again :s-smilie:

Oh wow, I thought it was just there! LOL

Reply 6

I'm clever

6

Original post by nuodai

It shouldn't be ambiguous, no, but it's not a simple maths calculation, it's an ambiguous representation. It's bad maths, so you can't expect to have a right answer. Similarly if I wrote 18÷6÷3 it wouldn't be clear if I meant 1 or 9, and if I wrote

^2 \times 3 / 6 _4 \times 2+

it wouldn't mean anything at all. Maths is about finding the right answer when the question makes sense, but here the question doesn't make sense.

Surely it's logical to work from left to right so the answer would be 1, not 9. Why on earth would you do 6÷3 = 2 , then 18 ÷2 = 9? That doesn't seem logical to me. :confused:

Reply 7

nuodai

17

Original post by I'm clever

Surely it's logical to work from left to right so the answer would be 1, not 9. Why on earth would you do 6÷3 = 2 , then 18 ÷2 = 9? That doesn't seem logical to me. :confused:

This was sort of my point by the whole people without much training in maths vs people with training in maths thing; for some reason the people without much training in maths think it's "surely totally logical" to make up these arbitrary rules, leading them to think that {insert 2 or 288 here} is definitely completely absolutely the right answer and everyone else is wrong. But it's not logical, it's arbitrary. There's no mathematical law that says you have to work from left to right or so on; in unambiguous notation it makes no difference which side you work from. And that's the point -- notation is there to make it clear what we mean, not to skew the meaning and then bring the need to apply contrived rules to work the meaning out.

(edited 13 years ago)

Reply 8

Ivanka

16

It's not ambiguous, it depeneds on whether it is actually 48/[2(9+3)] or (48/2)(9+3) and in this respect the original equation seems illegible.

Reply 9

nuodai

17

Original post by Ivanka

It's not ambiguous, it depeneds on whether it is actually 48/[2(9+3)] or (48/2)(9+3) and in this respect the original equation seems illegible.

So what you're saying is that it's ambiguous :p:

Reply 10

Boom Boom Pow

13

Lets not start this again...

Reply 11

I'm clever

6

Original post by nuodai

It shouldn't be ambiguous, no, but it's not a simple maths calculation, it's an ambiguous representation. It's bad maths, so you can't expect to have a right answer. Similarly if I wrote 18÷6÷3 it wouldn't be clear if I meant 1 or 9, and if I wrote

^2 \times 3 / 6 _4 \times 2+

it wouldn't mean anything at all. Maths is about finding the right answer when the question makes sense, but here the question doesn't make sense.

EDIT: And FWIW you can't apply BIDMAS to this unless you know whether the 9+3 is on the numerator or denominator. There's an implicit bracket either around (48/2) or around (2(9+3)); it has to be one or the other, and so when you apply BIDMAS you have to decide which it is. It's not clear from the notation which it is, and so even using BIDMAS it's ambiguous.

Anyway I said enough about this in the other thread, if you can be bothered to read through it I recommend you do... then you'll see why it's not worth having this 'debate' again.

Ok if YOU had to give an answer, would you give 2 or 288?

Reply 12

Haddock3

Oh sweet lord, not again.

Reply 13

arz15

OP

lool, our thread is at like 90 pages now :frown:

The site creator is saying 288 while I think it's 2, along with a few others.

Reply 14

W.H.T

15

I've always been taught to work out what's inside the brackets first and then do the rest of the equation, so for this I'll get 2 :smile:

Reply 15

nuodai

17

Original post by I'm clever

Ok if YOU had to give an answer, would you give 2 or 288?

I'd say it's "2 if 9+3 is in the denominator, or 288 if it's in the numerator". And without context we don't know which it's in.

Asking me to decide whether it's 2 or 288 is the same as asking me any of these questions:

- You have a bag with a red ball and a blue ball in it. You put your hand in and pull out one of these ball at random. Is the ball you pull out red or blue?

- You toss a fair coin. Does it show heads or tails?

- You jump out of a first floor window and have a 50% chance of living and a 50% chance of dying, and you have no choice over either outcome. Do you live or die?

I hope you can see why it's silly to give one or the other as an answer. The answer isn't "both", and there aren't 2 answers; instead, there is no well-defined answer, and there are two possible answers. The actual answer can't be determined without more context and, here, we have no more context, so no matter how much you argue about which answer it is, you're going to get nowhere.

Original post by W.H.T

I've always been taught to work out what's inside the brackets first and then do the rest of the equation, so for this I'll get 2 :smile:

...if the bracket's on the denominator. There's no reason why you should distribute just the "2" over the bracket rather than the "48/2". The former gives 2 and the latter gives 288. Like I say, BIDMAS doesn't remove ambiguity here.

EDIT:

DFranklin

.

Please! Make it stop!

(edited 13 years ago)

Stop it.........

Original post by nuodai

...if the bracket's on the denominator. There's no reason why you should distribute just the "2" over the bracket rather than the "48/2". The former gives 2 and the latter gives 288. Like I say, BIDMAS doesn't remove ambiguity here.

EDIT: Please! Make it stop!

Can you show what you mean by this?

I'm slightly confused by the wording :tongue:

Reply 18

nuodai

17

Original post by W.H.T

Can you show what you mean by this?

I'm slightly confused by the wording :tongue:

Okay sure. "Distribution" is what happens when you write

a(b+c)=ab+ac

, we say that multiplication is "distributive" over addition.

Here, we have one of two possible cases. In one case we have

\dfrac{48}{2(9+3)}

, in which case 2 distributes over the bracket and we get 2. In the other case, we have

\dfrac{48}{2}(9+3)

, in which case

\frac{48}{2}

distributes over the bracket and we get 288. It's not clear from the notation which it is meant to be.

Reply 19

Slumpy

16

Original post by W.H.T

Can you show what you mean by this?

I'm slightly confused by the wording :tongue:

Distributivity, ie a(b+c)=ab+ac
So he's saying there's no reason we distribute just the 2(getting 2*12 on the bottom), or the 48/2.

Math Equation DEBATE

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