What is the answer to 48/2(9+3)?

[MisterD]

Poll results show that is the intuitive response for only 46.91% of participants,

Er no. Poll results show no such thing...I'd venture to suggest that the whole point of how this argument works is the conflict between intuitive and counter-intuitive application of "BODMAS" and a L-R reading.

[bogan]

Er no. Poll results show no such thing...I'd venture to suggest that the whole point of how this argument works is the conflict between intuitive and counter-intuitive application of "BODMAS" and a L-R reading.

I made the assumption that everyone answered with their intuitive interpretation, just because it isn't intuitive for you, doesn't mean it can't be intuitive for others. Shit this is getting more like the scottish thread now

[BoristheBiter]

But still heaps easier than the scottish thread!

But twice as boring.

[marie_speeds]

ok, if i didn't know the equation I would just process it left to right, as per bodmas without 'implicit brackets', which I can't find reference to in any mathematical texts, got a link to that?

What has struck me as funny about this thread is the fact that you guys depend so heavily on wiki and other links to justify your responses. Where as those of us erm older generation types who left school ages ago have relied only on what we have learnt all those years ago. I am currently in the process of writing my master's thesis, if I handed in a draft to my supervisor with a Wiki link reference to justify my research, no doubt I would be bitch slapped, made to eat my draft and then promptly kicked out of the office and told never to come back. No link....use your head same rules as applied to OP.

[MisterD]

I made the assumption that everyone answered with their intuitive interpretation, just because it isn't intuitive for you, doesn't mean it can't be intuitive for others. Shit this is getting more like the scottish thread now

Assumption is what....?

Anyhoo, over at Physics Forums answer '2' is winning.

[bogan]

What has struck me as funny about this thread is the fact that you guys depend so heavily on wiki and other links to justify your responses. Where as those of us erm older generation types who left school ages ago have relied only on what we have learnt all those years ago. I am currently in the process of writing my master's thesis, if I handed in a draft to my supervisor with a Wiki link reference to justify my research, no doubt I would be bitch slapped, made to eat my draft and then promptly kicked out of the office and told never to come back. No link....use your head same rules as applied to OP.

Wiki is useful to clarify what you know, I too am writing thesis, (which is fucking boring so I find myself here instead) and would not use it as a reference, but when I can't remember a certain equation or need an algorithm template or whatever, wiki is a nice standardized generally reliable place to get it, unlike some old fogeys memory

However the point of providing references in any work, is to show you know the subject matter, and to back up your assertions, try submitting you thesis and telling them you just used you head instead of referencing things

So again, if you have any link to show your interpretation is more than just your interpretation

I mean c'mon, maths is a fairly exact science, if an equation can give two different answers with a 50/50 split depending on the interpretation, it has to be the equation writer that is wrong? surely everyone can see that

Assumption is what....?

required when there is ambiguity

[pzkpfw]

Xc=1/2pifC (written as a single line short hand equation just like op)

where f=50 hertz and C=80micro Farads
So Xc=?

Get it wrong and I suggest you change majors....LOL....Get it right and it means that you are using double standards when solving single line short hand equations to justify your answer by inserting brackets where none is shown LOL

Nah, that's still just nasty shorthand, that only "works" if you already know what the formula for Capacitive Reactance is.

Speaking of "double standards", earlier in this thread you were happy that your calculator gave you the answer you expected for the original equation.

What exactly would you type into your calculator (or Excel, or ...) to get the correct answer to Xc?

[marie_speeds]

Nah, that's still just nasty shorthand, that only "works" if you already know what the formula for Capacitive Reactance is.

Speaking of "double standards", earlier in this thread you were happy that your calculator gave you the answer you expected for the original equation.

What exactly would you type into your calculator (or Excel, or ...) to get the correct answer to Xc?

Very early in my responses to thread I stated 2 as done in my head, stated that on calculator I also got 2 using 48/(2(9+3)) and got 2 using 48/2(9+3). I also stated in thread that the entire denominator of original was 2(9+3). But was explicity told no no no as I am now implying brackets that aren't there. So exactly what double standard are you referring to? When I have maintained my same position from the start. Others of course have started drawing very cute pictures which show a change in the equation to justify their answers and will now not answer my equation using the exact same method they used to solve thread OP, so I say go ahead answer the question without implied brackets, both equations are written in the same format so it should be easy....

[BoristheBiter]

Very early in my responses to thread I stated 2 as done in my head, stated that on calculator I also got 2 using 48/(2(9+3)) and got 2 using 48/2(9+3). I also stated in thread that the entire denominator of original was 2(9+3). But was explicity told no no no as I am now implying brackets that aren't there. So exactly what double standard are you referring to? When I have maintained my same position from the start. Others of course have started drawing very cute pictures which show a change in the equation to justify their answers and will now not answer my equation using the exact same method they used to solve thread OP, so I say go ahead answer the question without implied brackets, both equations are written in the same format so it should be easy....

I think this is where the use of the / symbol has led to ambiguity in this equation.
But whether it is a fraction or division, 2(9+3) is a complete equation so therefore should be completed first regardless of extra brackets (that aren't needed) otherwise it would be written 48/2*(9+3).

[pzkpfw]

Very early in my responses to thread I stated 2 as done in my head, stated that on calculator I also got 2 using 48/(2(9+3)) and got 2 using 48/2(9+3). I also stated in thread that the entire denominator of original was 2(9+3). But was explicity told no no no as I am now implying brackets that aren't there. So exactly what double standard are you referring to? When I have maintained my same position from the start. Others of course have started drawing very cute pictures which show a change in the equation to justify their answers and will now not answer my equation using the exact same method they used to solve thread OP, so I say go ahead answer the question without implied brackets, both equations are written in the same format so it should be easy....

Just work out the answer to your Reactive Capacitance question, using your calculator. Then tell us how you did it.

[Bald Eagle]

12 pages of thread - best laugh I've had in ages.

[marie_speeds]

Just work out the answer to your Reactive Capacitance question, using your calculator. Then tell us how you did it.

Mods can we get a "sigh" smiley please?

It is capacitive reactance and the answer is 39.79 ohms (2d.p) using wait for........

implied brackets which I have been steadfastly told by you and others does not exist and that my use of it in the the OP equation was incorrect mathematics....
So solving my problem your way without implied brackets 1/2 multiplied by pifC is 6.2832...and that answer sorry to say would be a big fat fail in engineering maths class....

[Jantar]

Its quite simple really, just look at the way it was written.

48/2(9+3) is not the same as 48(9+3)/2

Obviously, in this case, everything after / is the demominator, and so the answer is 2.

[Bald Eagle]

Its quite simple really, just look at the way it was written.

24/2(9+3) is not the same as 24(9+3)/2

Obviously, in this case, everything after / is the demominator, and so the answer is 2.

Are you saying in long hand 24 divided by 2 times (12) is 2

I thought 24 divivded by 24 was 1 .

.... sorry couldn't resist

[pzkpfw]

Mods can we get a "sigh" smiley please?

It is capacitive reactance and the answer is 39.79 ohms (2d.p) using wait for........

implied brackets which I have been steadfastly told by you and others does not exist and that my use of it in the the OP equation was incorrect mathematics....
So solving my problem your way without implied brackets 1/2 multiplied by pifC is 6.2832...and that answer sorry to say would be a big fat fail in engineering maths class....

Right, my main point in that question was just to clarify that yes, you do need to add those "implied" brackets to get the correct answer.

i.e. you need to type it into your calculator as 1 / ( ... ), and you only know you need to do that, by already knowing the correct formula.

The contradiction I referred to was: a. you were happy to type 48/2(9+3) as written into your calculator and get the answer you expected; but if you type your new formula into a calculator as written you'll get an answer you consider wrong. Isn't that a "double standard"?

The formula as presented by you intially is sloppy, and requires use of an assumption that is not supported by standard mathematics. None of your posts in this thread have provided a valid standard mathematical reason to assume those "implied brackets".


(test, see if Latex link will work here:

Xc=1/2piFC

Xc=1/(2piFC)


OK, dunno why the latex link is so awful (e.g. it's not showing the division line), but it shows the right overall format.
)



Part 2: if you were told X = 1/2 + 3, what would you say X is?