This topic is locked
Are you saying that 48÷2(9+3) is not equivalent to 48÷2×(9+3)?
Factoring out the 2 is equivalent to multiplication. You're still attempting to do that before the division, i.e. not following the order of operations.
Further research turned up this, if you care to read it.
Math Problem
- #151
- 11 April 2011 - 09:52 PM
wacko, on 11 April 2011 - 09:52 PM, said:
Are you saying that 48÷2(9+3) is not equivalent to 48÷2×(9+3)?
I am saying they are different. Factored terms and elements in an equation, according to your own posted article, would fall under "implied multiplication."
But please read my warning disclaimer. My notation of this is best suited for functional analysis that would come in high level math courses or in the sciences.
What I say as a physicist may not be relative to the testing of arithmetic skills.
- #152
- 11 April 2011 - 11:44 PM
Kaxbe, on 11 April 2011 - 06:29 AM, said:
Fuck this shit, I'm an arts major. Obviously, I have no idea what I'm talking about. Fuck you.
Blazer, on 11 April 2011 - 01:41 PM, said:
The basic mathematical rules are these:
1. Calculations must be done from left to right.
1. Calculations must be done from left to right.
Blazer, on 11 April 2011 - 02:42 PM, said:
...I barely pass Math at school 
There is no set standard when it comes to this because this is only an issue when you have to write the expression in only one line (i.e. when using calculators or writting on the computer). When giving someone the problem hand-written (or written using a better program which allows fractions), the ambiguity disapears as you can see whether 48 is over (divided by) all the rest of the expression or just by 2.
I would think that when using these badly written expressions, calculators WOULD go from left to right, but as kaxbe showed us, this is not always the case.
The best argument someone has given me yet is this one:
Quote
The answer is 288 because that is what excel says and EXCEL IS GOD!!!!
- #153
- 11 April 2011 - 11:59 PM
- Kaxbe
- Member
Migrant, on 11 April 2011 - 11:59 PM, said:
Kaxbe, on 11 April 2011 - 06:29 AM, said:
Fuck this shit, I'm an arts major. Obviously, I have no idea what I'm talking about. Fuck you.
Oh, fuck you. But hey! You're the expert here! I guess I'll go do art major-esque things and don my shutter shades and worn-down plaid shirt while drinking some Pabst Blue Ribbon and listening to this all-synthesizer band that I saw down at the coffee shop a few weeks ago before going to my friend's art exhibition in the back stockroom of the Urban Outfitters where she works.
In all seriousness, though, I was going by how I was taught in the past and trying to keep in the perspective of how the original problem was presented, in a grade school level maths book which I found whilst perusing the multiple forums I am on.
- #154
- 12 April 2011 - 12:35 AM
So basically... you are going by which posts you found most convincing in other forums. Good one.
- #155
- 12 April 2011 - 12:43 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned 
wacko, on 11 April 2011 - 09:52 PM, said:
Are you saying that 48÷2(9+3) is not equivalent to 48÷2×(9+3)?
Wait, why are those different?
In either case, shouldn't you devide first by the system you are arguing?
Vanvoltra, on 11 April 2011 - 09:21 PM, said:
As I mentioned on pg 2, this problem is the confusion of terms with the lack of brackets.
Unfortunately, this being a low level arithmetic problem, the writers did not flush it out as much as they could have.
I blame writing!
It is very important for us to know where terms are within an equation so there is always an abundance of brackets.
Unfortunately, this being a low level arithmetic problem, the writers did not flush it out as much as they could have.
I blame writing!
It is very important for us to know where terms are within an equation so there is always an abundance of brackets.
Look at that, someone is talking about the need for brackets. Brackets are only needed because such a problem exists in the first place. Why is the grammer so broken that we have to jerry rig all this together every time?
JHawkNH, on 11 April 2011 - 07:58 PM, said:
Blazer, on 11 April 2011 - 07:18 PM, said:
As I recall we were thought that multiplying has priority over dividing, so ...
Then you were taught wrong. Neither multiplying or dividing has priority over the other. That is why they must be worked from left to right.
Look, "taught wrong". At the point where we have admited that some of us have been taught wrong, how can we know if it is us or the other person? We can't.
- #157
- 12 April 2011 - 12:45 AM
- Blazer
- Member
Craft aids, on 12 April 2011 - 12:45 AM, said:
JHawkNH, on 11 April 2011 - 07:58 PM, said:
Blazer, on 11 April 2011 - 07:18 PM, said:
As I recall we were thought that multiplying has priority over dividing, so ...
Then you were taught wrong. Neither multiplying or dividing has priority over the other. That is why they must be worked from left to right.
Look, "taught wrong". At the point where we have admited that some of us have been taught wrong, how can we know if it is us or the other person? We can't.
I do not recall admitting anything until now, but yes. Seems our teacher wasn't really good, and taught us wrongly so I apologize for that on my behalf, seems I was wrong in my assumption.
Spoiler
This post has been edited by Blazer: 12 April 2011 - 01:08 AM
- #158
- 12 April 2011 - 01:08 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
What did I just say?
If someone could be be "taught wrong" so could everyone else.
If someone could be be "taught wrong" so could everyone else.
This post has been edited by Craft aids: 12 April 2011 - 01:14 AM
- #159
- 12 April 2011 - 01:14 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
I am admiting that both answers are equle and have been doing so for pages.
- #161
- 12 April 2011 - 01:28 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
What? no picture Wolf?
- #163
- 12 April 2011 - 01:36 AM
- Wolf
- Member
ya, you want a picture?
I can't you some image extension, so I'll just give the url and if anyone wants to waste their time and correct it then be my guest
http://t3.gstatic.co...cS50g0tQt2A&t=1
I can't you some image extension, so I'll just give the url and if anyone wants to waste their time and correct it then be my guest
http://t3.gstatic.co...cS50g0tQt2A&t=1
This post has been edited by Wolf: 12 April 2011 - 01:42 AM
- #164
- 12 April 2011 - 01:37 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Oh, I meant spam.
It's good to see we are on the same page mathmaticaly at least.
It's good to see we are on the same page mathmaticaly at least.
- #165
- 12 April 2011 - 01:49 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Well, you would have to be using math from two different teachers and two different years to have been taught both ways. At least I hope you would.
- #167
- 12 April 2011 - 01:59 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Or someone could just figure out which danm method we are going to teach the world.
- #170
- 12 April 2011 - 02:10 AM
Or we could use brackets and remove ALL ambiguity.
- #171
- 12 April 2011 - 02:15 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
We would, but people just wouldn't do it and you know it. It is most assuredly a good option, but the original problem in the base of the syntax for the language is not solved.
I like the opstion; switch to that polish thing(unless it has more issues) and just freaking choose one of the systems and teach it universaly.
I like the opstion; switch to that polish thing(unless it has more issues) and just freaking choose one of the systems and teach it universaly.
This post has been edited by Craft aids: 12 April 2011 - 02:24 AM
- #172
- 12 April 2011 - 02:24 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
It is one of the two ways this is taught.
The other way treats M and D as the same thing and A and S as the same thing.
PEMDAS is the method that blazer was using.
The other way treats M and D as the same thing and A and S as the same thing.
PEMDAS is the method that blazer was using.
- #174
- 12 April 2011 - 02:36 AM
- matty_batty0
- Member
You would think that at some point in time some official person would have gone to the effort to just lay down the rules and give a universal way to solve this. I mean if they go to all the effort to prove something as simple as 1+1=2 then why would they have not felt the need to prove something like this? Which could actually cause a mathematical error if a standard is not in place.
This post has been edited by matty_batty0: 12 April 2011 - 04:19 AM
- #175
- 12 April 2011 - 04:18 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Dear lord.
it has never been so frustraiting to hear someone finaly agreeing with you.
it has never been so frustraiting to hear someone finaly agreeing with you.
- #176
- 12 April 2011 - 04:20 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
WTF, on 12 April 2011 - 04:21 AM, said:
What are we in elementary school
48/2(9+3)
48/2x12
24x12
288
Solve 1+827373738x83826162x83726748382x982827 x7278484847x847262829x0=
48/2(9+3)
48/2x12
24x12
288
Solve 1+827373738x83826162x83726748382x982827 x7278484847x847262829x0=
First, I would place "()" to get right on past the broken grammer
1 + (827373738*x*83826162*x*83726748382*x*982827*x*7278484847*x*847262829*x*0)
Then, I would place the "+1" at the end and seporate the factor x
(6x*827373738*83826162*83726748382*982827*7278484847*847262829*0) +1
Then, you put a zero in it so I would jsut let it nom the whole thing.
1
Happy?
- #180
- 12 April 2011 - 04:26 AM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
*Hit's Valumior in the head with 1 internets*
Happy?
Now shoo referance maker.
Happy?
Now shoo referance maker.
- #182
- 12 April 2011 - 07:06 AM
- Valumior
- Member
Ok, now jokes aside. The answer is 288. Why?
48/2*(9+3)=48/2*12
Now this is the moment which causes so much confusion but consider:
x/2=x*0.5
thus
48/2*12=48*0.5*12=48*6=288
Similar to:
1-2+3=1+(-2)+3=2
Sorry for not using math terms but I'm too lazy to check the dictionary for that.
Edit:
Holy crap what a mess 48÷2(9+3) = ? | Know Your Meme
So the whole problem is in those acronyms... Good we don't have such confusing crap here... Standard order of operations damn it!
48/2*(9+3)=48/2*12
Now this is the moment which causes so much confusion but consider:
x/2=x*0.5
thus
48/2*12=48*0.5*12=48*6=288
Similar to:
1-2+3=1+(-2)+3=2
Sorry for not using math terms but I'm too lazy to check the dictionary for that.
Edit:
Holy crap what a mess 48÷2(9+3) = ? | Know Your Meme
So the whole problem is in those acronyms... Good we don't have such confusing crap here... Standard order of operations damn it!
This post has been edited by Valumior: 12 April 2011 - 11:32 AM
- #183
- 12 April 2011 - 11:07 AM
- matty_batty0
- Member
Seems a bit odd for that link to say that this is used for trolling sometimes... but then again, people seem to be getting pretty frustrated here 
- #185
- 12 April 2011 - 01:39 PM
- JHawkNH
- Member
Blazer, on 12 April 2011 - 01:28 AM, said:
I do not really see anyone in here admitting that he or she was wrong besides me, since I've seen the error I did during explaining and trying to prove my point in argument.
I hope you understand that I am not trying to demean you in any way. I understand better then most people how important a proper understanding of mathamatics is to getting ahead in the world. I just wanted you to see the proper way to use the rules on this equation so that in the future you can solve problems like it without any issues.
- #186
- 12 April 2011 - 03:28 PM
matty_batty0, on 11 April 2011 - 04:30 PM, said:
There is not the slightest part in any area of any maths which would say 20 does not equal (20), they are the exact same thing in every way.
20 = (20) because 20 = 20*1
Just because there is nothing near the bracket to multiply or divide does not mean that there is nothing at all because nothing = 0.
- #187
- 12 April 2011 - 03:37 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Valumior, on 12 April 2011 - 11:07 AM, said:
Ok, now jokes aside. The answer is 288. Why?
48/2*(9+3)=48/2*12
Now this is the moment which causes so much confusion but consider:
x/2=x*0.5
thus
48/2*12=48*0.5*12=48*6=288
Similar to:
1-2+3=1+(-2)+3=2
Sorry for not using math terms but I'm too lazy to check the dictionary for that.
Edit:
Holy crap what a mess 48÷2(9+3) = ? | Know Your Meme
So the whole problem is in those acronyms... Good we don't have such confusing crap here...
Standard order of operations damn it!
48/2*(9+3)=48/2*12
Now this is the moment which causes so much confusion but consider:
x/2=x*0.5
thus
48/2*12=48*0.5*12=48*6=288
Similar to:
1-2+3=1+(-2)+3=2
Sorry for not using math terms but I'm too lazy to check the dictionary for that.
Edit:
Holy crap what a mess 48÷2(9+3) = ? | Know Your Meme
So the whole problem is in those acronyms... Good we don't have such confusing crap here...
Standard order of operations damn it!
If only there WAS a standard order of operations. Insted, we have two.
Also, here is the other proof in your method.
48/2*12
48/24
48*0.0416666667
2
- #188
- 12 April 2011 - 04:30 PM
- esalaka
- Banned
Craft aids, on 12 April 2011 - 04:30 PM, said:
If only there WAS a standard order of operations. Insted, we have two.
There is a standard order of operatioooons?
Quote
Similarly, care must be exercised when using the slash ('/') symbol. The string of characters "1/2x" is interpreted by the above conventions as (1/2)x. The contrary interpretation should be written explicitly as 1/(2x). Again, the use of brackets will clarify the meaning and should be used if there is any chance of misinterpretation.
This post has been edited by esalaka: 12 April 2011 - 04:44 PM
- #189
- 12 April 2011 - 04:42 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
No, there are two.
So they are not fully standard.
Why the repeating?
WHHY?!?!
So they are not fully standard.
Why the repeating?
WHHY?!?!
- #190
- 12 April 2011 - 04:43 PM
- esalaka
- Banned
Strictly following the standard order there is only one way of solving this, which is (48/2)(9+3).
As explained, for example, on that Wikipedia page I quoted, and on KnowYourMeme linked above (YEAH I KNOW THEY'RE NOT THE MOST TRUSTWORTHY SOURCES MKAY) and I'm trying to look for something in my math books.
Put another way, you either follow the standard rules or don't. Saying they're not 'fully standard' is like saying C99 isn't fully standard because GCC doesn't comply to it perfectly.
As explained, for example, on that Wikipedia page I quoted, and on KnowYourMeme linked above (YEAH I KNOW THEY'RE NOT THE MOST TRUSTWORTHY SOURCES MKAY) and I'm trying to look for something in my math books.
Put another way, you either follow the standard rules or don't. Saying they're not 'fully standard' is like saying C99 isn't fully standard because GCC doesn't comply to it perfectly.
- #191
- 12 April 2011 - 04:55 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Maybe you would have an argument but some math books tell it one way and some tell it anouther. Some calculators compute it one way and some compute it anouther. You could totaly find a different ancwer in the book you are looking at then someone else who is also looking at an equle level book. If that is not a lack of proper standard, what is?
- #192
- 12 April 2011 - 04:59 PM
- matty_batty0
- Member
Really though, maths can not have 2 different answers depending on how you look at the question, so one of the theories must be wrong and one must be right. Not too sure I really care which one it is anymore though.
This post has been edited by matty_batty0: 12 April 2011 - 05:05 PM
- #193
- 12 April 2011 - 05:04 PM
There aren't "theories" here. There are conventions.
In spherical coordinates, north american math books use the greek symbol phi for the azimuth angle, and theta for the polar angle.
In England, they use the opposite. Theta is used for the azimuth angle, and phi for the polar angle.
This means that our expressions for the laplace operator, curl, divergence, and everything else are completely and utterly different. I had this problem last term, my physics book used one thing and my math book the other.
It's not that one is wrong and the other is right - they're BOTH valid calculations provided that they come with an appropriate DEFINITION. As long as I say "and in the paper, I'm using phi for the azimuth", there can be no confusion, and my calculation is fine.
Someone from England won't look at my laplace operator and think "Is this guy on crack? Everyone knows it looks like THIS!", he or she will think "That's odd, what does he mean when he writes theta and phi?". Once they read my definition, everything will be clear.
In spherical coordinates, north american math books use the greek symbol phi for the azimuth angle, and theta for the polar angle.
In England, they use the opposite. Theta is used for the azimuth angle, and phi for the polar angle.
This means that our expressions for the laplace operator, curl, divergence, and everything else are completely and utterly different. I had this problem last term, my physics book used one thing and my math book the other.
It's not that one is wrong and the other is right - they're BOTH valid calculations provided that they come with an appropriate DEFINITION. As long as I say "and in the paper, I'm using phi for the azimuth", there can be no confusion, and my calculation is fine.
Someone from England won't look at my laplace operator and think "Is this guy on crack? Everyone knows it looks like THIS!", he or she will think "That's odd, what does he mean when he writes theta and phi?". Once they read my definition, everything will be clear.
- #194
- 12 April 2011 - 05:09 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Only one of the methods can work at a time. It depends on which system the person who made the proplem had in mind. I definitly don't care which one, it just annoys me extreamly that there is such an error in comuniation presant and no one seems to be able to do anything about it.
- #195
- 12 April 2011 - 05:10 PM
There aren't "theories" here. There are conventions.
In spherical coordinates, north american math books use the greek symbol phi for the azimuth angle, and theta for the polar angle.
In England, they use the opposite. Theta is used for the azimuth angle, and phi for the polar angle.
This means that our expressions for the laplace operator, curl, divergence, and everything else are completely and utterly different. I had this problem last term, my physics book used one thing and my math book the other.
It's not that one is wrong and the other is right - they're BOTH valid calculations provided that they come with an appropriate DEFINITION. As long as I say "and in the paper, I'm using phi for the azimuth", there can be no confusion, and my calculation is fine.
Someone from England won't look at my laplace operator and think "Is this guy on crack? Everyone knows it looks like THIS!", he or she will think "That's odd, what does he mean when he writes theta and phi?". Once they read my definition, everything will be clear.
This isn't science. Math starts with definitions and proves logical consequences. I can't run an experiment on this statement... it's truth or falsehood depends on the definitions you start with and nothing else. It's not like I'm trying to figure out the charge on an electron, which can be either right or wrong.
In spherical coordinates, north american math books use the greek symbol phi for the azimuth angle, and theta for the polar angle.
In England, they use the opposite. Theta is used for the azimuth angle, and phi for the polar angle.
This means that our expressions for the laplace operator, curl, divergence, and everything else are completely and utterly different. I had this problem last term, my physics book used one thing and my math book the other.
It's not that one is wrong and the other is right - they're BOTH valid calculations provided that they come with an appropriate DEFINITION. As long as I say "and in the paper, I'm using phi for the azimuth", there can be no confusion, and my calculation is fine.
Someone from England won't look at my laplace operator and think "Is this guy on crack? Everyone knows it looks like THIS!", he or she will think "That's odd, what does he mean when he writes theta and phi?". Once they read my definition, everything will be clear.
This isn't science. Math starts with definitions and proves logical consequences. I can't run an experiment on this statement... it's truth or falsehood depends on the definitions you start with and nothing else. It's not like I'm trying to figure out the charge on an electron, which can be either right or wrong.
- #196
- 12 April 2011 - 05:11 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Quote
It's not that one is wrong and the other is right - they're BOTH valid calculations provided that they come with an appropriate DEFINITION. As long as I say "and in the paper, I'm using phi for the azimuth", there can be no confusion, and my calculation is fine.
This is what I mean.
If he made it using one system, the same system must be used to read and work with it to get the right answer.
but one school system should have only one method because stuff like this happens otherwise.
- #197
- 12 April 2011 - 05:13 PM
School systems should just teach everyone to use brackets or write fractions so we never have these problems.
- #198
- 12 April 2011 - 05:14 PM
- Craft aids
- That doesn't sound like a rape. That sounds like suprise sex
Banned
Craft aids, on 11 April 2011 - 06:40 AM, said:
Craft aids, on 10 April 2011 - 04:49 AM, said:
48÷2(9+3)
Without a doubt, the parenthesis make the first move clear.
48÷2*12
At this point, one must choose between the order of operations that goes based on symbols only,( () then * then ÷ then + then - ) and the system that goes based on groupings with a secondary system of right to left( () then * and ÷ then + and -). In the first system we always multiply before we divide and in the second system we chose the right most of multipliers and dividers.
48÷24 or 24*12
2 or 288
Without a doubt, the parenthesis make the first move clear.
48÷2*12
At this point, one must choose between the order of operations that goes based on symbols only,( () then * then ÷ then + then - ) and the system that goes based on groupings with a secondary system of right to left( () then * and ÷ then + and -). In the first system we always multiply before we divide and in the second system we chose the right most of multipliers and dividers.
48÷24 or 24*12
2 or 288
See, I got the same answer.
The point of contention is not how to reach the answer but which answer to reach.
And that is based on one spesific moment in the problem.
here
48÷2*12
Right here.
I have no way of proving which one of the syntaxes is correct and you have no way to show me because after we reach the answer, 2 and 288 have no extra sygnificance that would invalidate either one and neither problem had anything to invalidat either of them.
It's taking someones word for it all the way around.
Craft aids, on 11 April 2011 - 04:38 PM, said:
explanation one
48 ÷ x (9 + 3) = 2
48 ÷ 9x + 3x = 2
48 / 12x = 2
4 / x = 2
4 = 2 x
4 / 2 = x
2 = x
explanation two.
48 ÷ x (9 + 3) = 288
((48*9)+(48*3)) ÷ x = 288
(576) = 288x
2 = x
This is not an issue off which version of math works correctly. If you hold yourself to the conventions of the math you use and if the problem was built under the same conventions, you will get a legitamate answer.
This is not an issue of correct and incorect answers.
This is purely and issue of comunication which is the field of the broken grammer that was exploited here.
Blazer, brackets only give priority to the contense.
48 ÷ x (9 + 3) = 2
48 ÷ 9x + 3x = 2
48 / 12x = 2
4 / x = 2
4 = 2 x
4 / 2 = x
2 = x
explanation two.
48 ÷ x (9 + 3) = 288
((48*9)+(48*3)) ÷ x = 288
(576) = 288x
2 = x
This is not an issue off which version of math works correctly. If you hold yourself to the conventions of the math you use and if the problem was built under the same conventions, you will get a legitamate answer.
This is not an issue of correct and incorect answers.
This is purely and issue of comunication which is the field of the broken grammer that was exploited here.
Blazer, brackets only give priority to the contense.
Starwatcher, on 12 April 2011 - 05:11 PM, said:
This isn't science. Math starts with definitions and proves logical consequences. I can't run an experiment on this statement... it's truth or falsehood depends on the definitions you start with and nothing else. It's not like I'm trying to figure out the charge on an electron, which can be either right or wrong.
Oh god, finaly someone agrees!
I dislike that that is all I seem to care about right now but someone agrees! I'm not alone on this!
Starwatcher, on 12 April 2011 - 05:14 PM, said:
School systems should just teach everyone to use brackets or write fractions so we never have these problems.
Agreed, but people will never be so careful.
- #199
- 12 April 2011 - 05:17 PM