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93EXCivic
93EXCivic SuperDork
4/13/11 8:55 a.m.
92CelicaHalfTrac wrote: Standing alone.... 2*(9+3) = 2(9+3), sure... But in the larger context, you're all fabricating brackets to make (48÷2)(9+3). There's no parentheses separating 2 from (9+3) like that in the original equation.

Yes but there is no parentheses around the 2(9+3).

So following order of operations you first do 9+3=12

Then multiplication and division from left to right so 48/2= 24

Then 24*12= 288

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 8:57 a.m.

^ this.....see how that is solved looking like the original equation.......... just saying, not adding this (, [, or { and finding x and so on

24(12)

I'm not going against anyones extra training and knowledge and stuff, I know I know, i'm just a dumb kid that my highest education is high school, but I just know you have to solve it like it's written, there's no need for going into bracket detail. Just the use of pemdas, it's just simple math, and that's how this equation is written and supposed to be solved, exactly how it's written there.

Jay
Jay SuperDork
4/13/11 9:02 a.m.
93EXCivic wrote: Yes but there is no parentheses around the 2(9+3).

Yes there are, it's implicit! By the notation used you treat that exactly as if there are parentheses around it!

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:09 a.m.

yeah but wouldn't there be parenthesis around it if was wanted to be there in the first place?? like "ok, now it's time to switch it up, I want to write it 48/(2(9+3), then yes correct

(48/2(9+3)

DILYSI Dave
DILYSI Dave SuperDork
4/13/11 9:10 a.m.
93EXCivic wrote:
92CelicaHalfTrac wrote: Standing alone.... 2*(9+3) = 2(9+3), sure... But in the larger context, you're all fabricating brackets to make (48÷2)(9+3). There's no parentheses separating 2 from (9+3) like that in the original equation.
Yes but there is no parentheses around the 2(9+3). So following order of operations you first do 9+3=12 Then multiplication and division from left to right so 48/2= 24 Then 24*12= 288

Left to right is a convention. Communicative Property of Multiplication is a law.

Laws beat conventions, therefore the answer is 2.

93EXCivic
93EXCivic SuperDork
4/13/11 9:11 a.m.
Jay wrote:
93EXCivic wrote: Yes but there is no parentheses around the 2(9+3).
Yes there are, it's implicit! By the notation used you treat that exactly as if there are parentheses around it!

No it isn't implicit.

scardeal
scardeal HalfDork
4/13/11 9:12 a.m.
Jay wrote: I'm not wrong! I'm not saying anything about the operation in the brackets or that brackets somehow "apply to what's outside themselves"??? I'm not really sure what you meant by that. If you have an expression, such as 2x or 2(y+b) or 2(e^iθ - 1), or anything like that, there is a so-called implied multiplication where the 2 meets the bracket. This is not the same as just writing an × sign! What it is is a shorthand for doing the whole expression in brackets, so 2(y+b) is actually (2 × (y+b)). Mathematical notation is full of "shorthands" and implicit syntax like that. Stop trying to throw BEDMAS at a term which it's not applicable to! Here's another way of thinking about it if that's not clear. 2(expression) means (double the value of this expression), and not 2 × (expression). A lot of the time they evaluate to the same thing, but not always! This is one of those cases.

It IS functionally the same.

If this were computer code with a function called "2", you'd be right. However, this is simple algebra, and writing
2(9+3)
is EXACTLY the same as writing
2 * (9 + 3)

Apparent ambiguities like this is why there's polish notation (or reverse polish notation). Nobody who wants to be clear would write it that way, anyway.

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:12 a.m.

I agree ^ and yes, IT'S SIMPLE, BASIC, CLEAN CUT MATH

2 AND 288 i'm asking Bill Nye, he's good with science and numbers

mtn
mtn SuperDork
4/13/11 9:17 a.m.

scardeal wrote: Apparent ambiguities like this is why there's polish notation (or reverse polish notation). Nobody who wants to be clear would write it that way, anyway.
mtn wrote: Now, for a little more fun: What is 9 3 + 48 2 ÷ *?
Jay
Jay SuperDork
4/13/11 9:18 a.m.
scardeal wrote: If this were computer code with a function called "2", you'd be right. However, this is simple algebra, and writing 2(9+3) is EXACTLY the same as writing 2 * (9 + 3)

No, it's exactly the same as writing (2 * (9 + 3)). There's a difference!

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:18 a.m.

but see that's the thing it ISN'T written like that, yes you think that in your head but when you add parenthesis like that it totally changes the original equation

ok, everyone get a piece of paper, do it manually, no calculators. Write it in EXACTLY how it's written. Then do the LAW in equations, PEMDAS and get the answer, written out on paper and doing what I took from all these years and classes, doing the SIMPLE equation, nothing fancy at all, I got, well you already know

Jay
Jay SuperDork
4/13/11 9:20 a.m.
93EXCivic wrote: No it isn't implicit.

Look, if you accept that there can be an implicit x sign, than you have to accept there can be implicit brackets around the whole term. You can't have one without the other.

DILYSI Dave
DILYSI Dave SuperDork
4/13/11 9:23 a.m.
NickF40 wrote: but see that's the thing it ISN'T written like that, yes you think that in your head but when you add parenthesis like that it totally changes the original equation ok, everyone get a piece of paper, do it manually, no calculators. Write it in EXACTLY how it's written. Then do the LAW in equations, PEMDAS and get the answer, written out on paper and doing what I took from all these years and classes, doing the SIMPLE equation, nothing fancy at all, I got, well you already know

48÷2(9+3)

P = 48÷2(12)
E = n/a
M = 48÷24
D = 2
A = n/a
S = n/a

Done.

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:26 a.m.

the division comes before the multiplication, when you get them together in the same line like that, you do which ever ones first from the left......PEMDAS can be switched to PEDMSA.................2(12) is the same as 2x12

http://www.mathmojo.com/interestinglessons/order_of_operations/order_of_operations.html

DILYSI Dave
DILYSI Dave SuperDork
4/13/11 9:31 a.m.
NickF40 wrote: the division comes before the multiplication, when you get them together in the same line like that, you do which ever ones first from the left......PEMDAS can be switched to PEDMSA.................2(12) is the same as 2x12 http://www.mathmojo.com/interestinglessons/order_of_operations/order_of_operations.html

Communicative property of multiplication > left to right convention.

92CelicaHalfTrac
92CelicaHalfTrac SuperDork
4/13/11 9:32 a.m.
mtn wrote:
scardeal wrote: Apparent ambiguities like this is why there's polish notation (or reverse polish notation). Nobody who wants to be clear would write it that way, anyway.
mtn wrote: Now, for a little more fun: What is 9 3 + 48 2 ÷ *?

the answer is 575/*

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:33 a.m.

haha

I understand that and I understand 12 is in the parenthesis and your supposed to do them first but it isn't an equation, it's just a whole number, unless we're supposed to do 1*2, which your supposed to treat like the parenthesis aren't there anymore. I mean I fully understand how you guys are getting 2 it's just that from what I learned I though what I knew about PEMDAS is wrong and what our teachers taught us then is wrong what gives?

fast_eddie_72
fast_eddie_72 Dork
4/13/11 9:33 a.m.
Jay wrote: Yes there are, it's implicit! By the notation used you treat that exactly as if there are parentheses around it!

Jay, I'm sure you're not making this up. I tried to find this rule somewhere. I don't know enough about it to make the google machine work. Can you just post a link to something that explains how this works? I think that would end this quickly.

Jay
Jay SuperDork
4/13/11 9:36 a.m.

BEDMAS/PEDMAS was never supposed to mean "division before multiplication", when I was in school it was always taught that they were the same step. So B, E, D&M, A&S if you want. Obviously you have to evaluate the equation logically to determine what goes first. For example we can all agree that you would never evaluate

1   
2x3

as anything other than 1/6 right? (NEVER (1/2)x3!) But that's the exact same situation we have here.

Regardless, BEDMAS only applies to an implicit multiplication as if it were an expression in brackets. BEDMAS is a simplified guide taught to make life easier for public school students and not a hard & fast rule that must be slavishly adhered to. You have to read the whole equation before you can determine where to apply it!

DILYSI Dave
DILYSI Dave SuperDork
4/13/11 9:36 a.m.
NickF40 wrote: haha I understand that and I understand 12 is in the parenthesis and your supposed to do them first but it isn't an equation, it's just a whole number, unless we're supposed to do 1*2, which your supposed to treat like the parenthesis aren't there anymore.

Then do factoring if you don't like treating it like an equation.

48÷2(9+3)

48÷(18+6)

48÷24

2

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:41 a.m.

I'm learning more about math than ever!! Wow, I guess i'm finally seeing this finally.......now my sister explained it to me...wow

NickF40
NickF40 GRM+ Memberand HalfDork
4/13/11 9:42 a.m.

You have to figure out the problem in simplest form I guess, so PEMDAS then takes in affect, you have to solve the other problem first.

It all depends on how it's written because a horizontal division is a total different view then what's written here

The only thing that cancels each other out is negative numbers

GregW
GregW New Reader
4/13/11 9:45 a.m.

I do not understand Greek or Sanskrit.

I did the original as 48/ 2 x(9+3) as 48/(2x12) = 2

fast_eddie_72
fast_eddie_72 Dork
4/13/11 9:46 a.m.
Jay wrote: BEDMAS/PEDMAS was never supposed to mean "division before multiplication", when I was in school it was always taught that they were the same step. So B, E, D&M, A&S if you want. Obviously you have to evaluate the equation logically to determine what goes first. For example we can all agree that you would never evaluate 1    2x3 as anything other than 1/6 right? (NEVER (1/2)x3!) But that's the exact same situation we have here. Regardless, BEDMAS only applies to an implicit multiplication as if it were an expression in brackets. BEDMAS is a simplified guide taught to make life easier for public school students and not a hard & fast rule that must be slavishly adhered to. You have to read the whole equation before you can determine where to apply it!

I said all that on page one. So why don't we get the same answer. And why do you do the multiplication before the division when the division comes first.

T.J.
T.J. SuperDork
4/13/11 9:51 a.m.

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