|
On April 08 2011 07:01 Retgery wrote:
I see the mistake now, some people see it as (48 )/2 (9+3) and if 48÷2 is seen as a fraction then the answer comes out to 288, but what some (me included) saw was 48÷[2(9+3)] comes out to 2. This question is a bitch...
Yep, it's the assumption that the division sign automatically sets everything to the right in a bracket. Writing it out on a board or paper would help.
The division sign does exactly what it's supposed to. Divide the left number by the right number.
|
Do what's in the parentheses first.Then, it's just left to right.
|
Here's more proof for those of you 2'ers out there.
|
On April 08 2011 06:54 Raysalis wrote:
Although this also means that professors and grad student are lazy and sometimes do not write their equations in the most correct from ^^. Kind of a case of experience breed complacency :p
Actually, speaking as one of that group of people, laziness is not quite what is going on. There are actually two different usages, see my post on page 8.
The two usages are roughly (1) expression to be evaluated, and (2) result of a calculation. The first usage is the mindset you use if you are learning arithmetic (hence all the calls of bedmas by the masses) or when you are interfacing with / writing a computer program. The second is what you use if you are reading mathematics (EDIT: or writing mathematics to be understood by a person, rather than a computer).
|
United States24701 Posts
On April 08 2011 07:02 TurpinOS wrote:
I understand how people are saying that this is misleading, but all in all, 1/2x = (1/2)*x
Yes the simplification of 1/2x = 1/(2x) is very often used in classes but it doesnt change the fact that its not entirely correct.
The answer is 288, the fact that its often used differently in classes doesnt change the answer.
That's the difference between math and other topics... in English if you do something differently enough times it actually BECOMES the correct answer!
I really really hate math statements that are ambiguous due to common usages.
|
I guess if you live in a perfect world where everyone writes exactly what they meant then the answer is always 288.
That is not the real world though, I come across ambiguous notation all the time and have to work out the writers intent/check it/ask about it. It is the role of the author to try and make sure their work is straight forward as possible to eliminate ambiguities.
Another example is some recent reading I was doing, trying to understand my PhD supervisors paper he submitted in 1973 as part of a conference proceedings. With a D dimensional space he used a notation D/2 to indicate D + another 2 fermionic dimensions, then later again used D/2 to indicate D divided by two dimensions. This caused me a great deal of confusion till I went and asked him about it. Today however there are tools available so that this wouldn't happen (i.e can write D/2 for division as \frac{D}{2}).
*edit*
I guess as people are saying the use of a division symbol indicates it is likely to be appearing in a highschool/lower environment and so the question becomes a test of order of operations and would be 288.
|
On April 08 2011 07:00 JinDesu wrote:Show nested quote +On April 08 2011 06:59 exeexe wrote:
i did this:
48÷2(9+3)=
24(9+3) =
216 + 72 =
well that cant be 2 so i picked the other result.
Is that wrong? That's fine, although using the distributive law is a little overkill. That is how this question was meant to be interpreted.
What? If you're using the distributive law then you distribute the 2 to the contents of the bracket before you divide the 48 with the 2(x). Doing it the way exeexe did isn't fine AT ALL.
|
On April 08 2011 07:03 munchmunch wrote:Show nested quote +On April 08 2011 06:54 Raysalis wrote:
Although this also means that professors and grad student are lazy and sometimes do not write their equations in the most correct from ^^. Kind of a case of experience breed complacency :p Actually, speaking as one of that group of people, laziness is not quite what is going on. There are actually two different usages, see my post on page 8. The two usages are roughly (1) expression to be evaluated, and (2) result of a calculation. The first usage is the mindset you use if you are learning arithmetic (hence all the calls of bedmas by the masses) or when you are interfacing with / writing a computer program. The second is what you use if you are reading mathematics.
The issue is that people are automatically replacing ÷ with / and then assuming everything to the right is bracketed.
Computer programs do not have the ÷ symbol generally (well, I only used matlab, so I dunno if other math tools have ÷), and use / instead.
|
it is soooooo 2. I will fight somebody over it.
|
On April 08 2011 07:02 jdseemoreglass wrote:
The problem here is obviously that people are using PEMDAS instead of the superior PEDMAS. Also, several other poor souls are confused enough to be using BEMDAS or BEDMAS, while failing to realize in fact that there are no brackets in mathematics.
Please Excuse Dear My Aunt Sally, people! DUH!
No. I'm pretty sure most people guessing 2 are assuming 1/2x=1/(2x)
It is technically wrong but used all the time in lectures/classes
|
United States24701 Posts
On April 08 2011 07:05 koreasilver wrote:Show nested quote +On April 08 2011 07:00 JinDesu wrote:On April 08 2011 06:59 exeexe wrote:
i did this:
48÷2(9+3)=
24(9+3) =
216 + 72 =
well that cant be 2 so i picked the other result.
Is that wrong? That's fine, although using the distributive law is a little overkill. That is how this question was meant to be interpreted. What? If you're using the distributive law then you distribute the 2 to the contents of the bracket before you divide the 48 with the 2(x). Doing it the way exeexe did isn't fine AT ALL.
I don't think distribution means you have to do it before doing 48/2 thus exeexe's work should be okay albeit silly.
|
On April 08 2011 07:05 JinDesu wrote:Show nested quote +On April 08 2011 07:03 munchmunch wrote:On April 08 2011 06:54 Raysalis wrote:
Although this also means that professors and grad student are lazy and sometimes do not write their equations in the most correct from ^^. Kind of a case of experience breed complacency :p Actually, speaking as one of that group of people, laziness is not quite what is going on. There are actually two different usages, see my post on page 8. The two usages are roughly (1) expression to be evaluated, and (2) result of a calculation. The first usage is the mindset you use if you are learning arithmetic (hence all the calls of bedmas by the masses) or when you are interfacing with / writing a computer program. The second is what you use if you are reading mathematics. The issue is that people are automatically replacing ÷ with / and then assuming everything to the right is bracketed. Computer programs do not have the ÷ symbol generally (well, I only used matlab, so I dunno if other math tools have ÷), and use / instead.
where is ÷ on a keyboard anyway ? I dont have it.....
|
On April 08 2011 07:05 Cush wrote:
it is soooooo 2. I will fight somebody over it.
LMAO I've never seen a fight over math, that would be interesting.
|
well i dont care my mind is set to see it has 40/(2(9+3)) dunno why but thats how i see it i can see im wrong
|
United States24701 Posts
I am not aware of any difference between / and the other division sign... they both mean the same thing to me. Can anyone point me to a reference that says otherwise?
|
This is a very simple PEMDAS(Parenthesis, Exponents, Multiply, Divide, Addition, Subtraction) problem, such as 2+2÷2 = 1,
Parenthesis first, so 48÷2(9+3)=48÷2(12)
Next is Exponents, but we don't have any, so we go to multiply.
2(12) is multiplication, so that comes next.
So we multiply: 48÷2(12)=48÷24
Division after that 48÷24 = 2
We have nothing to add
We have nothing to subtract
Problem solved.
|
United States24701 Posts
On April 08 2011 07:08 cYberc0re wrote:
This is a very simple PEMDAS(Parenthesis, Exponents, Multiply, Divide, Addition, Subtraction) problem, such as 2+2÷2 = 1,
Parenthesis first, so 48÷2(9+3)=48÷2(12)
Next is Exponents, but we don't have any, so we go to multiply.
2(12) is multiplication, so that comes next.
So we multiply: 48÷2(12)=48÷24
Division after that 48÷24 = 2
We have nothing to add
We have nothing to subtract
Problem solved.
PEMDAS does not mean do multiplication before division. It means do EITHER multiplication OR division, whichever comes first.
|
On April 08 2011 07:06 Coolbeans wrote:Show nested quote +On April 08 2011 07:02 jdseemoreglass wrote:
The problem here is obviously that people are using PEMDAS instead of the superior PEDMAS. Also, several other poor souls are confused enough to be using BEMDAS or BEDMAS, while failing to realize in fact that there are no brackets in mathematics.
Please Excuse Dear My Aunt Sally, people! DUH! No. I'm pretty sure most people guessing 2 are assuming 1/2x=1/(2x) It is technically wrong but used all the time in lectures/classes
It is not technically wrong at all, see my post above.
And yes, I'm just replying to all of these because I'm on a massive procrastination binge.
|
On April 08 2011 07:08 cYberc0re wrote:
This is a very simple PEMDAS(Parenthesis, Exponents, Multiply, Divide, Addition, Subtraction) problem, such as 2+2÷2 = 1,
Parenthesis first, so 48÷2(9+3)=48÷2(12)
Next is Exponents, but we don't have any, so we go to multiply.
2(12) is multiplication, so that comes next.
So we multiply: 48÷2(12)=48÷24
Division after that 48÷24 = 2
We have nothing to add
We have nothing to subtract
Problem solved.
On April 08 2011 07:02 jdseemoreglass wrote:
The problem here is obviously that people are using PEMDAS instead of the superior PEDMAS. Also, several other poor souls are confused enough to be using BEMDAS or BEDMAS, while failing to realize in fact that there are no brackets in mathematics.
Please Excuse Dear My Aunt Sally, people! DUH!
|
On April 08 2011 07:05 koreasilver wrote:Show nested quote +On April 08 2011 07:00 JinDesu wrote:On April 08 2011 06:59 exeexe wrote:
i did this:
48÷2(9+3)=
24(9+3) =
216 + 72 =
well that cant be 2 so i picked the other result.
Is that wrong? That's fine, although using the distributive law is a little overkill. That is how this question was meant to be interpreted. What? If you're using the distributive law then you distribute the 2 to the contents of the bracket before you divide the 48 with the 2(x). Doing it the way exeexe did isn't fine AT ALL.
a*b (c+d) = a*b*c + a*b*d
The distributive law is maintained as long as all the factors are correctly distributed. It doesn't matter when or where you do it, as long as the factors are correctly distributed.
48÷2 (9+3)
48÷2x9 + 48÷2x 3
If there's anything that CANNOT be distributed in the equation, then that's where you have to be careful.
|
|
|
|
|
|
EPT
