Half of you will get this wrong: 48÷2(9+3) = 288 or 2?

[hoyle21]

no no no. God people. You can't do that. If it were upper level math, you'd start seeing your errors.

It's PEMDAS
Therefore.

(9+3) = 12
2(12)= 24


48
-- = 2
24

Why do you work right to left? The point to this problem is to show how important communication is. Both answers are correct, but I would lean towards 288 just because it is done left to right. There is no rule that says go left to right though. In fact it is not supposed to matter if multiplication or division is done first, because division is just the multiplication of an inverse.

 

[dteller1]

actually.... there is a rule that you work from left to right check the links i posted

hell even check this PEDMAS one

Order of Operations - PEMDAS (with worked solutions & videos)

it clearly states you work from left to right

i will quote
"Then, carry out multiplication or division, working from left to right"
straight from the page

 

[hoyle21]

actually.... there is a rule that you work from left to right check the links i posted

hell even check this PEDMAS one

Order of Operations - PEMDAS (with worked solutions & videos)

it clearly states you work from left to right

i will quote
"Then, carry out multiplication or division, working from left to right"
straight from the page

You are right it does say that. Either way it is a poorly written problem. Subtraction is nothing more than adding a negative, and division is multiplication of an inverse. It really "shouldn't" matter.

I still believe the point to the problem is to show how important communication is, not to really get an answer.

 

[ZECH]

OH yea, because TODAY'S leaders are any better

You got a good point!

 

[bulldogz]

PEDMAS is the same ...Parenthesis Exponents Division Multiplication Addition Subtraction just different acronym

BUT if you actually follow it you'll see you are wrong

48÷2(9+3) becomes 48÷2x(9+3)


becomes 48÷2x(12) division and multiplication are equal priority so you read from left to right when signs are equal so...

it becomes 48÷2 first = 24

and finally x 12 = 288.

PEMDAS is not the same as BIDMAS....parenthesis and brackets are totally different when it comes to mathematics...

Your equation is incorrect...x12 = 288..?????....you still have to solve for "x" in your equation/explanation...plus you just can’t put "x" where ever you want...”x” has to replace a number within the equation…check out post #57....

http://www.ironmagazineforums.com/2250713-post57.html

 

[maniclion]

You are right it does say that. Either way it is a poorly written problem. Subtraction is nothing more than adding a negative, and division is multiplication of an inverse. It really "shouldn't" matter.

I still believe the point to the problem is to show how important communication is, not to really get an answer.

It's a poorly written equation, but there still is a right answer...

 

[dteller1]

X is a multiplication sign............i didnt think anyone wouldnt understand that....wow

 

[troubador]

If this were a real equation it would be written differently. By real equation I mean like the Bernoulli equation or ideal gas law.

 

[hoyle21]

http://www.physicsforums.com/showthread.php?t=488334

Even the physics guys are struggling with it.

 

[maniclion]

In other news today, people across the internet have actually been debating on something intellectually stimulating.....that's right MATH and to top it off it seems to have been started at a bodybuilding website....

 

[maniclion]

Wikipedia page on Order of Operations has changed (probably cause of this?), they had links to some Laws of logic and they disappeared, I was going to read them to find a Proof but now I can't find them....

The person who proves this will be kind of famous maybe?

 

[danzik17]

In other news today, people across the internet have actually been debating on something intellectually stimulating.....that's right MATH and to top it off it seems to have been started at a bodybuilding website....

Unfortunately said math is of the 5th grade level, but hey it's a start.

 

[maniclion]

Why is math coming into my life so much lately? The other night I watched this movie called Fermat's Room and the plot was tied to Goldbach's Conjecture, so I looked it up and got caught up in it, then I watched a show on Discovery about blackholes and looked up the math related to them and now this....it's a conspiracy to drive me more insane I think...

YouTube Video

 

[maniclion]

Unfortunately said math is of the 5th grade level, but hey it's a start.

I recall Pre-Algebra in 8th grade, but in 5th? Maybe in India or China...

 

[danzik17]

I recall Pre-Algebra in 8th grade, but in 5th? Maybe in India or China...

It's just basic order of operations. When did you go to school? I remember doing algebra maybe around 7th grade in middle school, though I did skip a couple of the easier classes.

 

[maniclion]

It's just basic order of operations. When did you go to school? I remember doing algebra maybe around 7th grade in middle school, though I did skip a couple of the easier classes.

Texas public schools Honors classes...

 

[maxpro2]

Google's calculator says 288.

48÷2(9+3) - Google Search

 

[hoyle21]

Google's calculator says 288.

48÷2(9+3) - Google Search

and google is never wrong.

 

[Built]

Both answers are correct,

No, they're not. That's the beauty of mathematics. Right or wrong isn't a matter of opinion; it's a matter of logic.

You've heard from at least two former math tutors already - me, and ihateschool.

My first degree was in Mathematics. I broke it down for you earlier in this thread.

Would this make it easier?
______________________________________

I'll get rid of the (9+3) by simplifying it down to 12.

Like subtraction, division must not be performed in just any order - barring parentheses, it must be performed from left to right.

However, multiplication may be performed in any order.

As correctly noted by others, division by 2 is simply multiplication by its reciprocal, ½:

Thus

48 ÷ 2 ?? 12​

becomes

48 ?? ½ ?? 12​

Which may be evaluated in whatever order you like. For example, this one:

48 ?? 12 ?? ½​

48 ?? 12 = 576, and 576 ?? ½ = 288​

Or this one, if you prefer:

½ ?? 12 ?? 48​

½ ?? 12 = 6, and 6 ?? 48 = 288​

 

[danzik17]

Texas public schools Honors classes...

/shrug

I don't know then. I think it's more the timeframe than where one went. The math being taught in high school these days is pathetic, playing to the lowest common denominator. Thanks "No Child Left Behind" a.k.a "No Child Leaps Forward".

 

[hoyle21]

No, they're not. That's the beauty of mathematics. Right or wrong isn't a matter of opinion; it's a matter of logic.

You've heard from at least two former math tutors already - me, and ihateschool.

My first degree was in Mathematics. I broke it down for you earlier in this thread.

Would this make it easier?
______________________________________

I'll get rid of the (9+3) by simplifying it down to 12.

Like subtraction, division must not be performed in just any order - barring parentheses, it must be performed from left to right.

However, multiplication may be performed in any order.

As correctly noted by others, division by 2 is simply multiplication by its reciprocal, ½:

Thus

48 ÷ 2 ?? 12​

becomes

48 ?? ½ ?? 12​

Which may be evaluated in whatever order you like. For example, this one:

48 ?? 12 ?? ½​

48 ?? 12 = 576, and 576 ?? ½ = 288​

Or this one, if you prefer:

½ ?? 12 ?? 48​

½ ?? 12 = 6, and 6 ?? 48 = 288​

Yeah I worded that wrong. I have serious issues with the way the problem is presented. It is horribly written and nobody in any math or science field would express that equation in such terms. Which is why people are getting different answers. I posted a link to a physics forum where they are also in disagreement. Physicist are pretty much mathematicians by default.

It really needs to show brackets when doing this. The divided by sign can also be written as a fraction. However, the way it is written if you put it in fraction form it would be 48 / 2(9+3) which is clearly 2.

The laws of Algebra and Calculus tell us there should be no problem manipulating that problem, we should get the same answer, but clearly we do not. It's a bullshit problem, and I still say the point is to prove how important communications is.

 

[maniclion]

No, they're not. That's the beauty of mathematics. Right or wrong isn't a matter of opinion; it's a matter of logic.

You've heard from at least two former math tutors already - me, and ihateschool.

My first degree was in Mathematics. I broke it down for you earlier in this thread.

Would this make it easier?
______________________________________

I'll get rid of the (9+3) by simplifying it down to 12.

Like subtraction, division must not be performed in just any order - barring parentheses, it must be performed from left to right.

However, multiplication may be performed in any order.

As correctly noted by others, division by 2 is simply multiplication by its reciprocal, ½:

Thus

48 ÷ 2 ?? 12​

becomes

48 ?? ½ ?? 12​

Which may be evaluated in whatever order you like. For example, this one:

48 ?? 12 ?? ½​

48 ?? 12 = 576, and 576 ?? ½ = 288​

Or this one, if you prefer:

½ ?? 12 ?? 48​

½ ?? 12 = 6, and 6 ?? 48 = 288​

Oh yeah, well some still think it's 2 so what are you gonna do about that?

Some are trying to claim there is some Law of Inference that says since the multiplication sign is absent and the 2 is butted up to the () it is inferred it should be done together.....but I have never seen this Law of Inferrence...not even when I learned Programming Languages....

 

[vortrit]

Hey math homos!

 

[hoyle21]

Oh yeah, well some still think it's 2 so what are you gonna do about that?

Some are trying to claim there is some Law of Inference that says since the multiplication sign is absent and the 2 is butted up to the () it is inferred it should be done together.....but I have never seen this Law of Inferrence...not even when I learned Programming Languages....

I actually believe, based on the picture of the TI-85 and TI-86 side by side with different answers there may be something to that, but I think it is programming not an official math rule. I have never heard of such a thing.

I also never heard you had to go from left to right when working a problem. There should be no difference in the order of subtraction and addition, or multiplication and division. Another reason this is a bullshit problem.

 

[Built]

Yeah I worded that wrong. I have serious issues with the way the problem is presented. It is horribly written and nobody in any math or science field would express that equation in such terms. Which is why people are getting different answers. I posted a link to a physics forum where they are also in disagreement. Physicist are pretty much mathematicians by default.

It really needs to show brackets when doing this. The divided by sign can also be written as a fraction. However, the way it is written if you put it in fraction form it would be 48 / 2(9+3) which is clearly 2.

The original question was written with a division operator, not a slash:

48÷2(9+3)

Exchanging the divisor for a slash isn't enough to turn 2(9+3) into a denominator. In order to do so, it would still require square brackets. Without them, the slash is simply alternative notation to the division operator "÷".

Now, had it been written like this:

48÷[2(9+3)]​

or even like this:

48/[2(9+3)]​

then yes, it would indeed have been equivalent to the fraction below:

. 48 .
2(9+3)​

The laws of Algebra and Calculus tell us there should be no problem manipulating that problem, we should get the same answer, but clearly we do not. It's a bullshit problem, and I still say the point is to prove how important communications is.

I didn't concern myself with any interpretation of its purpose. To me, it's just arithmetic.

 

[Built]

I also never heard you had to go from left to right when working a problem. There should be no difference in the order of subtraction and addition, or multiplication and division.

Really?

So 10 - 7 is the same as 7 - 10?

How about 100 ÷ 2 and 100 ÷ 2?

Forgot about those, hey? Turns out that while multiplication and addition are open under commutativity, this is not the case for either division or subtraction - for which commutativity is closed.

I know, it's a bitch, but whaddya gonna do?

 

[hoyle21]

The original question was written with a division operator, not a slash:


Exchanging the divisor for a slash isn't enough to turn 2(9+3) into a denominator. In order to do so, it would still require square brackets. Without them, the slash is simply alternative notation to the division operator "÷".

Now, had it been written like this:

48÷[2(9+3)]​

or even like this:

48/[2(9+3)]​

then yes, it would indeed have been equivalent to the fraction below:

. 48 .
2(9+3)​

I didn't concern myself with any interpretation of its purpose. To me, it's just arithmetic.

÷, /, and X all represent the same function.
X

1 is the same as 1/2 is the same as 1÷2. The brackets should be there.
2

Its a BS problem

 

[hoyle21]

Really?

So 10 - 7 is the same as 7 - 10?

How about 100 ÷ 2 and 100 ÷ 2?

Forgot about those, hey? Turns out that while multiplication and addition are open under commutativity, this is not the case for either division or subtraction - for which commutativity is closed.

I know, it's a bitch, but whaddya gonna do?

no, you are changing the numbers, what Im saying is 6+3-4 =5
6-4+3=5

The order doesnt matter as long as the sign stays with the appropriate number. Same as multiplication and division.

Look I have taken math through Calc, Differential equations, and into Linear Algebra. I know what Im talking about. Its a BS problem

 

[Built]

The brackets should be there.

Hmmm... not quite. The brackets COULD be there.

In order for the answer to be 2, the brackets would have to be there.

Because they are not, the answer is 288.

 

[hoyle21]

So 10 - 7 is the same as 7 - 10?

How about 100 ÷ 2 and 100 ÷ 2?

to further illustrate my point, I didnt say the above

10-7 is however is the same as -7+10 (the plus sign in front of the 10 is implied)