REVscene - Vancouver Automotive Forum

StylinRed · 04-13-2011, 06:07 AM

Presto · 04-13-2011, 07:35 AM

Good morning. Looks like another slow work day, so here I am. How about some algebra?

The statement below is true.
48 ÷ 2(3+9) = 288

In order to demonstrate that it is so, I'll express 3+9 as 'x'.
48 ÷ 2(x) = 288

Now, following bedmas, I'll divide 48 by 2
24(x) = 288

To isolate the (x), I'll divide both sides by 24
x=12 = 3+9

Let's try the same thing but with an answer of 2
This time the statement below is false. 'x' =/= (3+9)
48 ÷ 2(3+9) = 2

In order to demonstrate that it is so, I'll express 3+9 as 'x'.
48 ÷ 2(x) = 2

Now, following bedmas, I'll divide 48 by 2
24x = 2

To isolate the (x), I'll divide both sides by 24
x = 1/12 (one-twelfth)
since we know that 'x' should be (3+9), then this statement is wrong..

StylinRed · 04-13-2011, 07:50 AM

^^ think its been settled a billion times already... with math instructional sites... but those that think its 2 will still think its 2

Soundy · 04-13-2011, 07:56 AM

Quote:

Originally Posted by taylor192

Did you read what I wrote? The physics are far from easy. You have to design and build a conveyor belt capable of going to infinity in zero time, and account for the real world losses.

Okay: IN THE REAL WORLD, the physics are dead simple.

If you eliminate inertia and momentum, sure things change. You also have to eliminate friction, then, to keep it fair... and without friction in the wheel bearings, even a conveyor that instantly accelerates to infinite velocity wouldn't launch the plane backward. While we're at it, let's eliminate Newton altogether. Heck, let's recalculate it in a one-dimensional universe.

AzNightmare · 04-13-2011, 08:00 AM

wow, can't believe this went to page 8...

taylor192 · 04-13-2011, 08:14 AM

Quote:

Originally Posted by Soundy

Okay: IN THE REAL WORLD, the physics are dead simple.

If you eliminate inertia and momentum, sure things change. You also have to eliminate friction, then, to keep it fair... and without friction in the wheel bearings, even a conveyor that instantly accelerates to infinite velocity wouldn't launch the plane backward. While we're at it, let's eliminate Newton altogether. Heck, let's recalculate it in a one-dimensional universe.

There's no momentum, cause the plane starts in a stationary position relative to the rest of the world, its only moving relative to the conveyor belt.

That's just one thing wrong with your post./ I can blow a few more holes in it, yet I won't cause its not worth it. Its a word problem, not a physics problem, since the real world implementation varies too much.

Presto · 04-13-2011, 08:21 AM

The conveyor belt is a red herring. It's all about the air being moved around the plane. Whether it's prop driven, or jet driven, it'll still move air. With thrust happening, Newton's 3rd law of motion says something is going to happen:

Quote:

If a force acts upon a body, then an equal and opposite force must act upon the body that exerts the force.

Where's the opposing force of the engine going?

Presto · 04-13-2011, 08:38 AM

Quote:

Originally Posted by TRDood

He inversed only the parts he "wanted".
Posted via RS Mobile

Yeah.. it's some of that black, voodoo magic that I used to suit my purposes.

FACT: Division is the inverse of multiplication

So, instead of 4 ÷ 2, I can change the division operation into a multiplication operation by inverting the divisor(2), then I can multiply it. Now I have 4 * ½. And the answer is the same. I did this to bring a bit more clarity to the equation since people mistake the divide(÷) for a vinculum, and throws off their BEDMAS.

46_valentinor · 04-13-2011, 08:47 AM

Quote:

Originally Posted by Presto

Good morning. Looks like another slow work day, so here I am. How about some algebra?

The statement below is true.
48 ÷ 2(3+9) = 288

In order to demonstrate that it is so, I'll express 3+9 as 'x'.
48 ÷ 2(x) = 288

Now, following bedmas, I'll divide 48 by 2
24(x) = 288

To isolate the (x), I'll divide both sides by 24
x=12 = 3+9

Let's try the same thing but with an answer of 2
This time the statement below is false. 'x' =/= (3+9)
48 ÷ 2(3+9) = 2

In order to demonstrate that it is so, I'll express 3+9 as 'x'.
48 ÷ 2(x) = 2

Now, following bedmas, I'll divide 48 by 2
24x = 2

To isolate the (x), I'll divide both sides by 24
x = 1/12 (one-twelfth)
since we know that 'x' should be (3+9), then this statement is wrong..

the way you did 48 ÷ 2(x) = 2 is incorrect because if you recall, we treated 2(x) as one in order to get 2 as the final answer. it would be 2x and you would not have been able to divide 48 by 2x to get 24x. the correct way would have been:
48 2
___ = ___ which simplifies to 48 = 4x which equals to 12 = x

2x 1

however, the way you did 48 ÷ 2(x) = 288 is correct since you treated the 2(x) as 2*x which makes it possible for you to divide 48 by 2.

ae101 · 04-13-2011, 08:48 AM

48÷2(9+3)= :

there its done, its over 9000

Oleophobic · 04-13-2011, 08:50 AM

Quote:

Originally Posted by Presto

....more useless proofs....

Stop with the proofs as they are meaningless seeing as this is an interpretation or better yet, a communication issue. (Ignore the folks trying to prove it's 2 by incorrectly using the B in BEDMAS).

To put it another way, we are taught to use / instead of the division symbol, and that division is really a fraction. So it really boils down to how people assume the question would look if it were written with an over / under division bar. As a fraction, there is ambiguity as I've mentioned earlier in one of my posts.

Presto · 04-13-2011, 09:12 AM

Quote:

Originally Posted by r6_4life

the way you did 48 ÷ 2(x) = 2 is incorrect because if you recall, we treated 2(x) as one in order to get 2 as the final answer. it would be 2x and you would not have been able to divide 48 by 2x to get 24x. the correct way would have been:
48 2
___ = ___ which simplifies to 48 = 4x which equals to 12 = x

2x 1

however, the way you did 48 ÷ 2(x) = 288 is correct since you treated the 2(x) as 2*x which makes it possible for you to divide 48 by 2.

2(x) = 2x = 2*x =/= (2x)
You're trying to put brackets around 2x which translates the original equation to: 48÷[2(9+3)]

Multiplication is multiplication, and has the same priority as division. Ambiguity is when you introduce this implied multiplication as a priority, which is NOT standard convention. Some texts and calculators may do it, but it's not universally accepted, unlike BEDMAS.

The OP purposefully used a division(÷) sign, which I believe, is for clarity in dealing with an equation on one line. To properly express the equation as a fraction, it, again, needs to look like this:

48
__*(3+9)
2

NOT

48
__
2(3+9)

The fuckin' Rolls Royce is white, and the people that keep trying to thwart order of operations are wearing pink, Lady-Gaga glasses. Let me know when you decide to take them off, and you'll see the Rolls isn't pink.

twitchyzero · 04-13-2011, 09:24 AM

Quote:

Originally Posted by Presto

The fuckin' Rolls Royce is white, and the people that keep trying to thwart order of operations are wearing pink, Lady-Gaga glasses. Let me know when you decide to take them off, and you'll see the Rolls isn't pink.

Quote:

Originally Posted by Great68

Wow with the way Presto is going on about this you'd think we're pissing on his Doctorate of Mathematics paper.

You just keep proving Great68's point.

Anyways you can keep using endless amounts of facepalm emoticon for people coming up with answer of 2 but you'll still get both answers even from math majors/professors...FFS even calculators when the exact same equation is punched in as you pointed out.

Presto · 04-13-2011, 09:27 AM

Awesome. I'm not here to disprove his point, though. So, more power to you for being a great spectator.

Grandmaster TSE · 04-13-2011, 09:35 AM

we got ourselves some mathemagicians here

blagh · 04-13-2011, 09:36 AM

according to the poll atleast the majority of revscene arent fools

JSilver · 04-13-2011, 10:55 AM

SpuGen just trolled us all.

cowabunka · 04-14-2011, 10:13 PM

2

Spy228 · 04-14-2011, 11:01 PM

lol, can't believe how many people are going to great length's to try and explain their incorrect answer of 2.

Do not pass go, do not collect $100÷2(5-1).

Quote:

Originally Posted by T.T

Stop with the proofs as they are meaningless seeing as this is an interpretation or better yet, a communication issue. (Ignore the folks trying to prove it's 2 by incorrectly using the B in BEDMAS).

To put it another way, we are taught to use / instead of the division symbol, and that division is really a fraction. So it really boils down to how people assume the question would look if it were written with an over / under division bar. As a fraction, there is ambiguity as I've mentioned earlier in one of my posts.

No, this is not an interpretation or a communication issue. You said this multiple times now. This is math, and there is only one way to read this. You can not assume additional brackets or w/e your fraction explanation is that doesn't make sense. Oh and btw, the point of proofs is to prove something, and that's exactly what they do. Just because you are not used to seeing it written in this form, does not make math function in a different way.

cowabunka · 04-15-2011, 02:58 AM

6(8) ÷ 2(12) = 2 or 288?

LiquidTurbo · 04-15-2011, 03:28 AM

Somebody lock this thread up. Haha.
Posted via RS Mobile

goo3 · 04-15-2011, 04:24 AM

Generally accepted by the internet:

48/2*(9+3) = 288
48/2(9+3) = ambiguous

/thread

Mining · 04-15-2011, 04:44 AM

Quote:

Originally Posted by Presto

2(x) = 2x = 2*x =/= (2x)
You're trying to put brackets around 2x which translates the original equation to: 48÷[2(9+3)]

Multiplication is multiplication, and has the same priority as division. Ambiguity is when you introduce this implied multiplication as a priority, which is NOT standard convention. Some texts and calculators may do it, but it's not universally accepted, unlike BEDMAS.

The OP purposefully used a division(÷) sign, which I believe, is for clarity in dealing with an equation on one line. To properly express the equation as a fraction, it, again, needs to look like this:

48
__*(3+9)
2

NOT

48
__
2(3+9)

The fuckin' Rolls Royce is white, and the people that keep trying to thwart order of operations are wearing pink, Lady-Gaga glasses. Let me know when you decide to take them off, and you'll see the Rolls isn't pink.

Like I said before, D and M are interchangeable just as A and S are too.
Ever heard of PEMDAS?

you can write BEDMAS as, BEDMSA, BEMDAS, BEMDSA. they are all correct.

If you take this question to a math professor they will tell you both are correct answers depending on your interpretation (meaning its ambiguous)

Spy228 · 04-15-2011, 08:09 AM

Quote:

Originally Posted by Asmodeus

Like I said before, D and M are interchangeable just as A and S are too.
Ever heard of PEMDAS?

you can write BEDMAS as, BEDMSA, BEMDAS, BEMDSA. they are all correct.

You are correct, but then fail follow those rules correctly. The reason each pair is interchangeable is because neither operation has priority over each other. Therefore, the equation is calculated left to right. It is incorrect to start in the middle or right hand side of the equation just like it is incorrect to start reading an english word from the middle or right. Only one solution.

StylinRed · 04-15-2011, 09:35 AM

Quote:

Originally Posted by Asmodeus

Like I said before, D and M are interchangeable just as A and S are too.
Ever heard of PEMDAS?

you can write BEDMAS as, BEDMSA, BEMDAS, BEMDSA. they are all correct.

If you take this question to a math professor they will tell you both are correct answers depending on your interpretation (meaning its ambiguous)

do people even read the thread.... this has been posted a dozen times already in the thread but i'll post the one i did on the last page again

Quote:

Mnemonics are often used to help students remember the rules, but the rules taught by the use of acronyms can be misleading. In Canada the acronym BEDMAS is common. It stands for Brackets, Exponents, Division, Multiplication, Addition, Subtraction. In other English speaking countries, Brackets may be called Parentheses, or symbols of inclusion and Exponentiation may be called either Indices, Powers or Orders, and since multiplication and division are of equal precedence, M and D are often interchanged, leading to such acronyms as BIMDAS, BODMAS, BOMDAS, BERDMAS, PERDMAS, PEMDAS, and BPODMAS.

These mnemonics may be misleading, especially if the user is not aware that multiplication and division are of equal precedence, as are addition and subtraction. Using any of the above rules in the order "addition first, subtraction afterward" would also give the wrong answer.

10 - 3 + 2 \,

The correct answer is 9, which is best understood by thinking of the problem as the sum of positive ten, negative three, and positive two.

10 + (-3) + 2 \,

There is a new mnemonic featured in Danica McKellar's books Math Doesn't Suck[2] and Kiss My Math[3] that does address this very issue: "Pandas Eat: Mustard on Dumplings, and Apples with Spice." The intention being that Mustard and Dumplings is a "dinner course" and that Apples and Spice is a "dessert course." Then it becomes not a linear string of operations to do one after the other, but rather the "dinner course" operations are considered together and performed left to right, and then addition and subtraction are considered together, again performed again left to right.

http://en.wikipedia.org/wiki/Order_of_operations

http://www.mathgoodies.com/lessons/v...perations.html

http://www.mathgoodies.com/lessons/v...exponents.html

Quote:

How Do I Remember It All ... ? PEMDAS !

P
Parentheses first
E
Exponents (ie Powers and Square Roots, etc.)
MD
Multiplication and Division (left-to-right)
AS
Addition and Subtraction (left-to-right)

Divide and Multiply rank equally (and go left to right).

Add and Subtract rank equally (and go left to right)

After you have done "P" and "E", just go from left to right doing any "M" or "D" as you find them.

Then go from left to right doing any "A" or "S" as you find them.

Note: in the UK they say BODMAS (Brackets,Orders,Divide,Multiply,Add,Subtract), and in Canada they say BEDMAS (Brackets,Exponents,Divide,Multiply,Add,Subtract). It all means the same thing! It doesn't really matter how you remember it, just so long as you get it right.

http://www.mathsisfun.com/operation-order-pemdas.html