48÷2(9+3) =

[airdata]

The mathmyway website simplifies it to 48 over 2(9+3)

Also, the previous post I'd quoted seemed to sum it up pretty well by substituting X for 2 and set it = 288

48/X(9+3) = 288 is a false statement and therefore 288 is not the correct answer.

 

[rcpratt]

Replacing 2 with an x changes the equation. In order to find out the value of x, you have to follow a different order of operations than you do to evaluate the expression posed in the OP.

Not really. He's breaking the exact same rule when he distributes the x instead of multiplying the left side of the equation by x (to change the equation to 48*12=288*x).

 

[Paul98]

From physicsforum.com user RJS

Re: 48÷2(9+3)

Looking at it like this though:


48 ÷ x(9 + 3) = 288
48 ÷ 9x + 3x = 288
48/12x = 288
4/x = 288
4 = 288x
4/288 = x
1/72 = x


Would suggest that 288 is wrong, and that 2 is correct.

48 ÷ x(9 + 3) = 288
48 ÷ x*9 + 48 ÷ x*3 = 288
432 ÷ x + 144 ÷ x = 288
576 ÷ x = 288
576 = 288x
576 ÷ 288 = x
2 = x

now since I guess it isn't obvious substitute 2 in for x at the start. and we get

48 ÷ 2(9 + 3) = 288

would suggest that 288 is correct...

as you can see doing this is no different than what you would get if you just evaluated it. Doing that gives you the exact same problem as what was written before... so is useless.

 

[airdata]

that 288 is correct to show that the real answer is 2 ?

 

[purbeast0]

From physicsforum.com user RJS

48 ÷ x(9 + 3) = 288
48 ÷ 9x + 3x = 288
48/12x = 288
4/x = 288
4 = 288x
4/288 = x
1/72 = x

umm ... your math is wrong.

this is elementary shit too.

wow the fail in this thread is so fucking fail it amazes me.

 

[Paul98]

that 288 is correct to show that the real answer is 2 ?

lol, I ended with x = 2 NOT the equation 48/2(9+3) = 2.

Go to the first equation substitute 2 in for x which is what I solved for. And you get 48/2(9+3) = 288.

 

[airdata]

umm ... your math is wrong.

this is elementary shit too.

wow the fail in this thread is so fucking fail it amazes me.

I was just quoting a post from another forum, thought that was pretty clear

Seems like this is split 50/50 on most forums it's been posted in though.

But again... does it matter? absolutely not. I'd rather clear up my hard drive to remember more important things than things like algebra.

 

[airdata]

A couple of other golden posts found on other boards :

Re: 48÷2(9+3)
It can be written that way if you assume a particular meaning- but the expression as given is ambiguous and cannot be correctly evaluated without assuming something not given.

You, basically, assumed the "correct" answer was 288 and, no surprise, arrived at that answer.

 

[SP33Demon]

...but most mathematicians would agree that the implied multiplication takes precedence over the division.

No, they don't. Show me a reputable source that says such a thing, and your head doesn't count. It's always left to right when division and/or multiplication is involved. Aren't you a teacher as well? lmao

 

[airdata]

No, they don't. Show me a reputable source that says such a thing, and your head doesn't count. It's always left to right when division and/or multiplication is involved. Aren't you a teacher as well? lmao

I've seen alot of people talking about how implied multiplication takes precedence over regular pemdas. 2(9+3) may as well be in brackets because it's a single part of the problem.

That being said, all reports are in that this is simply a clever troll thread to get people to waste time and argue over a problem that can be solved multiple ways.

Is it a Bull... or is a robot reading a book...

 

[Kyteland]

As a mathematician and computer scientist all I can say is that you can't evaluate the expression without first providing a definition for the function 2(x). Evaluating that expression as an implied multiplication is formally incorrect. Rewriting it symbolically you get x/f(y+z).

However, assuming it is implying 48/2*(9+3) then the answer is of course 288.

 

[SP33Demon]

I've seen alot of people talking about how implied multiplication takes precedence over regular pemdas.

It doesn't, and where are they learning this because surely it's not school. If the equation said 2(3a + 4b), then yes. There is nothing to imply the units in the parens are different without the a and b, hence they are added.

 

[ussfletcher]

How have we as a species come so far, with something this basic being contested?

 

[sdifox]

How have we as a species come so far, with something this basic being contested?

the smart people are dragging us along, kicking and screaming :biggrin:

 

[her209]

48 / 2 (9 + 3)
48 / (18 + 6)
48 / 24
2

 

[GundamW]

Can I change my vote to 2? I want to be the vote to tip this poll to the retard side.....err... I mean the mathematically challenged side.

 

[Glitchny]

48 / 2 (9 + 3)
48 / (18 + 6)
48 / 24
2

no...

48 / 2 (9 + 3)
48 / 2 (12)
24 (12)
288

 

[IHateMyJob2004]

As a mathematician and computer scientist all I can say is that you can't evaluate the expression without first providing a definition for the function 2(x). Evaluating that expression as an implied multiplication is formally incorrect. Rewriting it symbolically you get x/f(y+z).

However, assuming it is implying 48/2*(9+3) then the answer is of course 288.

As a mathematician, you should know this is ambiguous.

As a computer scientist, I hope you realize that this is equivalent = to:
(48/2)*(9+3) = 288

Because in computer science, multiplication and division are equivalent and as such operated on from left to right.

 

[Locut0s]

Equation? Are you the first person in this thread to call that expression an equation?

Incidentally, upon further thought, I agree with Matthiasa - there's no real consensus in mathematics for such a poorly written expression, but most mathematicians would agree that the implied multiplication takes precedence over the division.

FUCK YES Thanks for agreeing. Nice to have a math teacher agree that this is a common convention but not a HARD rule!

 

[purbeast0]

48 / 2 (9 + 3)
48 / (18 + 6)
48 / 24
2

stop trolling plz thx!

 

[DrPizza]

No, they don't. Show me a reputable source that says such a thing, and your head doesn't count. It's always left to right when division and/or multiplication is involved. Aren't you a teacher as well? lmao

2/xy would be interpreted by most people to mean 2 divided by the product of x and y. Not 2y/x
However, I don't think I've EVER seen such an ambiguous expression in any math textbook.

 

[DisgruntledVirus]

2/xy would be interpreted by most people to mean 2 divided by the product of x and y. Not 2y/x
However, I don't think I've EVER seen such an ambiguous expression in any math textbook.

It's like the "I before E except after c" type rules in English that is a general "rule" but has exceptions to it.

2/xy could be evaluated different ways as well depending on how you interpret it. It could read:

(2/x)*y
2/(xy)

Both of which would provide different results. Common understanding would evaluate that as 2/(xy) instead of (2/x)*y though. Still the problem in the OP is bad math.

 

[MovingTarget]

2/xy would be interpreted by most people to mean 2 divided by the product of x and y. Not 2y/x
However, I don't think I've EVER seen such an ambiguous expression in any math textbook.

What do you think your students would say? It certainly would make for an interesting conversation about ambiguity.

 

[SP33Demon]

2/xy would be interpreted by most people to mean 2 divided by the product of x and y. Not 2y/x
However, I don't think I've EVER seen such an ambiguous expression in any math textbook.

Without the parens, just follow the fcking rule. It's not rocket science. 2/y*x. There, was that so hard? I understand what you're saying, but it's black and white unless the paren is there.

Here, I'll even substitute real values to make it easier so you're not confused by letters:

x = 2
y = 3

2/2*3 = 3
and
2/(2*3) = 1/3

 

[DrPizza]

Okay, who here would interpret 6x² ÷ 2x to get 3x^3? Anyone who's not a troll?

Go ahead, speedemon, stick in 2's and 3's. The rest of the world is going to get 3x, not 3x^3.