48÷2(9+3) =

[7StringedBeast]

Sorry actually we are both wrong.

you subtract x from both sides.

so you have (10x) -x = 9.99 -x

so 10(x) - x = 9

You can't subtract an x out of that multiplication.

EDIT:  Never mind.  I seemed to have forgotten that 10x is actually x + x + x + x etc.  lol I've been out of math classes for far too long.

[kári]

What you said above your last line made no sense at all.

[rumborak]

I see, thanks. It also includes the proof I gave a few posts above... Does it also make use of the same tautology you are referring to?

It does seem to rely on the same thing, yeah. The key step is when you subtract 0.9999... from 9.99999...., where you are in the same kind of business of working with this incomplete notation. Even though, in that case it's not as blatant as the other one I find.

rumborak

[kári]

Really? I would've thought that it's no problem to write 9.99... as 9 + 0.99...
I thought the "key step" was 10*(0.99...) = 9.99...

[tjanuranus]

i can't believe the wrong answer is leading this poll WTF.

[mizzl]

i can't believe the wrong answer is leading this poll WTF.

This xD

[XJDenton]

To be honest I got it wrong before I looked up why. I would never write the equation like that so preference of operations rarely comes up for me.

[rumborak]

That's why I voted for "no definite answer". It's still bad syntax.

rumborak

[Scard]

In order of operations, division trumps multiplication. Always do the division first.

[rumborak]

It's always great to see someone come in and post something that has been shown to be wrong in the previous posts. Multiplication and division are of equal precedence, and you must disambiguate with brackets.

rumborak

[KevShmev]

I would think 288 would be correct, but I haven't taken a math class in like eight years, so I am going from memory as far as order of operations.

[lonestar]

 

Still at it, eh guys?

[Dimitrius]

Still at it, eh guys?

We're a prog forum, aren't we?

[Jamesman42]

Well, rumby, I will just disagree with you on that 0.999 business. But I really don't feel like arguing it

I asked some people today in the math field, they all initially said 2, and when I asked "Are you sure?", most changed their mind and came to 288.

[Orbert]

I see the 2(9+3) as one term, so the implied multiplication does in effect take precedence.

For example, if it was 48÷2x, you would definitely simplify 2x first, then divide 48 by the result.  It's not 48÷2*x.  The implied multiplication isn't the same in hierarchy, it comes in with higher priority.  It never even occurred to me to go left to right, because there's no multiplication sign there.  You divide by 2(9+3).

So the answer is 2.  Asking someone "Are you sure?" isn't just asking if they're sure; it makes them think that you know they're wrong and you're giving them another chance to get it right, so they switch to the only other possibility.

[kári]

According to the rules of math, the answer is 288. It's as simple as that. Whether it looks messed up or not, it's 288.

[LieLowTheWantedMan]

According to the rules of math, the answer is 288. It's as simple as that. Whether it looks messed up or not, it's 288.

[ScioPath]

Re: the 0.999... snafu:

Asking whether or not 0.999... = 1 is the same as asking whether 1/∞ = 0.

1 - 0.999... = 0.000...1
=10^-∞
=1/10^∞
=1/∞
IFF 1/∞ = 0, then 0.999... = 1.

The problem is, 1/∞ is debatable. One can say the answer is zero, an infinitesimally small number, or undefinable.

My answer is: yes, 0.99... is equal to 1, but only because we need it to be.

[XJDenton]

Re: the 0.999... snafu:

Asking whether or not 0.999... = 1 is the same as asking whether 1/∞ = 0.

1 - 0.999... = -0.000...1

Pretty sure you can't do that.

[Jamesman42]

So the answer is 2.  Asking someone "Are you sure?" isn't just asking if they're sure; it makes them think that you know they're wrong and you're giving them another chance to get it right, so they switch to the only other possibility.

But to me, math is concrete. Me asking them makes them look at it deeper and discover that there may be more to it. So I interjected a little doubt to their answer; I didn't say theirs was wrong. They all switched because they reasoned it out like I did in the end.

The problem is, 1/∞ is debatable. One can say the answer is zero, an infinitesimally small number, or undefinable.

My answer is: yes, 0.99... is equal to 1, but only because we need it to be.

In calculus, when we take limits for a variable approaching infinity, we do say that 1/∞ = 0. Just like 0.999 = 1, that is just what it is.

[Octawakeimages]

I say 2.  Yay for PEMDAS!  PLEASE excuse my dear aunt sally!!!   

[slycordinator]

I see the 2(9+3) as one term, so the implied multiplication does in effect take precedence.

So they'd be separate terms if I made it "2*(9+3)"?

And this seems like a circular argument. Why is it one term? Because implied multiplication takes precedence. Why does implied multiplication take precedence? Because I see it as one term.

[Quadrochosis]

48 / 2(9+3)
48 / ((2x9)+(2x3))
48 / (18 + 6)
48 / (24)
2

Where is the difficulty?

[lonestar]

I hearby declare both 2 and 288 to be correct, if only to save my sanity.

[bloop]

Sorry, that's not how the internet works.

[slycordinator]

48 / 2(9+3)
48 / ((2x9)+(2x3))
48 / (18 + 6)
48 / (24)
2

Where is the difficulty?

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

Where is the difficulty?

[LieLowTheWantedMan]

I say 2.  Yay for PEMDAS!  PLEASE excuse my dear aunt sally!!!   

Why is it no one seems to know how to do PEMDAS/BEDMAS?

[Jamesman42]

Where is the difficulty?

For the nth time, division and multiplication are in the same rank.

[Dimitrius]

Where is the difficulty?

For the nth time, division and multiplication are in the same rank.

Yes, but in the syntax that Quad wrote it, it is 2.

[Jamesman42]

Where is the difficulty?

For the nth time, division and multiplication are in the same rank.

Yes, but in the syntax that Quad wrote it, it is 2.

Oh, so he did a separate problem. Gotcha.

[The Degenerate]

It's 288. Regardless of PEMDAS/BEDMAS, multiplication and division are equal in the order of operations. So after doing the parenthesis, you go left to right.

[ScioPath]

Re: the 0.999... snafu:

Asking whether or not 0.999... = 1 is the same as asking whether 1/∞ = 0.

1 - 0.999... = 0.000...1

Pretty sure you can't do that.

Of course you can, it just reduces the argument. The 0.000...1 either represents an infinitely small number or zero, which is exactly what we are trying to determine. People who argue that 0.999... is not equal to 1 imply that 0.000...1 is in fact a number of measurable substance greater than zero, while those who argue that 0.999... is equal to 1 imply that 0.000...1 is zero. I do not agree that a number approaching a number, even to the point of being infinitely similar, can ever be equal to the number.

[Gorille85]

It's 37.

[Nic35]

It's 37.

[lonestar]

It's 37.