48/2(9+3) = ???

[Mutant]

Originally Posted by TheWinterSnow

Maybe not all Americans but most. I know I was taught to simplify expressions by using the associative property and distributive property.

I don't blame you, it is not your fault.

Without any hostile feelings i just ask you to quote, link, post a scan to any respectable publication saying that it has more weight than PE(MD)(AS).

[Mutant]

a + b
----- =  (a + b) / (c + d)
c + d

    b
a + - - d =  a + b / c - d 
    c
(the division is already higher than addition and substraction so no need for a bracket there)



a / (b * c)
----------- =  a / (b * c) / d
     d
(the left hand side division is higher than the right hand side division so again no need for a bracket)


     b * c
a / --------- =  a / [(b * c) / (a + d ^ c)]
    a + d ^ c

[P-E]

You guys are putting way too much thought into this.

48/2(9+3) is not equal to 48/(2(9+3))
48/2(12) is not equal to 48/(24)
24(12) is not equal to 2
288 is not equal to 2

The answer is 288, as 2 and (9+3) aren't in the same bracket.
End of thread please?

[motomoto]

Originally Posted by P-E

You guys are putting way too much thought into this.

48/2(9+3) is not equal to 48/(2(9+3))
48/2(12) is not equal to 48/(24)
24(12) is not equal to 2
288 is not equal to 2

The answer is 288, as 2 and (9+3) aren't in the same bracket.
End of thread please?

This^

[Mutant]

Originally Posted by P-E

End of thread please?

LOL No way ! Not until the poll is at least 50% to 50%

Come on ! This forum is available for everyone through Google and i don't want people to think that metalhead sound guys are mostly "2" !!!

[Sickan]

Originally Posted by Mutant

LOL No way ! Not until the poll is at least 50% to 50%

Come on ! This forum is available for everyone through Google and i don't want people to think that metalhead sound guys are mostly "2" !!!

This makes me want to delete my account.

[JBroll]

Originally Posted by Audiosprite

yeah, mathematically there are some unnecessary ones in there but that's exactly how i'd do it too. safe and organized.

It is very hard to lose clarity by parenthesizing carefully - you have to try to screw things up.

Jeff

[Hez]

dani's post earlier in the thread cleared it up for me. binding left to right definitely seems like the most logical way to do it. mutant was definitely being antagonistic earlier on, so i stand by my accusation ;D not that the "2" side wasn't slinging shit either.

it's quite interesting how some people (myself inclusive) bind the multiplication more strongly than anything else due to our upbringing. maybe emphasizing the left-to-right behaviour once operators of the same level remain in the equation would be useful in maths classes (i don't think i was ever taught this) now that PCs are being used more and more frequently. not that this rule doesn't apply outside PCs, it just seems that the issue is much more likely to come up while typing maths rather than hand writing it or using special software.

hopefully this thread will teach anybody involved in any mathematical subject to diligently use as many parentheses as required. i personally over-parenthesize the crap out of anything, and bitch+moan at anybody that complains at me.

glad that JBroll and dani gave some really clear and concise programmer-like explanations to clear it up.

a last thing: dani mentioned that in a compiler class they were taught to bind division more strongly than multiplication in expressions otherwise requiring left-to-right parsing to evaluate correctly; what's your opinion on that, JBroll?

[JBroll]

Originally Posted by JeffTD

To be fair, "they" don't teach much of anything in Texas.

Don't even start with that... math education *everywhere* in this country is *absolutely abysmal*.

Jeff

[ParsonsMatt]

This thread makes me sad for math education

[Mutant]

I'll try to identify all the causes of giving the wrong 2 answer.

1. Assuming that the division sign and the fractional bar are the same:
A division sign requires parentheses to tell you where it ends.

(a+b/c)/(a+d)

A fractional bar works like a vinculum - it shows you what is grouped above and below it, so you don't have to put parentheses there.

a+b/c
-----
 a+d

If you tried to omit the parentheses in the inline format with a division sign, you would write something completely different.
They are not the same. Period.

---------------
2. Inability to convert from inline format to vertical format:
a+b/c+d

Is not

a + b
-----
c + d

It will always be just

 
     b
a + --- + d
     c

---------------
3. The unfortunate mnemonics of PEMDAS wich are understood by some, as Parentheses, then Exponents, then Multiplication, then Division, then Addition, then Substraction:

It should be PEMaDAaS or Parentheses, then Exponents, then Multiplication and Division, then Addition and Substraction.

Multiplication and Division are equal, because

2*2=2*(2/1)=2/(1/2)

And Addition and Substraction are equal, because

2+2=2-(-2)

So if we have Multiplication and Division signs, we go from left to right.

And if we have Addition and Substraction signs, we go from left to right too.

---------------
4. Breaking the basic, holy, unbreakable rule of PEMaDAaS with the distributive property "oneness":
We can't break PEMaDAaS with anything, or we would arrive at the whole new twisted and wrong universe of wrong mathematics.

2(9+3)=(2*9)+(2*3)=24
We can use the distributive property here.

2+2(9+3)=2+(2*9)+(2*3)=26
And here too.

2/2(9+3)=2/2*12=1*12=12
But not here, because the division which is higher than multiplication in PEMaDAaS ripped the 2 and the inside of the bracket apart.

2^2(9+3)=2^2*12=4*12=48
And again not here, because the exponent sign, or as we say in Europe "to the power of" sign, powerfully stole the 2 from the (9+3).

---------------
5. Trying to imagine what the author of the equation had in mind, when he was writing it, instead of just solving the problem exactly as it is written:

E=mc^2 is not E=(mc)^2
People could die if some construction engineer assumed these parentheses around m and c just "because they are written together".

a+b/c+d is not (a+b)/(c+b)
I saw some "scientist" on another forum, trying to tell us that it could be justified to imagine parentheses there.
Interpreting a formula to "really" mean that addition without parentheses around it comes before division ??? No words... Just a big, loud LOL !!!

---------------
6. Trolling.
Well... hehehe.

[Limak]

To be fair the guy who decided to post this problem first was trolling genius. He knew US people would use the distribution thingy and EU people would apply straight PEMDAS. He also knew some calculators would also solve this differently.

And since math is actually a serious business and everyone always suddenly claims to be math/science major in those kind of threads this was perfect bait. This would include major namecalling etc as we can see on the first page of this very thread.

I applaud to the greatest troll of all times

[ParsonsMatt]

Originally Posted by Limak

To be fair the guy who decided to post this problem first was trolling genius. He knew US people would use the distribution thingy and EU people would apply straight PEMDAS. He also knew some calculators would also solve this differently.

And since math is actually a serious business and everyone always suddenly claims to be math/science major in those kind of threads this was perfect bait. This would include major namecalling etc as we can see on the first page of this very thread.

I applaud to the greatest troll of all times

Even if you were to distribute, you would be distributing (48/2) to (9+3). Not 2.

[LeSedna]

Originally Posted by ParsonsMatt

Even if you were to distribute, you would be distributing (48/2) to (9+3). Not 2.

You are 100% making the point of the post you are quoting

[SimonSez]

Originally Posted by Limak

To be fair the guy who decided to post this problem first was trolling genius. He knew US people would use the distribution thingy and EU people would apply straight PEMDAS. He also knew some calculators would also solve this differently.

And since math is actually a serious business and everyone always suddenly claims to be math/science major in those kind of threads this was perfect bait. This would include major namecalling etc as we can see on the first page of this very thread.

I applaud to the greatest troll of all times

+1

I applaud thee.

[xFkx]

Well... all big "american" scientific discoveries were made by soviet and german scientists...

[Skinny Viking]

^ yeah ...

like flight for example

either way, it sure as shit wasn't a Pole

[xFkx]

Originally Posted by Skinny Viking

^ yeah ...

like flight for example

either way, it sure as shit wasn't a Pole

great example, Otto Lilienthal was a great pioneer


u mad ?

[MarcusGHedwig]

Pretty sure the internet was an American invention (and UNIX, and the ENIAC, and Microsoft/Apple - hell, pretty much all of the fundamental technologies of the information age)

[Skinny Viking]

Originally Posted by xFkx

great example, Otto Lilienthal was a great pioneer


u mad ?

puh! That was gliding ... squirrels been doing that shit forever

hahahaha

never mad dude ... just waiting to see how long it would take for you to jump back in and see who took your bait

[xFkx]

Originally Posted by Skinny Viking

puh! That was gliding ... squirrels been doing that shit forever

hahahaha

never mad dude ... just waiting to see how long it would take for you to jump back in and see who took your bait

trolling is an artform, needs practice

man, i've been sitting way too much on HCAF lately, fried my brain, but it's pretty entertaining

[Altitudes]

My initial answer was 2, but upon further reflection I can see that it could also be 288. FUCKING PARENTHESIZES, HOW DO THEY WORK?

[Audiosprite]

Originally Posted by MarcusGHedwig

Pretty sure the internet was an American invention (and UNIX, and the ENIAC, and Microsoft/Apple - hell, pretty much all of the fundamental technologies of the information age)

you mean al gore

[Altitudes]

Also, just a thought: Is 48/2(9+3) =/= 48/(2(9+3)) ? I'm not going through 8 pages to see if this has been brought up.

I think this is the root cause of all our woes

Edit: I think the answer is 288. Took me long enough (hey, I want to be certain )

[JBroll]

The tricky bit is that some assume that parentheses are implied as you wrote. (48/2)*(9*3) is what should come out (barring, of course, any other conventions that are occasionally made to prevent this sort of thing), so that's exactly what went wrong.

Jeff