48÷2(9+3) = ??? -- VOTE!! Poll Added

[TramFan3]

again, the fact is that there isn't a definitive correct answer.

This is incorrect. There is a definitive answer and it is 288.

 

[thefatguy]

If you really meant

it should be written as 48/(2(9 + 3)). That forces the multiplication to be performed before the division.

48 should be divided by both the 9+3 and the 2, giving you 2.

Math teachers be dammed!

REAL WORLD APPLICATION

Gallons per hour = capacity / weight of water * change in temperature

GPH = Q/8.33 (T2-T1)

given capacity of 10,000 BTU and a temp change of 10 degrees,

GPH = 10000/ 8.3 * 10

GPH = 120gph, not 12048gph

 

[IndyManning18]

everyone involved needs to enjoy this


[youtube:1jbplso8]http://www.youtube.com/watch?v=rLprXHbn19I[/youtube:1jbplso8]

What a great bit!
:lol: :lol: :lol: :lol: :lol:

 

[TramFan3]

If you really meant

it should be written as 48/(2(9 + 3)). That forces the multiplication to be performed before the division.

48 should be divided by both the 9+3 and the 2, giving you 2.

Math teachers be dammed!

\

This is true. But that isnt what he meant.

The expressions

48/2(9+3) and 48/(2(9+3)) are not the same things.

 

[thefatguy]

This is true. But that isnt what he meant.

The expressions

48/2(9+3) and 48/(2(9+3)) are not the same things.

Not to me....anything under the / is the denominator. This is math v algebra. Math sucks, algebra rules!\


AGAIN

REAL WORLD APPLICATION

Gallons per hour = capacity / weight of water * change in temperature

GPH = Q/8.33 (T2-T1)

given capacity of 10,000 BTU and a temp change of 10 degrees,

GPH = 10000/ 8.3 * 10

GPH = 120gph, not 12048gph

 

[Guest]

This is true. But that isnt what he meant.

The expressions

48/2(9+3) and 48/(2(9+3)) are not the same things.

Not to me....anything under the / is the denominator. This is math v algebra. Math sucks, algebra rules!\


AGAIN

REAL WORLD APPLICATION

Gallons per hour = capacity / weight of water * change in temperature

GPH = Q/8.33 (T2-T1)

given capacity of 10,000 BTU and a temp change of 10 degrees,

GPH = 10000/ 8.3 * 10

GPH = 120gph, not 12048gph

Then put () around the 8.3*10, because writing it that way equals 12048

 

[scotty21690]

I ended up with 2 being the answer, after I did it in my head and not on a calculator. I can see how a lot of you got 288 though...Is this a trick question or something?

 

[scotty21690]

Ok never mind I was wrong the first time
[youtube:12q0jdpv]http://www.youtube.com/watch?v=wv19iAncrrQ&feature=player_embedded#at=18[/youtube:12q0jdpv]

Thanked!!


I saw that vid when it first came out and thought to myself...."THIS NEEDS WORDS!"

 

[TramFan3]

Not to me....anything under the / is the denominator. This is math v algebra. Math sucks, algebra rules!\

Algebra is math. I think you meant arithmetic, which is also still math.

The point is, mathematicians would compute

GPH = 10000/ 8.3 * 10

from left to right because of the order of operations.


You compute it differently because you know that in the equation you used, everything is in the denominator. And in most books it would be written with everything in the denominator, instead of as

GPH = 10000/ 8.3 * 10.

I guess it becomes a question of syntax.

 

[thefatguy]

Not to me....anything under the / is the denominator. This is math v algebra. Math sucks, algebra rules!\

Algebra is math. I think you meant arithmetic, which is also still math.

The point is, mathematicians would compute

GPH = 10000/ 8.3 * 10

from left to right because of the order of operations.


You compute it differently because you know that in the equation you used, everything is in the denominator. And in most books it would be written with everything in the denominator, instead of as

GPH = 10000/ 8.3 * 10.

I guess it becomes a question of syntax.

Thats all it is

a division sign is elementary school stuff. Real math is fractions, and understanding what goes on below the denominator.

÷
is not the same as
/

 

[scotty21690]

48÷2(9+3)


The way I was taught you do the parenthesis first. 48/2(12)

Then as you see:

48
__
2(12) or 24


48
__ = 2
24

 

[TramFan3]

a division sign is elementary school stuff. Real math is fractions, and understanding what goes on below the denominator.

÷
is not the same as
/

Real math isnt even fractions, trust me.

÷ is the same as / in every mathematical program that has ever been used.

In a book you would always use ÷.
On a computer you would always use /.

They still mean the same thing. Divide. And the order of operations is always in play.

 

[pigskincardboard]

My math degree says 288. Multiplication and division are equals in order of operations as are addition and substraction. Division is multiplication of an inverse and subtraction is addition of a negative.

The formula 48÷2(9+3) can be rewritten as 48x(1/2)(9+3) by substituting x(1/2) for ÷2. And 48 x 0.5 x 12 = 288.

So you're not classifying (9+3) as the denominator? It seems strange to view it as (48/2)*((9+3)/1) rather than 48/((2x)+(2y))

Mind you, we were also taught BEDMAS rather than this PEDMAS you speak of.

That is correct. If it were written 48÷(2(9+3)) then I would consider the (9+3) as part of the denominator. To me this comes down to a sloppily written formula. There should be an operator symbol between the 2 and the (. I believe it is correct to assume multiplication and rewrite the formula as 48÷2x(9+3). Evaluate inside the parentheses first resulting in 48÷2x12. Then since the remaining operations are all multiplication and division (which are the same), the formula is evaluated left to right.

That must be where I lost it. I don't think i've ever used a formula simply using pedmas like that. Quite frankly, I can't think of a single practical application for it. Yet, I can think of kazillions of practical formulas where you have to distribute the implied multiplier.

I think there's a reason why you stop doing one-lined math problems after grade 5 and simply use a numerator and denominator to do whatcha gotta do.

I bet I've written n!/r!(n-r)! a katrillion times and didn't think twice about it.

 

[scotty21690]

a division sign is elementary school stuff. Real math is fractions, and understanding what goes on below the denominator.

÷
is not the same as
/

Real math isnt even fractions, trust me.

÷ is the same as / in every mathematical program that has ever been used.

In a book you would always use ÷.
On a computer you would always use /.

They still mean the same thing. Divide. And the order of operations is always in play.

This is true.


15/5 = 15÷5

15
__ = 15÷5
5

 

[BunchOBull]

This thread is huge. I'm not going to take time to read it. I voted 288.

Multiplication and division are on the same order of operations and so are calculated left to right. The math inside the parenthesis comes first.

 

[TramFan3]

I bet I've written n!/r!(n-r)! a katrillion times and didn't think twice about it.

This goes back to what thefatguy was saying. Since you understand the context of what you were doing, you got lazy and wrote it that way.

But what umich said is right, technically the "choose" formula you wrote above should be

n!/(r!(n-r)!).

We're all guilty of it, I would probably type the choose formula the same way you did if say i were communicating with a probability professor. Because they would understand what i was trying to say.

 

[thefatguy]

Not so lazy way?

GPH = Q / (8.33lb/gal)(T2-T1)

because

Capacity Q = (GPH)(8.33lb/gal)(T2-T1)


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

because
(2)(9+3)(2) = 48



Now I'm really going to eat the thread

 

[TramFan3]

Not so lazy way?

GPH = Q / (8.33lb/gal)(T2-T1)

because

Capacity Q = (GPH)(8.33lb/gal)(T2-T1)


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

because
(2)(9+3)(2) = 48

Im not going to lie, i have no idea what this equation is. Thats the problem with pure math degree and leaning towards finance instead of physics. What I can tell you, is that in the equation

GPH = Q / (8.33lb/gal)(T2-T1)

if GPH = Q divided by everything,

then the proper mathematical syntax would be

GPH = Q / ((8.33lb/gal)(T2-T1))

 

[rehmus]

Not so lazy way?

GPH = Q / (8.33lb/gal)(T2-T1)

because

Capacity Q = (GPH)(8.33lb/gal)(T2-T1)


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

because
(2)(9+3)(2) = 48

Im not going to lie, i have no idea what this equation is. Thats the problem with pure math degree and leaning towards finance instead of physics. What I can tell you, is that in the equation

GPH = Q / (8.33lb/gal)(T2-T1)

if GPH = Q divided by everything,

then the proper mathematical syntax would be

GPH = Q / ((8.33lb/gal)(T2-T1))

proper mathematical syntax such as... (48/2)(9+3)??

 

[TramFan3]

proper mathematical syntax such as... (48/2)(9+3)??

(48/2)(9+3) means the same thing as 48/2(9+3). Thats the beauty of only being able to doing an operation on 2 things at once.

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

I didnt read this whole thread, so im not sure if anyone has explained it this way, and im not going to read it now because im lazy. But the human brain can only do arithmetic on two numbers at a time. This is important.

So in the order of operations we all agree that parenthesis come first.

so 48/2(9+3) becomes 48/2*12

Now we have 2 operations, division and multiplication. The order of operations says work left to right.

For those who said the answer is 2, here is the falacy.

I can only do an operation on two numbers at a time.

So I would do 48/2 first. If I did 2*12 first, then I didnt work left to right, and thus violated the order of operations.

So now im left with 24*12, and i get 288.

Math is just a game with rules, if you break the rules you cant win.