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Tópico: 48÷2(9+3)=??? 2 or 288 |
1376 respostas
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I am not arguing anymore... just want straight answers, as I honestly trend to answer C now...
Quote ( Hans Kranz @ April 27th 2011,04:54:41 )
2) the "this is a fraction and i know how to read fractions"-party
= those who don't know that 48/2a is 24a and NOT 24/a. To get 24/a you need brackets around the 2a, means 48/(2a). And no, you can't situate them in this case. What you could do is (48)/(2)*(a), cos brackets around single numbers are allowed --but superfluous.
so... you are saying that
48/ab <> 48/ba ??
question to the people that said wolfram were the gods of maths
how can you explain this??
http://img801.imageshack.us/img801/227/sinttulo1qv.jpg
why does replacing a with 2 changes the way it reads it?
shouldn't be following the same rules?
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I guess this would never happen if this is written by hand, because you would state a position for the 9+3 either on the top or bellow the fraction.
The position of it, is what it makes it complicated.
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Quote ( Marcelo Michelini @ April 27th 2011,05:20:32 )
so... you are saying that
48/ab <> 48/ba ??
Originally i wanted to leave this thread but you are asking me directly, so:
No, i'm not saying that.
What i'm saying is that 48/(ab) would be the same as 48/(ba)
but since there are no brackets (and you can't situate them there) you can't exchange a and b cos then you get a different result.
48/ab = 48/a*b ..and that's 288 in "our" example.
If you would exchange a and b, this would be
48/ba = 48/b*a .. and that's 8 in "our" example,
so that's a different result, means: not allowed.
Quote ( Marcelo Michelini @ April 27th 2011,05:20:32 )
why does replacing a with 2 changes the way it reads it?
shouldn't be following the same rules?
Granted, that's confusing. Cos normally the wolfram-guys should "know what they are doing there".
The confusion is not the "replacing a with 2" but the incorrect reading of the "missing" multiplication sign "*".
If you type in 48/2a here http://www.algebra.com/services/rendering/simplifier.mpl you get the correct result 24a.
Hmm, no clue why wolfram is weakening in this case. A wild guess could be that it is programmed like an old TI calculator but that would be a disgraceful shame, so no, can't be. No clue.
(but thanks for showing this, Marcelo, cos that explains at least a notably part of the 42%)
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At first 48\2, then *(9+3)=288!
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#1025 Postado 27 Abr 2011, 10:03:46 (editado pela última vêz 27 Abr 2011, 10:04:48 por Elmir Karic)
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48÷2(9+3)=??? or
48/2(12)=48/24=2
This is 100 % true
ok
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Quote ( Mark Jeacock @ April 26th 2011,22:24:39 )
It can be 2 or 288. There is no rule in maths that says whether it is 48/2 then * 12 or whether it is 48/24. It needs an extra set of brackets to define what the answer should be like so:
48/(2*12) or (48/2)*12
therefore it could be either! The equation has just not been fully defined :)
This is actually ridiculous now! This quote is what I said before-this is the actual answer. It can be either as the equation has not been correctly written and is not fully defined.
I am right and I now I am, and anyone who says otherewise is wrong, very wrong. If you think its 2, then yes it could be, if you think it is 288, then yes it could be. It needs an extra set of brackets to fully define it for a definite answer.
And, if you think otherwise, then I'm sorry but your wrong! :)
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Quote ( Mark Jeacock @ April 27th 2011,12:21:32 )
I am right and I now know I am
Quote ( Mark Jeacock @ April 27th 2011,12:21:32 )
And, if you think otherwise, then I'm sorry but your you're wrong! :)
Debating maths because your English is poor? :p
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Type that exact equation into any good calculator, and you will get two as your answer. If you ask any exam board, you will get two.
If you get 288 you are mathematically challenged, and should go back to school.
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Quote ( Mark Jeacock @ April 27th 2011,12:21:32 )
Quote ( Mark Jeacock @ April 26th 2011,22:24:39 )
It can be 2 or 288. There is no rule in maths that says whether it is 48/2 then * 12 or whether it is 48/24. It needs an extra set of brackets to define what the answer should be like so:
48/(2*12) or (48/2)*12
therefore it could be either! The equation has just not been fully defined :)
This is actually ridiculous now! This quote is what I said before-this is the actual answer. It can be either as the equation has not been correctly written and is not fully defined.
I am right and I now I am, and anyone who says otherewise is wrong, very wrong. If you think its 2, then yes it could be, if you think it is 288, then yes it could be. It needs an extra set of brackets to fully define it for a definite answer.
And, if you think otherwise, then I'm sorry but your wrong! :)
I agree with this.
There are no exactly correct ways of doing this.
If you use BIDMAS (like me), then it is:
48/2(9+3)=???
with brackets first:
48/2(12)
Then division:
24(12)
Then multiplication:
24*12=488.
Division and multiplication are on the same level but that's how I did it.
The other way (which gives the other answer), Expanding brackets:
48/2(9+3)
As always Brackets is first:
48/2(12)
But this time it is:
48/2*12
=48/24
Which gives the answer 2.
So as said, there is no definite correct answer as you can get two different answers from two different methods from which BOTH are legal methods in my eyes.
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Quote ( Michael Pollard @ April 27th 2011,12:37:42 )
Type that exact equation into any good calculator, and you will get two as your answer. If you ask any exam board, you will get two.
I have two Casio scientific calculators. One gives 2, the other 288. Also a Sharp calculator gives 2.
If you add in an extra multiplication sign, they all give 288;
48/2*(9+3) = 288
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Quote ( Andrew Watson @ April 27th 2011,12:44:59 )
If you add in an extra multiplication sign, they all give 288;
48/2*(9+3) = 288
Yeap, I wouldn't disagree with that, but then you have changed the original equation..
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Quote ( Michael Pollard @ April 27th 2011,12:46:30 )
I wouldn't disagree with that, but then you have changed the original equation..
Agree.
I reckon there is a distinction between 2(9+3) and 2*(9+3)
2*(9+3) effectively means;
2 x 1(9+3)
But we don't bother writing the 1
in 2(9+3), the 2 has replaced the 1, above, and is part of the bracket function so gets solved first.
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Quote ( Kevin Parkinson @ April 27th 2011,12:33:04 )
Quote ( Mark Jeacock @ April 27th 2011,12:21:32 )
I am right and I now know I am
Quote ( Mark Jeacock @ April 27th 2011,12:21:32 )
And, if you think otherwise, then I'm sorry but your you're wrong! :)
Debating maths because your English is poor? :p
Good point well made! And I am little disappointed in myself for making those mistakes. But this is a maths debate and not an English one, so I think I can get away with it :p
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Bedmas.
First the brackets:
48/2(9+3)
48 / (2x9 + 2x3)
48 / (18 + 6)
48 / 24
2
This is the way to remove the brackets, so what's the problem?
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The answer is 2
with the last post on page 1 show why it have to be 2.
a other way:
48/2(9+3)= x
x= 24/(9+3) !!!
x= 24/12
x= 2
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Quote ( Luis Berenguer @ April 27th 2011,13:02:10 )
Bedmas.
First the brackets:
48/2(9+3)
48 / (2x9 + 2x3)
48 / (18 + 6)
48 / 24
2
This is the way to remove the brackets, so what's the problem?
Problem solved!!!
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Quote ( Christian Fandrich @ April 27th 2011,13:45:39 )
a other way:
48/2(9+3)= x
x= 24/(9+3) !!!
x= 24/12
x= 2
What is that?
48/2(9+3)= x and x= 24/(9+3) is not the same thing!
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but that thing is explicity adding the "*", while 2ers never use it
says "Simplify 48/a*(9+3):"
and I think that 90% of people would chose 288 if the "*" was written
at least I would have done it at the beggining instead of picking 2
Quote ( Hans Kranz @ April 27th 2011,07:40:37 )
Hmm, no clue why wolfram is weakening in this case. A wild guess could be that it is programmed like an old TI calculator but that would be a disgraceful shame, so no, can't be. No clue.
(but thanks for showing this, Marcelo, cos that explains at least a notably part of the 42%)
no problem :)
if they don't even agree, why should we? :p
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Первым делается действие в скобках!!!!!!!!!!затем уже по порядку деление и умножение
48/2(9+3)=288
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I think the answer is 2. It's a distributive property example. It could be write like this:
48
_______
2(9+3)
so:
48 / (2*9 + 2*3)
48 / (18 + 6)
48 / 24
2
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Quote ( Milivoj Pomper @ April 27th 2011,00:11:17 )
When you have both in same equation and no brackets to determine the order of operations you do them from left to right.
Wrong. You can do them in any order you wish, because the end result is the same.
( A * B) * C = A * ( B * C)
There's no mathematical "rule" that says "left to right". It's a convention, nothing more. People can follow it, don't have to.
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Quote ( Jan Zaluski @ April 27th 2011,21:32:38 )
( A * B) * C = A * ( B * C)
yes, but its not the same here A:B*C and A*B:C
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Quote ( Tomas Zukauskas @ April 27th 2011,21:43:09 )
yes, but its not the same here A:B*C and A*B:C
Of course it is, dividing is the same as multiplying by the reciprocal.
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really?
1:2*3=?
1:(2*3)=?
1*2:3=?
and etc etc
count :)
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#1045 Postado 27 Abr 2011, 21:53:28 (editado pela última vêz 27 Abr 2011, 21:54:01 por Jan Zaluski)
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Ambigious notation is ambigious. That's not proper mathematical notation.
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Quote ( Jan Zaluski @ April 27th 2011,21:32:38 )
Wrong. You can do them in any order you wish, because the end result is the same.
( A * B) * C = A * ( B * C)
There's no mathematical "rule" that says "left to right". It's a convention, nothing more. People can follow it, don't have to.
But when you have different operations, the result is not same anymore.
(A / B) * C =/= A / (B * C) and
(A - B) + C =/= A - (B + C)
In these cases the rule is left to right. Or are you really saying that people can mean whatever they want by 10-5+4.
There are differences in notations, but so that everyone don't need explain every time what mean by simple things like a-b+c, it is generally agreed what they mean. You can call them rules or conventions, whatever. You can of course do differently if you tell that you are going to do differently, but in some cases it is just really stupid and confusing.
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Quote ( Jukka Sireni @ April 27th 2011,21:54:57 )
In these cases the rule is left to right. Or are you really saying that people can mean whatever they want by 10-5+4.
errr...
5+4 = 10-1
of course you can :)
you can even get high and do 14-5 !
as far as I learnt, the order doesn't alter the result, unless of course you have changed the order in a wrong way...
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Quote ( Marcelo Michelini @ April 27th 2011,21:58:55 )
as far as I learnt, the order doesn't alter the result, unless of course you have changed the order in a wrong way...
Count 5+4 first and you get 10-9=1, count 10-5 first and you get 5+4=9.
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Quote ( Jukka Sireni @ April 27th 2011,22:01:23 )
Count 5+4 first and you get 10-9=1, count 10-5 first and you get 5+4=9.
no boy, it's -5+4
you can't dismiss negative numbers because you are in the mood :)
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Quote ( Marcelo Michelini @ April 27th 2011,21:58:55 )
5+4 = 10-1
yes you are right.. but its not the same with : and * :)
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