EPTA Simple Math Problem? - Page 74
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Marradron
Netherlands1586 Posts
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Ceril
Sweden1343 Posts
On April 09 2011 00:47 solidbebe wrote: Well it doesn't matter which train of thought you follow to either 2 or 288, this is absolutely most definitely wrong. You ALWAYS solve brackets before dividing, so you HAVE to 2 * 12 before 48/... I claim we must not intepret the 2 as representing an actual number. the 2 is part of a number. But it is not the true number you can use to mulitply your result with with. 48/2*(3+9) the multiplication sign is most definetly there but silent in its n(3+9) form. When you add the silent bracket to show that 48/2 belong togheter as a divison into an actual number c its very clear (48/2)(9+3) a/b =c a/b(12) c(12) | ||
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trainRiderJ
United States615 Posts
On April 09 2011 00:41 UdderChaos wrote: I'm doing mathematics at one of the top universities in the UK (for what its worth) and my thought is that you deal with any brackets first, so therefore the answer should be 2. So it should be done: 48÷2(9+3)= 48÷2(12)= 48÷24= 2 Thats my 2 cents anyways. You deal with what's inside the brackets first, yes. However, after the brackets have been resolved they are treated just like any other number, you don't do the operations closest to them next. The following statements are all equivalent (had to change the order of the last one to get it to show up correctly) 48÷2(9+3) 48÷2*(9+3) 48*.5*(9+3) 1 -- * 48 * (9+3) 2 When writing an equation in a forum like this one, you need to pay extra care to whether you denote something as a fraction, or just a division operation. Obviously the "division" in a fraction is handled before any other operations because it's really just one number. Otherwise, you follow the standard rule of brackets, exponents, multiplication/division, addition/subtraction. | ||
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cyst
United States9 Posts
On April 09 2011 00:44 Pufftrees wrote: LOL I feel so bad for whatever "engineer" you are. Actually bro, the M and D and A and S are on the same tier, and you do those left to right. Maybe you should try something that doesn't involve math. Actually bro, the M and D are on the same tier, both above A and S (also on the same tier). Maybe you should try again? | ||
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Pufftrees
2449 Posts
On April 09 2011 00:53 UdderChaos wrote: By the use of the word "bro" im assuming you don't do anything in the scientific line. You also completely ignored the most important part of BEMDAS which is the B as in brackets. Haha actually I do, and the B is obviously first that why I didn't say it. The "engineers" error is that he doesn't understand that M/D and then A/S are on the same tier. The B and E are obviously first, read Xza's post on "common" errors. | ||
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Jameser
Sweden951 Posts
On April 09 2011 00:55 Deadlyfish wrote: 48/2*(9+3) = 288 48/2(9+3) = 2 That is how it is in my head  I know it's wrong, but to me this is just an optical illusion or whatever, doesnt really have a lot to do with math.Where i come from we always write x*(xx) not x(xx). And we never use that division sign either (not since like 3rd grade). that is the formally correct way to use a parenthesis btw, see my post above  | ||
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gogogadgetflow
United States2583 Posts
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Pufftrees
2449 Posts
588 people hahahah. And they do math for a living (or will). Scary stuff. | ||
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VIB
Brazil3567 Posts
On April 09 2011 00:55 Deadlyfish wrote: Actually you're one of the 1% of the thread who got it right 48/2*(9+3) = 288 48/2(9+3) = 2 That is how it is in my head I know it's wrong, but to me this is just an optical illusion or whatever, doesnt really have a lot to do with math.Where i come from we always write x*(xx) not x(xx). And we never use that division sign either (not since like 3rd grade). So you are just tricking people by writing something that they aren't used to seeing, if it was written "correctly" 99% of everyone here would get it right. | ||
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Nysze
United States111 Posts
Google Implied Multiplication, there are many many references that state that 2x is another way of writing 2 * x or 2(3) is another way of writing 2 * 3, another way of writing means that the order of operations laws still apply. Thus 48÷2(9+3) is the same as 48÷2 * (9+3). And order of operations (PEMDAS or BEMDAS, states that multiplication and division have the same priority and are to be solved left to right (source: http://en.wikipedia.org/wiki/Order_of_operations). Also how do more than half get the first problem right, then the second problem 1/2x wrong, this again is implied multiplication and equals 1 / 2 * x which is equal to x / 2. | ||
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Pigsquirrel
United States615 Posts
Step 1: Parenthesis 48/2(12) Step 2: Leftmost multiplication or division (in this case division) 24(12) Step 3: Next leftmost multiplication or division (in this case, multiplication) 288 fin. Using reciprocals + Show Spoiler + Rewritten equation: 48*.5(9+3) Step 1: Parenthesis 48*.5(12) Step 2: Leftmost multiplication 24(12) Step 3: Next leftmost multiplication 288 Order of Operations for Dummies + Show Spoiler + The standard order of operations, or precedence, is expressed in the following chart. terms inside brackets exponents and roots multiplication and division addition and subtraction A common shorthand is P. E. M. D. A. S. which is an a abbreviation of "Please excuse my dear aunt Sally" or parenthesis, exponent, mutiplication & division, addition & subtraction. This means that if a number or other symbol, or an expression grouped by one or more symbols of grouping, is preceded by one operator and followed by another, the operator higher on the list should be applied first. The commutative and associative laws of addition and multiplication allow the operators +, −, *, and / to be applied in any order that obeys this rule. The root symbol, √, requires either parentheses around the radicand or a bar (called vinculum) over the radicand. Stacked exponents are applied from the top down. It is helpful to treat division as multiplication by the reciprocal (multiplicative inverse) and subtraction as addition of the opposite (additive inverse). Thus 3/4 = 3 ÷ 4 = 3 • ¼ and 3 − 4 = 3 + (−4), that is, the sum of positive three and negative four. Symbols of grouping can be used to override the usual order of operations. Grouped symbols can be treated as a single expression. Symbols of grouping can be removed using the associative and distributive laws. http://en.wikipedia.org/wiki/Order_of_operation Anybody who got 2 misread the equation as this: ![[image loading]](http://imgur.com/fgWb7.png) | ||
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Jameser
Sweden951 Posts
On April 09 2011 01:01 Nysze wrote: It's 288, I can see how someone looking at this could think 2 at first, but I cannot understand how there can then be 73 pages with people arguing that in fact it is 2 after reading the simple explanation. Google Implied Multiplication, there are many many references that state that 2x is another way of writing 2 * x or 2(3) is another way of writing 2 * 3, another way of writing means that the order of operations laws still apply. Thus 48÷2(9+3) is the same as 48÷2 * (9+3). And order of operations (PEMDAS or BEMDAS, states that multiplication and division have the same priority and are to be solved left to right (source: http://en.wikipedia.org/wiki/Order_of_operations). Also how do more than half get the first problem right, then the second problem 1/2x wrong, this again is implied multiplication and equals 1 / 2 * x which is equal to x / 2. they get it wrong because they read the numbers in their head and following standard blackboard language "one over two x" means 1/(2x) and not ½x again, if you are used to learning your math via the internet you probably get this right, but the majority of people go to an actual school where you have intonation & blackboard to write on | ||
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SKYFISH_
Bulgaria990 Posts
On April 09 2011 00:53 Jameser wrote: the way it is written you can interpret it either way No you can't, there is only one correct way to interpret it. The division sign shows exactly which part of the equation is on top of the division line and which is under it. 48 ------ 2(9+3) from this point you can simplify it and be a total idiot about it 24 ---- 9+3 => 24 ---- 3(3+1) => 8 -- 3+1 => 8 --- 4 fifth grade guise, seriously User was temp banned for this post. | ||
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Robinsa
Japan1333 Posts
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MasterOfChaos
Germany2896 Posts
On April 09 2011 00:36 dogmeatstew wrote: The implied multiplication of n(x+y) style expressions doesn't go over well with compilers its true but adding in the '*' operator is legitimate and doesn't actually change the problem obviously. You missed the entire point of the problem. The argument is if there is a difference between * and implicit multiplication with an omitted multiplication sign. | ||
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RBKeys
Canada196 Posts
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Hesmyrr
Canada5776 Posts
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Lowell
Germany346 Posts
On April 09 2011 01:04 SKYFISH_ wrote: No you can't, there is only one correct way to interpret it. The division sign shows exactly which part of the equation is on top of the division line and which is under it. 48 ------ 2(9+3) from this point you can simplify it and be a total idiot about it 24 ---- 9+3 => 24 ---- 3(3+1) => 8 -- 3+1 => 8 --- 4 fifth grade guise, seriously Well youre wrong. You would be right if twas 48/(2(9+3) which would be the way you described it, but its 48 ----- * (9+3) = 288 2 | ||
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Brotkrumen
Germany193 Posts
On April 09 2011 01:05 MasterOfChaos wrote: You missed the entire point of the problem. The argument is if there is a difference between * and implicit multiplication with an omitted multiplication sign. Short answer: no. Long answer: I'm looking at my "mathematics for economists" and it say, no. 2x basically is 2*x for lazy people. | ||
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cyst
United States9 Posts
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