RealFunnyFungi 1 Posted April 26, 2011 Want to ask a moronic question, can anyone answer me!! 48÷2y =24y or 24/y? Share this post Link to post Share on other sites

Spyman 392 Posted April 26, 2011 Place the equation this way and it will be easier to see: [math]\frac{48}{2y}=\frac{24}{y}[/math] Share this post Link to post Share on other sites

RealFunnyFungi 1 Posted April 26, 2011 So that means i need to treat 2y as 1 term? Share this post Link to post Share on other sites

timo 539 Posted April 26, 2011 (edited) I'm afraid no one can answer that for you, except the person who gave you the ambiguous term. I would interpret it the way Spyman did (as [math] \frac{48}{2y}[/math]), but that's just from my taste of aesthetics, not because I'd know some rule that this surely cannot mean [math]\frac{48}{2}y[/math]. Edited April 26, 2011 by timo Share this post Link to post Share on other sites

Spyman 392 Posted April 26, 2011 So that means i need to treat 2y as 1 term? Otherwise it should have been: (48/2)y = 24y Share this post Link to post Share on other sites

timo 539 Posted April 26, 2011 (edited) Do you know that or do you just assume that because it is intuitive, Spyman? Edited April 26, 2011 by timo Share this post Link to post Share on other sites

RealFunnyFungi 1 Posted April 26, 2011 Well...Thx for ur help I've also got a question which i guess almost everyone knows lol is that 48÷2(9+3) = ? Share this post Link to post Share on other sites

Spyman 392 Posted April 26, 2011 (edited) Do you know that or do you just assume that because it is intuitive, Spyman? Assume, I am no math expert and don't know any rule for this either. I guess for this cind of question the math is of such level that multiplication of 2 and y should have precedence. 48÷2(9+3) = ? Well, I don't think the answer is 24×12, do you? [EDIT] Actually I think the general rules are to first perform any calculations inside parentheses and then multiplications/divisions take precedence before additions/subractions and priority is from left to right. However 48/2(9+3) is different than 48/2×(9+3) since the multiplication sign is significantly missing in the first equation. When it is removed I always intuitive put an extra parentheses around that part making it 48/(2×(9+3)) or 48/(2×y). Edited April 26, 2011 by Spyman Share this post Link to post Share on other sites

RealFunnyFungi 1 Posted April 26, 2011 well I guess it should be 2 at first but later i asked my classmates and they had different answers Some are 2 and some are 288 That's why i am confused Share this post Link to post Share on other sites

Xittenn 176 Posted April 26, 2011 I usually take 2(9+3) to mean (2(9+3)) and not 2 * (9+3) so I think that 48÷2(9+3) is asking for 48÷(2(9+3)) and the answer is 2. This is also the more logical answer given the context and the numbers. I think in general, oversights like this are avoided at all costs in literature and they generally constitute a mistake. It is usually pretty clear the intention and this isn't something you should dwell on; there are better uses for your time. lol Share this post Link to post Share on other sites

ewmon 158 Posted April 26, 2011 (edited) So that means i need to treat 2y as 1 term? Just ask yourself: Why would you divide 48 by the 2 but not by the y? If you had $48 billion, and you had to divide it among 2 hundred people, or 2 thousand people, or 2 million people, you would divide the $48 billion by the 2 *and* the hundred, or thousand, or million. Edited April 26, 2011 by ewmon Share this post Link to post Share on other sites

RealFunnyFungi 1 Posted April 27, 2011 I usually take 2(9+3) to mean (2(9+3)) and not 2 * (9+3) so I think that 48÷2(9+3) is asking for 48÷(2(9+3)) and the answer is 2. This is also the more logical answer given the context and the numbers. I think in general, oversights like this are avoided at all costs in literature and they generally constitute a mistake. It is usually pretty clear the intention and this isn't something you should dwell on; there are better uses for your time. lol How can you prove that 2(9+3) = (2(9+3))? I mean the bracket( 2(9+3) ) is added yourself. My primary teacher told me that brackets are at the first priority to solve and there is no rule of precedence of multiplication and division. That means after solving the brackets, we have 48 ÷ 2(9+3) =48 ÷ 2 x 12 =288 and that's also quite reasonable , i guess. Well but my first answer is 2. Truely , i thought it is 2 but the ''288 guys'' still have their own reasons which can't be neglected. Share this post Link to post Share on other sites

Xittenn 176 Posted April 27, 2011 (edited) It's not an issue of proof, this is not conventional mathematics and this is why this is ambiguous. It's an accepted way of doing things just as 2x really means 2 * x, it is an ugly thing to do but it happens. It is what is called 'implied' . . . . . . . . . . . . . If you wish to maintain conventional mathematics than indeed the answer is 288, but I can guarantee you 100% that this was not the intention. There are a number of other ways that this could have been written that are, statistically speaking, far more likely to have been used. Given the statistics if you answer 288, well you would be someone who ignores their own better judgment; I mean you are questioning this! Edited April 27, 2011 by Xittenn Share this post Link to post Share on other sites

CaptainPanic 1153 Posted April 27, 2011 So that means i need to treat 2y as 1 term? Yes. Just like you can treat "2 eggs" as one term, or "two bananas", "two dollars", or "two hours". You don't just have "two". You have to specify "two what?". Share this post Link to post Share on other sites

Spyman 392 Posted April 27, 2011 well I guess it should be 2 at first but later i asked my classmates and they had different answers Some are 2 and some are 288 That's why i am confused Was not this a test you have finished and as of which you now could ask your teacher for the intention and answer of the question? Or are you trolling and trying to stirr up fuzz? Share this post Link to post Share on other sites

DrRocket 333 Posted April 28, 2011 (edited) well I guess it should be 2 at first but later i asked my classmates and they had different answers Some are 2 and some are 288 That's why i am confused The general rule in mathematics is to be clear. "48÷2(9+3)" is not clear. To make it clear one needs to use parentheses. So one would write either 48÷(2(9+3) or (48÷2)(9+3). There is no point in arguing over what 48÷2(9+3) is "supposed to mean" as that reqiuires divining the intent of the writer. The fundamental problem is the symbol "÷" which is not normally used in scientific circles, or polite company, anyway. I have not seen it in regular use since about the third grade (caculators using algebraic notation (ugh!) excepted). I have been a professional mathematician for over three decades. I understand arithmetic pretty well, but I flunk tests of clairvoyance with regularity. When in doubt ask the author. Edited April 28, 2011 by DrRocket Share this post Link to post Share on other sites

kavlas 7 Posted May 11, 2011 Want to ask a moronic question, can anyone answer me!! 48÷2y =24y or 24/y? nouseforaname do you know that you can actually prove that 48÷2y= 24/y and not 24y?? Share this post Link to post Share on other sites

Bignose 941 Posted May 11, 2011 nouseforaname do you know that you can actually prove that 48÷2y= 24/y and not 24y?? no, you can't. you can't "prove" (no matter how big a font you use) a convention. You decide on a convention, and stick to it. The question as asked depends on what convention one uses. Share this post Link to post Share on other sites

kavlas 7 Posted May 11, 2011 no, you can't. you can't "prove" (no matter how big a font you use) a convention. You decide on a convention, and stick to it. The question as asked depends on what convention one uses. Well . Do we not define division in rational and in real Nos a÷b = [math]\frac{a}{b}= a\frac{1}{b}[/math]?? Share this post Link to post Share on other sites

Bignose 941 Posted May 11, 2011 Well . Do we not define division in rational and in real Nos a÷b = [math]\frac{a}{b}= a\frac{1}{b}[/math]?? How does this "prove" whether the y in the OP's question is in the numerator or denominator? Share this post Link to post Share on other sites

kavlas 7 Posted May 12, 2011 How does this "prove" whether the y in the OP's question is in the numerator or denominator? well ,the proof is high school level and it is the following: [math]\frac{48}{2y} = 48.\frac{1}{2y}[/math]=...........................................by using the definition of division: [math]\frac{a}{b}= a\frac{1}{b}[/math] =[math]48(\frac{1}{2}\frac{1}{y})[/math]=..................................................by using the theorem :[math]\frac{1}{a}\frac{1}{b}=\frac{1}{ab}[/math] and the axiom : 1a =a =[math](48.\frac{1}{2})\frac{1}{y}[/math]=...................................................by using the axiom : (ab)c =a(bc) =[math][(24.2)\frac{1}{2}]\frac{1}{y}[/math]=..................................................by using the theorem in Natural Nos 48 =24.2 =[math][24(2\frac{1}{2})]\frac{1}{y}[/math]=....................................................by using again the axiom : (ab)c = a(bc) =[math]24\frac{1}{y}[/math]=............................................................................by using the axiom : [math]a\neq 0\Longrightarrow a\frac{1}{a}=1[/math] and also the axiom :1a = a =[math]\frac{24}{y}[/math]................................................................................by using again the definition of division Share this post Link to post Share on other sites

DJBruce 143 Posted May 12, 2011 (edited) Umm, you assumed that the OP's ambiguous statement means [math]\frac{48}{2y}[/math], and surely there is no argument that if this is the case then it does equal [math]\frac{24}{y}[/math], however, the point is that this statement is ambiguous since we are not sure whether it means [math]\frac{48}{2y}[/math] or [math](\frac{48}{2})y[/math], and that you cannot prove the convention of how we interoperate the OP's expression. Edited May 12, 2011 by DJBruce Share this post Link to post Share on other sites

kavlas 7 Posted May 12, 2011 Want to ask a moronic question, can anyone answer me!! 48÷2y =24y or 24/y? Umm, you assumed that the OP's ambiguous statement means [math]\frac{48}{2y}[/math], and surely there is no argument that if this is the case then it does equal [math]\frac{24}{y}[/math], however, the point is that this statement is ambiguous since we are not sure whether it means [math]\frac{48}{2y}[/math] or [math](\frac{48}{2})y[/math], and that you cannot prove the convention of how we interoperate the OP's expression. Well ,what did the OP asked?? Is there any mathematical book in the whole history of mathematics in which 48÷2y can be equal to [math](\frac{48}{2})y[/math]??? Share this post Link to post Share on other sites

DJBruce 143 Posted May 13, 2011 (edited) Well ,what did the OP asked?? Is there any mathematical book in the whole history of mathematics in which 48÷2y can be equal to [math](\frac{48}{2})y[/math]??? As the OP indicated by saying, "=24y or 24/y?" the he was asking how we would interoperate the expression given. As for where has 48÷2y been equal to: [math](\frac{48}{2})y[/math], according the standard oder of operations taught in children operations should be evaluated in the following order Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction (PEMDAS), and when operations of equivalent order are next to each other they are evaluated from left to right. Meaning that since division and multiplication of are same order we would evaluate 48÷2y as being (48÷2)y --since division furthest to the left. To read about the standard order of operations see: http://www.purplemath.com/modules/orderops.htm http://www.mathsisfun.com/operation-order-pemdas.html http://www.math.com/school/subject2/lessons/S2U1L2GL.html Edited May 13, 2011 by DJBruce Share this post Link to post Share on other sites

rktpro 106 Posted May 13, 2011 2y should be treated as one term because when you get a value for the variable y it is to be multiplied with two. Taking y separately would hamper the result. The co-efficient is always taken with the variable to get exact result. Share this post Link to post Share on other sites