| hoozer |
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288. End of thread. http://m.wolframalpha.com/input/?i=48%C3%B72%289%2B3%29&x=0&y=0 |
| MathGuy |
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Above is correct. Multiplication does not come before division - it is whatever comes first left to right. Since there are no parenthesis, we have to divide first, 48/2 which is 24, then multiply by 12...which is 288. |
| MATHLETE |
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Actually: 48/2 is 24 24 * 9 = 216 24 * 3 = 72 216 + 72 = 288 There, I did the parentheses last and still got 288. PEMDAS or not, the answer is 288 |
| jeez |
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No, he hasn't. There is nothing about omitting the multiplication sign that imposes "implied" parentheses. 2(9+3) is always 2 * (9+3) Period. Always. If parentheses are intended they must be placed. |
| jeez |
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Actually, no they don't. |
| mplatt |
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48÷2X=288 Solve it. |
| lllll |
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Ok. I have a TI-89, which can solve equations. I entered what you wrote: solve(48/2x=288,x) the answer was 12, or (9+3). If you want that equation to group the 2x together, you need to write 48/(2x)=288. |
| jeez |
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X = 12. This has been made abundantly clear. 48 divided by 2, THEN multiplied by X equals 288. X must therefore equal 12. The "then" is important. Left to right. No matter how many times you try to pretend otherwise, "2X" still means "2 * X" Always. If you want parentheses, you must add them. |
| googogogogogogogog |
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Multiplication and division are interchangeable in PEMDAS. It becomes 48/2*12 after the parenthesis. Then it just goes left to right. 24*12.[/quote] If they are interchangeable why can't I say 2*12 and then 42/24? What is the rule that says on needs to divide 48 by 2, rather than multiply 2 by 12 first? Thanks. |
| Holy Fing Cow |
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Left to Right. Was that really so difficult? |
| googogogogogogogog |
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So are we all agreed - left to right is an unbendable math rule and is the answer to our problems on this thread? |
| Math Guy #288 |
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I don't agree that the answer is 288. When you have an equation like this you should write the question out properly. A division sign is the same thing as a fraction line. Anything under the fraction line needs to be solved first. 48÷2(9+3)should be written as: =48 ------ 2(9+3) =48 ----- 2(12) =48 ---- 24 = 2 Hopefully this comes out looking when I hit post. |
| Math Guy #288 |
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PS: The argument that since I put the equation into excel or my calculator and got 288 and there that is the correct answer is absolute nonsense. Calculators/excel do not understand the rules of mathematics. When entering something like this into a calculator/excel, you must introduce some extra brackets to help the calculator understand the way the equation was written. Otherwise it will just solve left to right which is not always correct: 48÷[2(9+3)]= |
| the real reason |
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I have a friend who does QA for TI. I assure you he is much MUCH smarter than you and has tested these things in ways you couldn't imagine. To say that some of the smartest developers in the world are wrong because of some made up rule you just said is just retarded. And by the way, you only treat it as a fraction when there are parenthesis. In your mind, 2/2*2*2 would equal 1/4, when really it is 4. You can't argue against that. If you do...well...I'll leave it to the other posters to decide what you are. |
| Math Guy #288 |
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Also, because the 2 is directly next to the (9+3) this indicates that it must be solved first. So you must do the 9+3=12 and then multiply by 2. Or you do (2x9)+(2x3)=24 (this is known as the distributive property of multiplication). Either way it's 48÷24=2. |
| webby |
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I'd like to add my voice to the chorus of people dumbstruck by the number of people who don't understand why the answer is 288. It's amazing that we can get people to compute the number of balls that fit in a sphere with deadly accuracy, but on the same board there are seemingly dozens of people who can't do basic arithmetic. |
| Math Guy #288 |
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You are correct, the answer to this question is 4. The reason for this is the addition of the x signs in the question which clearly separate the parts of the question. However the answer to the original question is still 2, for the reasons I listed above. It's quite clear you don't understand what is going so if your friend would like to come on here and debate we could have a sensible debate but you have no place. Go back to the Rupp bashing thread. |
| Math Guy #288 |
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You must do the 2(9+3) first. The 2 is a part of the brackets, you can't just ignore it and separate it out. This becomes 2x9+2x3=24. 48/24 is 2. Would you like some further help? |
| Distributive property! |
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You must do the 2(9+3) first. The 2 is a part of the brackets, you can't just ignore it and separate it out. This becomes 2x9+2x3=24. 48/24 is 2. Would you like some further help?[/quote] Damn straight Math Guy!! |
| rekrunner |
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The 2 is outside the brackets. In fact "48÷2" is outside the brackets, and therefore outside the scope of its influence, in spite of the direct contact of the 2 with the parenthesis. There is no direct contact rule. Associativity, commutativity, distributivity, and whatever other rules or properties you might think of, do not alter the rules of precedence. You can not ignore the preceding terms. Once you perform the calculation inside the brackets, there are no more brackets, and therefore nothing forces the 2 to be resolved with the new non-bracketed expression prematurely. The 2 is connected by multiplication after, and division before. You can not ignore either, but must follow a centuries old convention that binds all mathematicians above the age of 10, worth their salt, to evaluate such infixed expressions from left to right: Special note: Unary operators, e.g. negative signs, factorials, form part of the number, and must be treated as an integrated number. 48÷2(9+3)=? Step 1: Perform all groupings, e.g. brackets, parentheses, roots, from left to right 48÷2*12=? Step 2: Perform all powers (exponents), from left to right (with stacked powers top down) 48÷2*12=? Step 3: Perform all multiplication and division from left to right Step 3.1: 24*12=? Step 3.2: 288=? Step 4: Perform all addition subtraction from left to right 288=? Would you like some further help? The potential problems arising from any "ambiguity" issue was discovered by mathematicians centuries ago, if not longer, and the orders of precedence were agreed by universal convention, and defined by the precedence rule, at the time of creation of the symbolic infix notation for equations. These rules are very precise, leading to only one single interpretation of every equation that gives predictable and repeatable results every time. Mathematics could not have progressed with this kind of basic ambiguity. Parentheses are not required when it just makes explicit, that which is implicit by universal convention, although it can aid in human understanding.
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