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a very emphatic answer
(lemmy.blahaj.zone)
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this post was submitted on 26 May 2024
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Even your "BODMAS" isn't universal, lots of people learn "PEMDAS" or "BEDMAS"
At any level of mathematics after elementary school, you never see terrible expressions like this. Well, except for facebook and twitter
Take for example: 2/2*2 It is 0.5 or 2 depending on order. But if I were anything after high school (I was more complacent in high school, I guess) if someone gave me an arbitrarily solved equation or expression like this, I would be livid and raise hell at them for trying to do that.
Yes, the fundamentals the same, higher orders come first. BUT...
-Multiplication comes before division in some forms, like PEMDAS. In the example I use, this changes the answer.
-When you apply an operation, you should specify what it is operating on. In all of these acronyms, addition comes before subtraction, but with a different example:
The minus sign only applies to the middle term, by convention. It is the equivalent of "adding negative two". You can quickly see that this expression is equal to 2.
But if you use one of these acronyms, you end with this expression evaluating to -2. I would say it is almost universally accepted that 2 is the correct answer, and -2 is incorrect. Basically, all these acronyms end up being useless waste of time.
I don't know if I conveyed this the first time, but, as a lover of pure mathematics, this is something that does not have application in life or in study. It's an utterly useless waste of time. There is never a case where someone give you numbers like this, where it is not clear what order the numbers should be applied in.
If you have both multiplication and division then you do them left to right. PEMDAS doesn't mean multiplication first, nor does BEDMAS mean division first. It's PE(MD)(AS) and BE(DM)(AS) where the bracketed parts are done left to right.
Left associativity means it always operates on the following term. i.e. terms are associated with the sign on their left.
By the rule of left associativity.
No it doesn't. How on Earth did you manage to get -2?
No they're not, but I don't know yet where you're going wrong with them without seeing your working out.
You are adding more rules to protect a convention that doesn't work and doesn't mention them to begin with. If all that matters is higher orders first, then why bother having an acronym? Just say "Brackets, then higher orders". Bam. Solved it with less words than any of the acronyms.
As someone who studied mathematics, computer science, and engineering in university, I certainly don't you to tell me how to do bare bones arithmetic. I know operators apply to the numbers to their right. Everyone does. You jumped right on by the point.
With 2/2*2, you don't know if it is 2*2/2, or 2/(2*2). When you are dividing by numbers, you put them all in the denominator. If I had to put it in a line, I would at least do 2/(2)*2, to show what is in the denominator. If it is ambiguous, you have done it incorrectly.
BY CONVENTION, as I said. You don't have to repeat what I said a second time.
wow. geez. I wonder.
If you can't follow the steps guided for such a simple example, maybe we just shouldn't have this conversation. It's not like you could have tried in your head different orders to combine 3 numbers.
I'm stating the existing rules.
I don't even know what you mean by that. We have the acronyms as a reminder of the rules, as I already said.
If you know that then how did you get 2-2+2=-2?
Yes you do - left associativity. i.e. there's no brackets.
Only the first term following a division goes in the denominator - left associativity.
I didn't. You said it was a convention, and I corrected you that it's a rule.
addition first
2-2+2=4-2=2
subtraction first
2-2+2=-2+2+2=-2+4=2
left to right
2-2+2=0+2=2
3 different orders, all the same answer
The rules are universal, only the mnemonics used to remember the rules are different
... and high school Maths textbooks, and order of operations worksheet generators, and...
It's always 2. #MathsIsNeverAmbiguous
The rules and the acronyms describe different things. If you have to make more rules to say M and D are the same, and that you go left to right when you do them, then the basic rules you followed were flawed. The universal conventions of mathematics don't need these acronyms confusing people.
I haven't seen anything since early elementary school, not middle school, and certainly not high school. Regardless, if a textbook has it, it doesn't make it right at all. If the acronyms are useless to learn, having them in a textbook doesn't validate them.
...that's one of the two examples you used? Did you think about that before you typed it out?
IT IS AMBIGUOUS IN THIS POST AND ALL EXAMPLES I HAVE SHOWN. That is the problem at hand.
There is no real problem solving in trying to decipher poorly written shit. It's the equivalent if English classes took time out to give students worksheets with "foder" written on them, and expecting students to find out if the writer meant "folder" or "fodder"- no sentence context, just following a list of "rules". It is not difficult to write mathematical expressions with clear context to how numbers relate, even with the lazy shortcuts and shorthand that mathematicians love.
No, they don't.
I didn't make more rules - that's the existing rules. Here's one of many graphics on the topic which are easy to find on the internet...
Yes. Did you try looking for one and ramping it up to the most difficult level? I'm guessing not.
No, it isn't. Division before subtraction, always.
None of those have been ambiguous either, as I have pointed out.
The problem is people not obeying the rules of Maths.
It's not poorly written. It's written the exact way you'd find it in any Maths textbook.