this post was submitted on 03 Dec 2023
418 points (100.0% liked)
196
16482 readers
2326 users here now
Be sure to follow the rule before you head out.
Rule: You must post before you leave.
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
No, you demonstrably didn't understand mine, which is, what you are saying is impossible, but you're still saying it's possible.
No, you can't. You already tried to do addition first in 2+3x4 and found out why it doesn't work. Ever since then you've been ignoring that result and pretending that there's some other way to make it work. No, there isn't. As long as multiplication is defined in terms of addition (i.e. 3x4=3+3+3+3) then it's impossible to get a right answer unless you do multiplication before addition.
No, you can't. Again, you already proved you can't.
Go ahead - I'm not holding my breath. I already told you why it literally can't work. But note that adding brackets isn't changing the order of operations - brackets are already part of the order of operations. Writing 2+3x4 as 2+(3x4) is exactly the same thing.
BTW just to FURTHER prove your "addition first" doesn't work, look at this example...
3x4+2=3x6=18. But earlier you did 2+3x4=5x4=20 - not even the same answer in an "addition first" world! Welcome to why it's impossible to make addition-first work. But knock yourself out - you're welcome to try! 😂
No, it isn't. It's part of the rules of Maths. Notation is how you write it - underlying that is how Maths actually works. This is embodied in the rules of Maths.
Completely fixed, and a result of the way the operators are defined - that was the only "arbitrary" bit, deciding what the operators were and what they were going to mean, but once you did that then the order of operations rules were already written for you (having already been determined as soon as you made the definitions of the operators in the first place).
Again, not a convention, a rule of how to interpret it. You can't just decide to interpret 5 as four, or again, you end up with wrong answers. The rules of Maths prevent you from getting wrong answers. You found that out yourself when you tried to do addition first in 2+3x4.
It's only a wrong answer if you use the same expression you would with the standard order of operations. And I'm not saying we can randomly start interpreting 5 as four, just that there is no law of the universe that makes 5 look like that, and we could theoretically (not practically ofc) switch the definitions of the symbols 5 and 4 if we did it all at once and revised old math expressions to match the new standard. Just as there is no reason the letters "bike" mean what they do other than that's what someone decided to call it, there is no reason the order of operations is what it is other than that is how someone decided to write it.
Scratch doesn't even have an order of operations. You can still do math in it.
I'm not saying you can take any expression and get the same answer by doing addition before multiplication. I'm saying you can take any problem and get the correct answer by doing addition before multiplication. In your milk example, that means I would use the expression 2+(3x4) because 2+3x4 is no longer the correct expression needed to solve the problem.
(For an example of my distinction of the words "expression" and "problem", "(4x)+2" is an expression, and "I start with 2 litres of milk. For every dollar I spend, I get 4 more liters of milk. How much milk do I have?" is a problem.)
My argument also relies on a distinction between the language of modern math and the concept of doing math, defining math as the dictionary definition of "The study of the measurement, properties, and relationships of quantities and sets, using numbers and symbols". As you can see, this makes no mention of the notation commonly used in math. All I am saying is that you can still use numbers to solve problems with an altered order of operations, or by altering any part of the system of notation.
Perhaps seeing how I could solve a problem with a different order of operations will help illustrate my argument:
Problem: 2 cars approach an interchange at a 90 degree angle to each other. Car A approaches the station from 15 meters away at 30 meters/second and Car B approaches the station from 50 meters away at 20 meters/second. How fast is the distance between the cars decreasing?
Answer: the rate of change of the distance between the cars is approximately -27.777 meters per second.
As you can see, I used my altered math notation to find the correct answer. I can still solve a real-world problem with this notation, but the same expressions you would use before may not work now.
Really? You want to do that again? Ok, fine... If I have 1 2 litre bottle of milk, and 4 3 litre bottles of milk - i.e. 2+3x4 - how many litres of milk do I have?
The definition of 5 as being 1+1+1+1+1 has nothing to do with order of operations.
No, but there is a rule of Maths which defines it.
In other words everything would be the same as now but we just switched the notation around. I already said that to you a while back. Now you're getting it.
Got nothing to do with how it's written - Maths is written differently in many different countries, and yet the underlying order of operations rules are universal.
And if it's not the same answer then it's wrong. You're nearly had it.
And I told you you can't. Waiting on a proof from you. Start with 2+3x4 - show me how you can get the correct answer by doing addition first - it's a nice simple one. :-)
They're literally the same thing.
And I told you that it's impossible. Changing the notation doesn't change the Maths.
BWAHAHAHAHA! Nope! I see you putting brackets around the multiplication to make sure it gets done first - same as if you hadn't used brackets at all! It's the exact same notation we use now, just with some redundant brackets added to it! And, predictably, you left the addition for last.
Ok, let's take your example and do addition first (like you claimed can be done)...
15²+50²=15x15+50x50=15x65x50=48,750. But 15²+50² is 2,725 according to my calculator. Ooooh, different answers - I wonder which one is right... I wonder which one is right...???
Thanks for proving it can only be done by following the order of operations rules (just like I've been saying to you all along). Bye now.
I"m beginning to wonder if you are willfully misunderstanding my point. Or perhaps you have sunk so much time into this argument you assume I must be wrong. Take another look at my third and fifth paragraphs. I promise, I am not trying to say what you think I'm trying to say.
All I did was use the expression necessary to evaluate correctly with the altered order of operations. There are, in fact, times when you can remove brackets that you would otherwise need, for example (x+4)(x-2) would no longer need brackets. The fact that "old" expressions often have to be written with new brackets to evaluate correctly with an altered order of operations is something I fully understand. The presence of brackets where there would be none otherwise does not invalidate my point.
What? I never wrote 15²+50². That is an expression you copied incorrectly. Your incorrectly copied expression has little relevance to the problem at hand.
If we were doing math with an altered order of operations, the expression 2+3x4 is just simply wrong. 2+(3x4) is the expression you need. If you try to do math the same as it is with the regular order of operations, it will not work. But that does not mean math with an altered order of operations is useless. It is still math. It can still be used to "study of the measurement, properties, and relationships of quantities and sets using numbers and symbols".
I fully understand that to correctly evaluate an expression written with a certain order of operations in mind, you need to use that order of operations. If someone wrote an expression with a different order of operations in mind, you could solve it with a different order of operations and still get what the author of the expression intended. For example, I write the equation a+2xa-2 with my order of operations, expecting you to use the same order of operations, and tell you to simplify. If you get 3a-2, that is wrong, because you used an order of operations different than the one I intended to be used to solve the problem. Imagine, for a moment, an alternate universe where everyone uses a different order of operations and a+2xa-2 simplifies to a^2-4. All I am trying to say is that that their math, with a different order of operations, would be no less useful then our math.
In summary, my only claim is that you can still use a different order of operations to manipulate numbers and solve real world problems.
I wrote and evaluated all of those expressions in my last comment with a different order of operations in mind, and was still able to come to the correct answer.
I wasn't going to reply any more, but I see now you don't understand terms either, so one more time for old time's sake (and maybe you might finally get it)...
You know teachers don't get paid for helping students outside class time right?
No assumption needed. What you are proposing is literally impossible. I've been saying that all along.
Ok...
And so far you haven't been able to show it works for any expression at all! Not even one expression! Just like I said would happen.
And I said you can't, and you haven't! All you did was put brackets around the multiplication to make sure we were still following the only order of operations that works! You have still not shown an actual instance where one can actually do addition first and get a right answer, not one! The idea that one could use addition first as an "alternate order of operations" is thus pure fantasy, just like I've been saying all along. It's literally impossible.
Yes it would! (x+4) is one term - that's what the brackets means - "these things are all together". If you remove that, because "addition first", it's now two terms, so the whole expression is two terms (instead of one), x, and 4(x-2) (which is a mistake people make when they write 8/2(2+2) as 8/2x(2+2) - just turned 2 terms into 3 terms and changed the answer!). Every example you've done so far you've used brackets to escape from having to do addition first, and the very same thing would therefore apply here - no brackets, no escaping "addition first" approach, brackets before addition leads to x+4(x-2)=x+(4x-8) =5x-8, which is not the product of (x+4) and (x-2).
No, the fact that you've not been able to show a single instance of where addition before multiplication would work does. You can't show "a way to solve this in an addition first world" when it's literally impossible for an "addition first world" to exist in the first place.
...and I removed the brackets to show that addition first doesn't work (since you keep putting in brackets to revert "addition first" back to the only order of operations that actually works).
And you've still not shown how. Every example you've used so far you've put in brackets to your (supposed) "addition first" so that we were evaluating it using the only order of operations that works. In other words, no, you can't use "addition first" to “study of the measurement, properties, and relationships of quantities and sets using numbers and symbols” - you used the regular order of operations to do it! You haven't shown a single example of where addition first could be used to do it.
You need to use an order of operations that gives a correct answer, of which there is only one - a fact you keep trying to avoid.
No it wouldn't, cos now you're ignoring terms as well. As per my earlier working out, it would simplify to 5x-8 unless you also changed the definition of terms. Do you see yet why it's impossible to have an "alternate order of operations"?
And you've completely failed to show a single instance where this is true - which is what I've been saying all along, it's impossible to have another set of order of operations that works. You keep pre-supposing it's possible, but then add brackets to the multiplications so that we follow the actual correct order of operations, the only order of operations that works.
And you've still failed to solve a single problem using addition first, because it's still a fact it's literally impossible to do so.
by using the only order of operations that works. i.e. multiplication before addition.
Now I really am done - I'm not going any further down this rabbit hole of whatever other Maths you may not understand either (this post it was Terms - who knows what's next)...