• rasensprenger@feddit.de
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    8 months ago

    I don’t know what you’re on about with your distributive law thing. That just states that a*(b + c) = a*b + a*c, and has literally no relation to notation.

    And “math is never ambiguous” is a very bold claim, and certainly doesn’t hold for mathematical notation. For some simple exanples, see here: https://math.stackexchange.com/questions/1024280/most-ambiguous-and-inconsistent-phrases-and-notations-in-maths#1024302

        • Please learn some math

          I’m a Maths teacher - how about you?

          Quoting yourself as a source

          I wasn’t. I quoted Maths textbooks, and if you read further you’ll find I also quoted historical Maths documents, as well as showed some proofs.

          I didn’t say the distributive property, I said The Distributive Law. The Distributive Law isn’t ax(b+c)=ab+ac (2 terms), it’s a(b+c)=(ab+ac) (1 term), but inaccuracies are to be expected, given that’s a wikipedia article and not a Maths textbook.

          I did read the answers, try doing that yourself

          I see people explaining how it’s not ambiguous. Other people continuing to insist it is ambiguous doesn’t mean it is.

          • rasensprenger@feddit.de
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            8 months ago

            If you read the wikipedia article, you would find it also stating the distributive law, literally in the first sentence, which is just that the distributive property holds for elemental algebra. This is something you learn in elementary school, I don’t think you’d need any qualification besides that, but be assured that I am sufficiently qualified :)

            By the way, Wikipedia is not intrinsically less accurate than maths textbooks. Wikipedia has mistakes, sure, but I’ve found enough mistakes (and had them corrected for further editions) in textbooks. Your textbooks are correct, but you are misunderstanding them. As previously mentioned, the distributive law is about an algebraic substitution, not a notational convention. Whether you write it as a(b+c) = ab + ac or as a*(b+c) = a*b + a*c is insubstantial.

            • If you read the wikipedia article

              …which isn’t a Maths textbook!

              also stating the distributive law, literally in the first sentence

              Except what it states is the Distributive property, not The Distributive Law. If I call a Koala a Koala Bear, that doesn’t mean it’s a bear - it just means I used the wrong name. And again, not a Maths textbook - whoever wrote that demonstrably doesn’t know the difference between the property and the law.

              This is something you learn in elementary school

              No it isn’t. This is a year 7 topic. In Primary School they are only given bracketed terms without a coefficient (thus don’t need to know The Distributive Law).

              be assured that I am sufficiently qualified

              No, I’m not assured of that when you’re quoting wikipedia instead of Maths textbooks, and don’t know the difference between The Distributive Property and The Distributive Law, nor know which grade this is taught to.

              Wikipedia is not intrinsically less accurate than maths textbooks

              BWAHAHAHAHA! You know how many wrong things I’ve seen in there? And I’m not even talking about Maths! Ever heard of edit wars? Whatever ends up on the page is whatever the admin believes. Wikipedia is “like an encyclopedia” in the same way that Madonna is like a virgin.

              but you are misunderstanding them

              And yet you have failed to point out how/why/where. In all of your comments here, you haven’t even addressed The Distributive Law at all.

              Whether you write it as a(b+c) = ab + ac or as a*(b+c) = ab + ac is insubstantial

              And neither of those examples is about The Distributive Law - they are both to do with The Distributive Property (and you wrote the first one wrong anyway - it’s a(b+c)=(ab+ac). Premature removal of brackets is how many people end up with the wrong answer).

              • rasensprenger@feddit.de
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                8 months ago

                Let me quote from the article:

                “In mathematics, the distributive property of binary operations is a generalization of the distributive law, which asserts that the equality x*(y+z) = x*y + x*z is always true in elementary algebra.”

                This is the first sentence of the article, which clearly states that the distributive property is a generalization of the distributive law, which is then stated.

                Make sure you can comprehend that before reading on.

                To make your misunderstanding clear: You seem to be under the impression that the distributive law and distributive property are completely different statements, where the only difference in reality is that the distributive property is a property that some fields (or other structures with a pair of operations) may have, and the distributive law is the statement that common algebraic structures like the integers and the reals adhere to the distributive property.

                I don’t know which school you went to or teach at, but this certainly is not 7th year material.

                • which clearly states that the distributive property is a generalization of the distributive law

                  Let me say again, people calling a Koala a Koala bear doesn’t mean it actually is a bear. Stop reading wikipedia and pick up a Maths textbook.

                  You seem to be under the impression that the distributive law and distributive property are completely different statements

                  It’s not an impression, it’s in Year 7 Maths textbooks.

                  this certainly is not 7th year material

                  And yet it appears in every Year 7 textbook I’ve ever seen.

                  Looks like we’re done here.

                  • rasensprenger@feddit.de
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                    8 months ago

                    If you don’t want to see why you’re wrong that’s your thing, but I tried. I can just say, try to re-read the math textbook you took pictures of, and try to understand it.

          • rasensprenger@feddit.de
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            8 months ago

            About the ambiguity: If I write f^{-1}(x), without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous. It’s correct notation in both cases, used since forever, but you need to explicitly disambiguate if you want to use it.

            I hope this helps you more than the stackexchange post?

            • If I write f^{-1}(x), without context, you have literally no way of knowing whether I am talking about a multiplicative or a functional inverse, which means that it is ambiguous

              The inverse of the function is f(x)^-1. i.e. the negative exponent applies to the whole function, not just the x (since f(x) is a single term).

              • rasensprenger@feddit.de
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                8 months ago

                You can define your notation that way if youlike to, doesn’t change the fact that commonly f^{-1}(x) is and has been used that way forever.

                If I read this somewhere, without knowing the conventions the author uses, it’s ambiguous