Beehaw
  • Communities
  • Create Post
  • search
    Search
  • Login
  • Sign Up
cryptix ( cryptix@discuss.tchncs.de )  to Asklemmy@lemmy.ml · 3 年前

Whats your such opinion

discuss.tchncs.de

message-square
448
link
fedilink
323

Whats your such opinion

discuss.tchncs.de

cryptix ( cryptix@discuss.tchncs.de )  to Asklemmy@lemmy.ml · 3 年前
message-square
448
link
fedilink
  • Umbrias ( Umbrias@beehaw.org ) 
    link
    fedilink
    arrow-up
    4
    ·
    3 年前

    Under normal interpretations of pemdas this is simply wrong, but it’s ok. Left to right only applies very last, meaning the divisor operator must literally come after 2(4).

    This isn’t really one of the ambiguous ones but it’s fair to consider it unclear.

    • rasensprenger ( rasensprenger@feddit.de ) 
      link
      fedilink
      arrow-up
      4
      ·
      3 年前

      Pemdas puts division and multiplication on the same level, so 34/22 is 12 not 3. Implicit multiplication is also multiplication. It’s a question of convention, but by default, it’s 16.

      https://en.m.wikipedia.org/wiki/Order_of_operations

      • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
        link
        fedilink
        English
        arrow-up
        1
        ·
        3 年前

        Implicit multiplication is also multiplication

        There’s no such thing as implicit multiplication. The answer is 1.

        • rasensprenger ( rasensprenger@feddit.de ) 
          link
          fedilink
          arrow-up
          2
          ·
          3 年前

          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

          • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
            link
            fedilink
            English
            arrow-up
            1
            ·
            3 年前

            That just states that a*(b + c) = ab + ac

            No, The Distributive Law states that a(b+c)=(ab+ac), and that you must expand before you simplify.

            For some simple exanples,

            Examples by people who simply don’t remember all the rules of Maths. Did you read the answers?

            • rasensprenger ( rasensprenger@feddit.de ) 
              link
              fedilink
              arrow-up
              2
              ·
              edit-2
              3 年前

              Please learn some math before making more blatantly incorrect statements. Quoting yourself as a source is… an interesting thing to do.

              https://en.m.wikipedia.org/wiki/Distributive_property

              I did read the answers, try doing that yourself.

              • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
                link
                fedilink
                English
                arrow-up
                1
                ·
                3 年前

                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 ( rasensprenger@feddit.de ) 
                  link
                  fedilink
                  arrow-up
                  2
                  ·
                  3 年前

                  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.

                  • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
                    link
                    fedilink
                    English
                    arrow-up
                    1
                    ·
                    3 年前

                    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 ( rasensprenger@feddit.de ) 
                  link
                  fedilink
                  arrow-up
                  2
                  ·
                  3 年前

                  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?

                  • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
                    link
                    fedilink
                    English
                    arrow-up
                    1
                    ·
                    3 年前

                    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).

      • Umbrias ( Umbrias@beehaw.org ) 
        link
        fedilink
        arrow-up
        1
        ·
        3 年前

        Incorrect, pemdas puts multiplication before division.

        • Kalash ( theKalash@feddit.ch ) 
          link
          fedilink
          arrow-up
          3
          ·
          3 年前

          Incorrect, pemdas puts multiplication before division.

          Only in the literaly order of the words.

          It stands for “Parentheses, Exponents, Multiplication/Division, Addition/Subtraction”

          Notice the “/” between multiplication and division instead of a comma? That means these have the same priority.

          • Umbrias ( Umbrias@beehaw.org ) 
            link
            fedilink
            arrow-up
            1
            ·
            3 年前

            Well there’s the problem. I maintain this to be a mistake.

            • Kalash ( theKalash@feddit.ch ) 
              link
              fedilink
              arrow-up
              2
              ·
              3 年前

              Ok. You could also maintain that 1 + 1 equals 3 if you wish. Either way you are simply wrong.

              • Umbrias ( Umbrias@beehaw.org ) 
                link
                fedilink
                arrow-up
                1
                ·
                3 年前

                I don’t think you understand my position if that’s your takeaway.

                • Kalash ( theKalash@feddit.ch ) 
                  link
                  fedilink
                  arrow-up
                  2
                  ·
                  3 年前

                  Your position is that you disagree with established maths. So you’re kind of a maths-flatearther with your own theories, I get it. But for most people that just summarizes to “being wrong”.

                  • Umbrias ( Umbrias@beehaw.org ) 
                    link
                    fedilink
                    arrow-up
                    1
                    ·
                    3 年前

                    Huh? I disagree with the convention, not the underlying math. Pemdas is a design choice lol.

        • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
          link
          fedilink
          English
          arrow-up
          1
          ·
          3 年前

          And “Multiplication” refers literally to multiplication signs, of which there are none in this question.

        • dillydogg ( dillydogg@lemmy.one ) 
          link
          fedilink
          arrow-up
          1
          ·
          3 年前

          I always thought pemdas was more like P/E/MD/AS with MD and AS occurring left to right

          • Homosexual sapiens ( Strawberry@lemmy.blahaj.zone ) 
            link
            fedilink
            arrow-up
            3
            ·
            3 年前

            This is how I was taught, but also people don’t really use the ÷ symbol in algebra beyond like 6th grade

            • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
              link
              fedilink
              English
              arrow-up
              1
              ·
              3 年前

              people don’t really use the ÷ symbol in algebra beyond like 6th grade

              Yes they do, just pick up a high school Maths textbook (in a country which uses obelus rather than colon).

    • Kalash ( theKalash@feddit.ch ) 
      link
      fedilink
      arrow-up
      2
      ·
      3 年前

      Left to right only applies very last, meaning the divisor operator must literally come after 2(4).

      That is incorrect. Multiplication does NOT have presedence of division, they are equal. So it’s left to right, which means division comes first.

      • Umbrias ( Umbrias@beehaw.org ) 
        link
        fedilink
        arrow-up
        1
        ·
        3 年前

        Which brings you to a yet further ambiguous expression. I maintain that’s a poor choice.

    • 💡𝚂𝗆𝖺𝗋𝗍𝗆𝖺𝗇 𝙰𝗉𝗉𝗌📱 ( SmartmanApps@programming.dev ) 
      link
      fedilink
      English
      arrow-up
      1
      ·
      3 年前

      This isn’t really one of the ambiguous ones but it’s fair to consider it unclear.

      #MathsIsNeverAmbiguous if you follow all the rules of Maths (there’s a lot of people here who aren’t).

Asklemmy@lemmy.ml

asklemmy@lemmy.ml

Subscribe from Remote Instance

Create a post
You are not logged in. However you can subscribe from another Fediverse account, for example Lemmy or Mastodon. To do this, paste the following into the search field of your instance: !asklemmy@lemmy.ml

A loosely moderated place to ask open-ended questions

Search asklemmy 🔍

If your post meets the following criteria, it’s welcome here!

  1. Open-ended question
  2. Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
  3. Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
  4. Not ad nauseam inducing: please make sure it is a question that would be new to most members
  5. An actual topic of discussion

Looking for support?

  • !lemmy_support@lemmy.ml
  • !fediverse@lemmy.ml
  • !selfhosted@lemmy.world

Looking for a community?

  • Lemmyverse: community search
  • sub.rehab: maps old subreddits to fediverse options, marks official as such
  • !lemmy411@lemmy.ca: a community for finding communities

Icon by @Double_A@discuss.tchncs.de

Visibility: Public
globe

This community can be federated to other instances and be posted/commented in by their users.

  • 1 user / day
  • 2 users / week
  • 1.3K users / month
  • 4.29K users / 6 months
  • 1.49K local subscribers
  • 55.8K subscribers
  • 6.92K Posts
  • 153K Comments
  • Modlog
  • mods:
  • Evan ( Cloak@lemmy.ml ) 
  • mekhos ( mekhos@lemmy.ml ) 
  • tmpod ( tmpod@lemmy.pt ) 
  • OrangeSlice ( 14specks@lemmy.ml ) 
  • BE: 0.19.15
  • Modlog
  • Legal
  • Instances
  • Docs
  • Code