Comment on SBA #119 maths

remon@ani.social ⁨1⁩ ⁨month⁩ ago

• agent_nycto@lemmy.world ⁨1⁩ ⁨month⁩ ago

  It is one though, you gotta do multiplication first

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  • LORDSMEGMA@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

    No. After you do the parentheses, multiplication and division are done left to right.

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    • StarvingMartist@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

      Yeah, gonna need to see a proof before I trust ANYONE on lemmy

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      • dalekcaan@feddit.nl ⁨1⁩ ⁨month⁩ ago

        en.wikipedia.org/wiki/Order_of_operations

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      • LostCarcosan@lemmy.today ⁨1⁩ ⁨month⁩ ago

        Multiplication/division and addition/subtraction both happen left to right. They… Didn’t teach you that in school?

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      • LORDSMEGMA@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

        Multiplication and division are the same operation

        6 * (1 / 2) = 6 / 2

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  • ChairmanMeow@programming.dev ⁨1⁩ ⁨month⁩ ago

    It can be both depending on how you handle operator precendence.

    PEMDAS definitely doesn’t result in 1, but in 9, since under PEMDAS multiplication and division have the same priority (and thus should resolve left-to-right). So, you should resolve to 9 (6/2(2+1) => 6/2(3) => 6/23 => 33 => 9).

    However, there’s also PEJMDAS, which suggests that implied multiplication has an operator precedence greater than regular multiplication/division (J for Juxtaposition). This version says you should do 6/2(2+1) => 6/(22 + 21) => 6/(4+2) => 6/6 => 1.

    The issue is that there is no universal agreement on which is correct. Most textbooks don’t even use the / operator, but instead rely on writing out the full fraction like ⁶⁄₂₍₂₊₁₎ or ⁶⁄₂(2+1). This removes any ambiguity there might be, and thus they don’t touch on which one is actually correct.

    Most (but not all) calculators these days will treat implied multiplication the same as regular multiplication, so you get 9 in the given example. Most programming languages do the same, or outright disallow implied multiplication because it only confuses people. Academics won’t ever use the ambiguous notation and will make sure to remove any ambiguity by either adding parentheses or using a notation like ⁶⁄₂₍₂₊₁₎, which makes things much more clear.

    Neither 9 nor 1 is wrong, the question is just stupid.

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    • db2@lemmy.world ⁨1⁩ ⁨month⁩ ago

      Now do 2+2=5

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  • remon@ani.social ⁨1⁩ ⁨month⁩ ago

    No you don’t, decision is on the left, so it comes first

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  • probablymissing@lemmy.world ⁨1⁩ ⁨month⁩ ago

    there’s no way you’re serious Image

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    • agent_nycto@lemmy.world ⁨1⁩ ⁨month⁩ ago

      :y

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      • EmpathicVagrant@lemmy.world ⁨1⁩ ⁨month⁩ ago

        P/E/M(&)D/A(&)S

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  • Atomic@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

    [deleted]

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    • remon@ani.social ⁨1⁩ ⁨month⁩ ago

      The precedence goes like this:

      parentheses > exponents > (multiplication = division) > (addition = substraction)

      If you encounter operators with the same precedence (like multiplication and division) you go by the order they appear in the equation, left to right.

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      • Atomic@sh.itjust.works ⁨1⁩ ⁨month⁩ ago

        Yes. I am well aware. 6 ÷ 2 * (2+1) = (2+1) * 6 ÷ 2 = (6 * (2+1))÷2 = 6 * (2+1) ÷ 2

        What he wanted to do is 6 ÷ (2 * (2+1))

        But this just comes down to if you treat 2(2+1) as one or two expressions.

        And honestly, i don’t blame anyone for thinking one way or the other. Because i think most people understand that we wanted to write (2(2+1)), just that the overall parentheses is implied

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• KC_Royalz@lemmy.world ⁨1⁩ ⁨month⁩ ago

  I hate math, my teacher taught is as first in last out and to this day I still get confused. The answer is 9 right?

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  • remon@ani.social ⁨1⁩ ⁨month⁩ ago

    Yes, at least by the most common agreed on convention. Almost any mathematician, programming language, search engine or spreadsheet software will say it’s 9. It is for all intents and purposes the right answer.

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    • carmo55@lemmy.zip ⁨1⁩ ⁨month⁩ ago

      There is no right answer. It just depends on convention. It’s like color vs colour, neither has been shouted down from the heavens to be the only way to write something, it depends on culture.

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      • remon@ani.social ⁨1⁩ ⁨month⁩ ago

        There very much is an agreed on convention, some people are just not using it and that is entirely their problem.

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