• the_tab_key@lemmy.world
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    3 days ago

    Even if the x-x term didn’t exist, the equation is already simplified (fully factored) so there is nothing to do anyway.

  • GreyBeard@lemmy.one
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    4 days ago

    For those of you who were confused even after reading the comments: (a)(b) basically means a*b. My mind just didn’t connect that to the fact that (x-x)=0. in the (a-x)(b-x) stuff is also (x-x) which = 0, and anything * 0 = 0, so no matter the value of literally everything else in the equation, it all equals out to 0 because every single () will get multiplied by (x-x), which is 0. There, hopefully that will clear it up for anyone remaining lost. And like all good jokes, they are always best when you have to explain them.

      • superkret@feddit.org
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        3 days ago

        To make sure what’s inside the brackets is resolved internally before they’re multiplied with each other.

         (a)  (b)   =   a * b  
        (a+1)(b+1) =/= a+1*b+1
        
        • brbposting
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          3 days ago

          TIL this notation makes it math the text up

          (a)  (b)   =   a * b  
              (a+1)(b+1) =/= a+1*b+1
          

          Edit: hmm, already shows in a code block so adding backticks didn’t do anything

      • GreyBeard@lemmy.one
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        3 days ago

        To expand on what superkret said, in math there is the concept of “order of operations”. That is to say, every function in math (add, multiply, divide) has to be done in a specific order. Since multiplication comes before addition and subtraction, if you have a formula like a-x*b-x, you will do x*b first, then a minus the result of x*b, which would give a very different result than if you did a-x and multiplied that by b-x. This is where the parenthesis come in. You are basically saying, resolve every section in parenthesis first using the proper order, then resolve the rest.

        My original example (a)(b) was over simplified, because there is no conflict there. You can also do things like (a*x)-(b*x). If there is no operator though, it is assumed multiplication, and I’m unsure why that is.

        • starman2112
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          3 days ago

          Putting multiple asterisks in a comment makes it look italicized, at least on some Lemmy clients. If you want to have asterisks with *unitalicized* text, you gotta put a \ behind the * to negate the change

      • Jyek
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        3 days ago

        Because you wrote a lot less when writing it this way. Groups of terms beside each other are multiplying each other and you have to solve what’s inside of those groups before multiplying them together.

  • LostXOR@fedia.io
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    3 days ago

    Fun fact, omitting the (x-x) zero term and expanding the entire polynomial, you’d get something with 2^25 = 33,554,432 terms. May be slightly excessive!

    • threelonmusketeers
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      3 days ago

      Couldn’t you combine a lot of like terms as you went along, though? A polynomial of the order x26 would only have 27 terms.

        • threelonmusketeers
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          2 days ago

          Huh, I’m so used to polynomials being in the form ax^2 + bx + c that I never considered that every letter might be a variable.

  • Saganaki@lemmy.one
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    4 days ago

    For those that struggled like me…

    Going from a-z, write out the last three multiplicands.

      • copd@lemmy.world
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        3 days ago

        Technically there is a (x - 𝑥) in there. U+1D465 != x so this post is a little meh

        • pyre@lemmy.world
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          2 days ago

          the first variables aren’t roman. they’re italicized as well. idk where you’re getting the x vs x thing.

        • MBM@lemmings.world
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          3 days ago

          Mathematicians do weird stuff to get more letters, but I’ve never seen anyone use x and 𝑥 for different things

          • threelonmusketeers
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            2 days ago

            I’ve never seen anyone use x and 𝑥 for different things

            Yeah, me neither. I have had situations where I needed to distinguish between u, v, nu, and upsilon though. I had to be very careful with my handwriting that day…

          • joshthewaster@lemmy.world
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            3 days ago

            They also wouldn’t want to be ambiguous. If I was trying to write this problem the a, b, c… would get replaced by something like a_1, a_2,…, a_26 to be clearer. This problem works as a fun gotcha but isn’t something that would come up in the real world.

      • shastaxc@lemm.ee
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        3 days ago

        Assuming both x represent the same number. There’s no reason to assume the ellipses should include x-x. Why would alphabetic order be involved at all?

        • pyre@lemmy.world
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          3 days ago

          have you never taken math? I’m seriously asking because you’re incredibly wrong in both statements.

            • nyctre@lemmy.world
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              2 days ago

              So your argument is that in the list “a, b, c, …, z” the “…” Bit could be anything and we have no way of knowing what’s there and therefore the problem is unsolvable? Or what are you saying exactly?

              • shastaxc@lemm.ee
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                2 days ago

                Yes. The variables a, b, c, and z must have a stated correlation. Variable names do not implicitly have any relation between them. Ellipses work for numbers because a series of 1, 2, 3 … 100 can be inferred using the rules of mathematics. A series of a, b, c … z cannot; the series can only be inferred using the rules of the English language.

                • pyre@lemmy.world
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                  2 days ago

                  so is the word “simplify”. I guess we’ll never know what they mean by that because if you pretend you don’t speak English, then there’s no way of knowing!

                • nyctre@lemmy.world
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                  2 days ago

                  Right. Well, yeah, I guess your pedantic response is a lot more logical than the intended answer that other people have pointed out. Have a nice day!