• DacoTaco@lemmy.world
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    1 year ago

    Before i ask my question, know that my math is all the way in the back of my head and i didnt get too far in math at school.

    Wdym irrational numbers dont work? -3 * -pi would be the same as 3*pi, no?
    I always assumed if all factors of the multiplication are negative, it results in the same as the positive variant, no matter the numbers ( real, fractal, irrational, … )

    • myslsl@lemmy.world
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      1 year ago

      Multiplying two negative irrational numbers together will still give you a positive number, it’s just that you can’t prove this by treating multiplication as repeated addition like you can multiplication involving integers (note that 3 is an integer, 3 is not irrational, the issue is when you have two irrationals).

      So, for example with e * pi, pi isn’t an integer. No matter how many times we add e to itself we’ll never get e * pi.

      Try it yourself: Assume that we can add e to itself k (a nonnegative integer) times to get the value e * pi. Then e * pi = ke follows by basic properties of algebra. If we divide both sides of this equation by e we find that pi=k. But we know k is an integer, and pi is not an integer. So, we have reached a contradiction and this means our original assumption must be false. e * pi can’t be equal to e added to itself k times (no matter which nonnegative integer k that we pick).

    • Rodeo@lemmy.ca
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      1 year ago

      I think all they mean is you can’t write it out since irrational numbers have no end.

      You’re correct in that the principle still applies in exactly the same way.