dat_math [they/them]

  • 11 Posts
  • 274 Comments
Joined 3 years ago
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Cake day: July 9th, 2021

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  • and wants to know why 0.999… = 1

    \begin{align} 0.999… &= 9\cdot(0.1+0.01+0.001+… ) \ &= 9\cdot( 0.1^1 + 0.1^2 + 0.1^3 + … ) \ &= 9\cdot(\sum\limits_{i=1}^\infty ( \frac{1}{10^i} ) ) \ &= 9\cdot(\sum\limits_{i=0}^\infty ( \frac{1}{10^{(i+1)}}))\ &= 9\cdot(\sum\limits_{i=0}^\infty \frac{1}{10}*(\frac{1}{10^i})) \ &= \frac{9}{10}\cdot (\sum\limits_{i=0}^\infty (\frac{1}{10^i})) \ &= \frac{9}{10}\cdot \frac{1}{(1-(\frac{1}{10}))}\ &= \frac{9}{10}\cdot \frac{10}{9} = 1 \end{align}

    The crux rests on a handy result on from calculus: the sum of an infinite geometric series looks likes s = 1/(1-r), when s = \sum\limits_k=0^inf r^k, and |r| < 1.

    Sorry for the latex. When will hexbear render latex? This is a bit more readable:


  • What are your top 2?

    Idk. I make a different bean chili in the pressure cooker every week with whatever veggies I can get and whatever variety of beans we have on hand (which is usually a lot because I’m fortunate enough to live in a place with an absurd variety of plant agriculture). We vary the profile of the chili between a few indian-ish seasoning mixtures, this tasty african mixture with a ton of cumin and ras-al hanout, mexican-ish spices, and a few other blends. I use this to make a lot of burritos and tacos. Occasionally we’ll mix them into patties but that’s a huge chore. When my partner or I feel bored with these, we pick a place on a map and try to learn a recipe or two from there and then mix a chili with that dish’s flavors.

    Aside from the chili, we’ve been making a lot of indian recipes:

    this shit is amazing, but it’s a rare treat for me:


  • Insects also have brains. Some arachnids have the capacity for fairly complex cognition (e.g., the portia spider’s hunting behaviors, jumping spiders communicate with eachother and in my opinion, engage in playful behavior).

    The issue isn’t with your terminology, but rather with what it reveals about the imprecision/inconsistency of your reasoning on these matters.

    If you’re going to draw a line at eating beings that can feel the harm done to them by eating, it might serve you to explore that boundary more thoroughly.