Michael Edenfield
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 Dec23 comment What's behind the Banach-Tarski paradox? +1 because I can upvote for any reason I feel like? Oct7 asked Choice of bounds for functions “defined” as integrals using the FTC Jun11 comment Use of the word “solve”? oddly enough, in English we "take" derivatives but not integrals.... Apr7 awarded Popular Question Mar19 comment Is a brute force method considered a proof? @camel brute force proofs, in general, are frowned upon not just because the chance of errors is much greater (which is one reason), but also because it tends to imply that there is no fundamental mathematical "reason" why the proof works, it "just so happens to work" for every possible case. IOW, there is a vague notion that a brute force proof is "a valid proof of a now provably-boring statement". Mar14 comment Does an equation containing infinity not equal 0 or infinity exist? @KRyan no, you can produce a limit that shows $\infty^0$ to be anything you want; for example, $$\lim_{x\to\infty} x^{1/ln x} = \infty^0 = e$$ This is why such expressions are called "indeterminate forms"; there's not enough information in $\infty^0$ to determine a single value for it. Jan2 comment Taking seats on a plane: probability that the last two persons take their proper seats I'm confused how you got the term for case 3, since the "rules" for seating aren't recursive; in particular, if passenger #2 finds his seat empty (passenger #1 did not take it) then #2 will always sit there, so the probability that #2 sits in the correct seat is (n - 1)/n, not 1/(n - 1)... isn't it? Oct12 comment Is zero irrational? @Stefan4024 it's definition varies with the branch of mathematics you're using; it would be undefined in algebra, but in calculus (where we have limits) it represent a limit of zero. Sep30 comment What does $d/dx$ actually mean? @PedroTamaroff so if my question has been asked and answered on here before I cannot find it, so I would appreciate any pointers... Sep30 comment What does $d/dx$ actually mean? @PedroTamaroff I've read lots of questions/answers that talk about $d/dx$ and all of them reinforce my intuition that it's an operator, not a numeric value you can do arithmetic on... Sep29 comment What does $d/dx$ actually mean? @JonasMeyer thanks, that looks like interesting information; but I got lost by sentence three of the answer :) I assume that stuff is from linear algebra (next on my list)? Sep29 asked What does $d/dx$ actually mean? Sep2 comment $2d^2=n^2$ implies that $n$ is multiple of 2 related to my earlier question (why this only works for prime numbers): math.stackexchange.com/q/162119/29313 Jul29 comment Set notation confusion (Empty Sets) @Bobby it helps (me, at least) to remember the name: the empty set is not "nothing" because it is still a set. All sets contain n other things; the empty set is a set, which contains 0 other things. Jun11 comment My sister absolutely refuses to learn math The most important part of your entire answer, IMO, was that the OP needs to show some willingness to help with her immediate needs, or she will just stop asking for help. Jun11 comment My sister absolutely refuses to learn math @JoelReyesNoche if I could +10000 this answer I would. May26 comment Does half-life mean something can never completely decay? @DanZimm He's actually asking about the pharmacological half-life, which is slightly different from the nuclear half-life. In particular, it's far less regular and predictable :) May21 awarded Commentator May21 comment What is a proof? @dkbose The only thing that really stops you from doing that on an exam is that your professor will probably fail you :) I took an MIT OCW course on discrete math where the professor said basically that: "You can use any basic rules of math that you already knew coming into this course as an axiom in your proofs, as long as you don't claim to 'already know' everything we're asking you to prove." :) Mar31 comment What does the notation $f\colon A\to B$ mean? I had the same question, though to me the meaning was pretty obvious from context I cannot figure out which "pre-req" class I should have learned this notation in. I did up through multi-dimensional calculus in college without ever seeing it, but when I started a discrete math course online it was taken for granted.