123 reputation
5
bio website kutulu.org
location Florida
age 38
visits member for 2 years, 4 months
seen 23 hours ago

Jun
11
comment Use of the word “solve”?
oddly enough, in English we "take" derivatives but not integrals....
Apr
7
awarded  Popular Question
Mar
19
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".
Mar
14
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.
Jan
2
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?
Oct
12
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.
Sep
30
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...
Sep
30
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...
Sep
29
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)?
Sep
29
asked What does $d/dx$ actually mean?
Sep
2
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
Jul
29
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.
Jun
11
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.
Jun
11
comment My sister absolutely refuses to learn math
@JoelReyesNoche if I could +10000 this answer I would.
May
26
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 :)
May
21
awarded  Commentator
May
21
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." :)
Mar
31
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.
Aug
29
comment Why does the logarithm require a special notation?
@MJD +1 for the examples; I think an explicit mention of the fact that there are actually several "special notations" for logarithms is right on-topic for this question and would make a good addition to your answer.
Jul
5
comment why have we chosen our number system to be decimal (base 10)
@Jens you're pretty much right on; Europes use of place-valued base-10 numbers comes from the Arabic numbers, which were introduced by The Pope in ~1000AD. You don't get a bigger stick in Middle Ages Europe than the Church. (It also made accounting easier, which was why powerful people tended to like them and teach their kids how to use them)