Jack M
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 Mar17 comment Why did it take mathematicians so long to discover non-Euclidean geometry? They didn't because they didn't. Why would they have? If you think it's obvious, I would simply respond that the fact that it went undiscovered for so long is in and of itself evidence that it isn't. Mar16 comment Constructing a pentagon from a circle What exactly is your question? Mar16 comment Group Permutations Proof @j.p. That's a (very nice) answer, not a comment. Mar16 comment What is ⌊0.9 recurring ⌋? The definition of the floor function is not "truncate all digits after the decimal point". Indeed, as you've just shown, such a function is not even well-defined - it depends on the particular decimal representation you choose. Mar15 comment What fraction is $\frac{2}{5}$ of $\frac{3}{4}$? It isn't emphasized enough in school that this is what multiplication of fractions is for. Mar13 comment Correct phrasing of a classic math problem Well, as it's clear from mvw's answer that the solution isn't unique, maybe this isn't the correct formulation after all. Mar12 comment The next prime is as far as possible @Slade That's an answer, not a comment! Mar12 comment why is PI considered irrational if it can be expressed as ratio of circumference to diameter? @user3573749 The question is somewhat meaningless - if we're talking about mathematics, then "theoretically" and "measure" are two words you shouldn't even be using in the same sentence! If you're measuring lengths, then you're outside of pure mathematics and into the physical world, where things are a lot messier. Philosophically, the problem is that it's not clear what "correct" means in your question. Mar12 comment Correct phrasing of a classic math problem @Poutrathor If we make no assumptions about the triangles, the problem is clearly unsolvable because any number of planes could be arranged into some formation that looks acceptably triangle-like. It's likely that the above is the type of triangle meant, since triangular numbers are well-studied. In any case, this assumption at least leads to a reasonable and interesting problem, although whether it has a unique solution remains to be seen. If it does, then I would consider that strong evidence that this is the formulation intended. Mar12 answered Correct phrasing of a classic math problem Mar12 comment Probability of a polynomial to be primitive Does the author mention what exactly the probability function is? Otherwise it's not clear how one should go about randomly picking integer polynomials. Mar9 comment Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? Why the insistence that they be irreducible? Mar8 comment Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? Okay, well what it boils down to is: what is the precise definition of "a radical expression" which rules out $\sqrt [3] 1$ yet includes the expression in the question? Mar8 revised Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? added 1 character in body Mar8 comment Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? @MattSamuel The notation $\sqrt [3] 1$ is ambiguous. It could just as well refer to any cube root of unity. And if you don't want any ambiguous expressions, then you can't even write $\sqrt{-3}$ in the above expression, because that's ambiguous too. Mar8 revised Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? added 2 characters in body Mar8 asked Why is $\sqrt [n] 1$ not an expression “in radicals” of a root of unity? Mar7 answered why is PI considered irrational if it can be expressed as ratio of circumference to diameter? Mar7 comment You need to buy 100 birds for \$100? how to find answer.. This problem can be solved using the same method I used on this question, but you probably haven't covered congruences yet. Mar7 comment How to prove the relation is transitive? @committedandroider You would probably want to prove that the sum of two numbers is even iff the numbers are the same parity (which would end up being as long as proving transitivity directly), but it has the advantage of making it clearer why the relation is transitive.