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Dec
23
comment Proving order in real number set
Depends on the definition of $\le$
Dec
23
revised Find $f(x)$ where $ f(x)+f\left(\frac{1-x}x\right)=x$
added 2 characters in body; edited title
Dec
23
answered Show that $\alpha^2 + \alpha - 1$ is a zero divisor in $R$
Dec
23
answered Area of an equilateral triangle divided by three lines
Dec
22
comment Why are conjectures about the primes so hard to prove?
If those things were not hard to prove, they won't be conjectures anymore ...
Dec
22
comment Who came up with the $\varepsilon$-$\delta$ definitions and the axioms in Real Analysis?
Historically, Leibniz/Newton started this, though rigor (in the form of $\epsilon\delta$) was added only later by Weierstrass. For an alternative (possibly matching better what Leibniz/Newton had in mind) see Robinson's hyperreal.
Dec
22
comment How to show this polynomial is less than zero?
Rewrite as $Ny(y-1)^2-y-y^{2N+3}+y^{N+1}(N^2y(y-1)^2+N(y-1)^2+1)$ for a start
Dec
22
comment $a,b,n,d\in \mathbb N$. $a,b,d$ are different numbers from the interval $(n^2;n^2+n)$. Prove that it can't be true that $d|ab$.
@MatikKen I removed "random" because an absolute statement ("can't be true") is made. I assume "arbitrary" was meant.
Dec
22
revised $a,b,n,d\in \mathbb N$. $a,b,d$ are different numbers from the interval $(n^2;n^2+n)$. Prove that it can't be true that $d|ab$.
deleted 2 characters in body; edited title
Dec
22
revised Are universal quantified statements defined for inequalities even if the inequality is undefined?
added 1068 characters in body
Dec
22
answered $A\subset \mathbb{R}$ with more than one element and $A/ \{a\}$ is compact for a fixed $a\in A$
Dec
22
comment Differentiability of a certain piecewise function
@Belov Of course it has, though only at $x=0$.
Dec
22
comment Differentiability of a certain piecewise function
Indeed $\pm x^2$ would have worked as well
Dec
22
answered Value of $ \frac{a^2 + b^2 + c^2}{ac^2 - ab^2} $
Dec
21
answered Proving with epsilon for a continuous function
Dec
21
reviewed Approve How prove this inequality $f(a)\le f(b)$
Dec
20
comment How would you create a math class that centers on the cultural experiences of African American and Latino students
Are you asking for differences between afro-american vs. latino vs. kaukasian or rich vs. poor? For example, those (presumably afro-amaerican9 rap artists and basketball players may well have yachts ...
Dec
20
comment theory of equations finding roots from given polynomial
The problem is badly formulated. I would prefer it if the condition "and $|a|=6, |b|=4$" were added.
Dec
20
comment Integers $n$ such that $i(i+1)(i+2) \cdots (i+n)$ is real or pure imaginary
Some heuristics and very rough eyeballing: As the absolute value of the product is $> n!$, the probability of landing less than $\frac12$ away from an axis on such a large circle is fairly low, $< \frac 4{2\pi n!}$. The sum of all these probabilities is $<\frac {2e}\pi$, so "less than two" solutions is about what we can expect.
Dec
20
answered Condition For A Set Having A Smallest Element