114,504 reputation
7106211
bio website von-eitzen.de/math/tntrep.xml
location Bonn, Germany
age 48
visits member for 2 years, 1 month
seen 43 mins ago

I did study math and had a knack for it, but I am sooo out of that business now ...


1d
comment Prove By Induction (Fibonacci Sequence)
@Ron.J.Adams By applying any of the definitions of $\gcd$ or one step of the Euclidean algorithm
1d
answered What is and what represents a convergents function in polynomial form?
1d
answered Prove By Induction (Fibonacci Sequence)
1d
comment 8 questions on true/false quiz. Expected number of correct answers with a given probability of correct answer of a question “i”.
@DavidP. That was meant to reflect the definition of expected value $E(X)=\sum_k x_k(P(X=x_k)$ more properly, here with $P(X=1)=p$ and $P(X=0)=1-p$.
1d
answered 8 questions on true/false quiz. Expected number of correct answers with a given probability of correct answer of a question “i”.
1d
reviewed Reviewed 8 questions on true/false quiz. Expected number of correct answers with a given probability of correct answer of a question “i”.
1d
revised 8 questions on true/false quiz. Expected number of correct answers with a given probability of correct answer of a question “i”.
deleted 90 characters in body
1d
comment sign of roots of a quadratic equation with complex coefficients.
@Nilan $-a$ is the sum of the two roots, hence $\Re a>0$ is necessary.
1d
comment How can I prove the existence of an octagon/decagon/dodecagon?
dodecahedron or dodecagon?
1d
comment Proof of Soundness Lemma
The induction variable hides elsewhere, though: For a given $\Gamma$-proof, show that $\bar\nu(\phi_k)=T$ for all $k\le n$
1d
comment The product of uniformly continuous functions is not necessarily uniformly continuous
"If I attempt to prove $X$, the proof gets hairy" is not a valid method to prove $\neg X$.
1d
answered Calculating the Growth of A Small Population After 1000 Years
1d
comment Calculating the Growth of A Small Population After 1000 Years
100 people at what age? Babies for simplicity?
1d
answered Clarification on proof that all groups of order $< 60$ are solvable
1d
answered How to factor $x + 1 - 2 \sqrt x$?
1d
revised How to factor $x + 1 - 2 \sqrt x$?
edited title
1d
comment {$e_1, e_2, e_3, e_4$} be a standard basis in $R^4$. Does there exist a set of vectors $x_1, x_2, x_3$ such that
By the way, the notion of standard basis implies that is usually called the standard basis.
1d
comment Show that $-1$ is a square $\mod n$, if $n\equiv 1\mod 4$?
@Lullaby So what do you have to prove? Title (now) says "if $n\equiv 1\pmod 4$ then $-1$ is a square". Your comment says "If $-1$ is a square then $n\equiv 1\pmod 4$", question body says "if and only if". For two of the three variants my comment still applies: Can you find a number $x\in\{0,1,2,3,4,5,6,7,8\}$ such that $x^2+1$ is a multiple of $9$?
1d
answered Continuum Hypothesis?
2d
awarded  Necromancer