15,677 reputation
12042
bio website math.brown.edu/~lubinj
location Minnesota
age 78
visits member for 3 years, 3 months
seen 2 mins ago

Aged mathematician


Jan
19
revised If $x^2+x+1=0 $, then find the value of $(x^3+1/x^3)^3$?
corrected an embarrassing and misleading typo
Jan
19
revised Laurent series for $\frac1{z^2+1}$
There was a topo in the numerator of the outside factor of the last sum. I’ve cofrrected it. —Lubin
Jan
16
revised Is $\sqrt[3]{5}$ in $\mathbb Q(\sqrt[3]{2})$?
Gave alternative argument, by factoring 5.
Jan
13
revised Find the point on the curve farthest from the line $x-y=0$.
added 1 character in body
Jan
11
revised How many elements does $\mathbb Z_7[i]/\langle i+1\rangle$ have?
added 28 characters in body
Jan
5
revised Rationalizing the denominator in general
clarification
Nov
29
revised Determine the minimal polynomial of $\sqrt 3+\sqrt 5$
added 450 characters in body
Nov
28
revised Let $y^2 = x^3 + Ax + B$ be a curve and $y = m(x - x_1) + y_1$ tangent at $x_1$. Why is $x_1$ then a double root?
Complete rewrite!
Nov
7
revised Is there a rationality-preserving order isomorphism between $\mathbb{Q}$ and two disjoint open intervals?
Admitted that my “solution” of the problem was no such thing. Drat.
Nov
7
revised Is there a rationality-preserving order isomorphism between $\mathbb{Q}$ and two disjoint open intervals?
changed an insufficient answer to a sufficient one, I hope.
Oct
24
revised Question about laurent series
left off a crucial minus sign in a fmla
Sep
17
revised finding “exp(1)” in the p-adic numbers
slipped and gave the formal-group logarithm, not the genuine one. Now corrected
Aug
25
revised Disproving an “almost true” trigonometric identity
Gave an alternate, longer, less magical, proof.
Aug
25
revised Disproving an “almost true” trigonometric identity
deleted 14 characters in body
Aug
25
revised Disproving an “almost true” trigonometric identity
Correct two even more embarrassing careless errors
Aug
24
revised Disproving an “almost true” trigonometric identity
corrected an embarrassing error of elementary-school arithmetic.
Jul
11
revised Is $4x^2-4x+2$ surjective?
yet another embarrassing slip
Jul
7
revised Determine whether the intersection of surfaces is a parabola
Corrected an embarrassing slip.
Jul
2
revised I need a relation which is not reflexive, not symmetric, and not transitive
corrected mathematical error pointed out by amalloy
Jun
30
revised Show that $(x-\alpha)(x-\overline{\alpha})$ is a also a factor of $p(t)$ over the complex numbers
Corrected an embarrassing typo.