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27m
revised Argand diagram intersection of point p
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29m
comment Trace of a certain matrix
If the eigenvalues are not required to be in ${\bf Z}_{227}$, then I don't see how one can answer this question.
33m
comment Why null space and column space?
I think you mean "null space and column space of a matrix," Justin.
34m
comment Shortest distance from a point to vertices of a cube
I think you've written $O(p)$ where you meant $O(d)$.
3h
comment Anti-symmetric relation given by a matrix
I take it the ones represent pairs in the relation, and the zeros represent pairs not in the relation. So $(2,3)$ and $(3,2)$ are not in the relation.
3h
comment Proof of taking derivatives of both equal sides
"at any point $(a,b,c)$" doesn't make sense if $f$ is a function of 2 variables. How do you evaluate $f(x,y)$ at $(a,b,c)$?
9h
comment Know eigenvalues, get $Q$ of $A=QLQ'$
The vector $(1/7)(2,4,5)$ does not have norm 1.
9h
comment Check if the angle is constructable
Well, do you know the cosine of 30 degrees? and is it a constructable number? Better yet: do you know how to construct an equilateral triangle? and how to bisect an angle? The formula for $\cos3\theta$ is really overkill, if all you're interested in is 30 degrees.
11h
comment solve this congruence please.
The congruence I wrote down implies the left side is odd, so $6-n$ is odd, so $n$ is odd. When $n$ is odd, $7^n\equiv-1\pmod4$, so we need $6-n\equiv3\pmod4$.
21h
comment How to show that the vertices of a convex hull are given by these specific subsets…
Asking it here is fine BUT only if you link it to the MO post so people here can benefit from what was written there (and so people here won't waste your time by telling you things you were already told there).
21h
comment How can I have a copy of this old paper?
Funny, it got an answer on MO, mathoverflow.net/questions/185045/…
21h
comment How to show that the vertices of a convex hull are given by these specific subsets…
Previously posted to MO, mathoverflow.net/questions/185009/… where it got closed but did attract some comments.
21h
comment Solving a Complex Number polynomial problem
The last equation you have written down is certainly nonsense.
21h
comment How can I find fifth root of unity?
You're gooing to have a hard time proving $1+a^2+a^3+a^4=0$. You'll have better luck with $1+a+a^2+a^3+a^4=0$.
21h
comment solve this congruence please.
$7^n(6-n)\equiv1\pmod4$, $n$ must be 3 modulo 4.
21h
comment Check if the angle is constructable
$\cos x$ may be transcendental, and not satisfy any polynomial (in which case, it won't be constructable).
21h
comment Integral Contest
This question appears to be off-topic because m.se is not for running contests.
1d
comment Know eigenvalues, get $Q$ of $A=QLQ'$
If $A$ is symmetric (as it is in your example), then $Q$ can be taken to be orthogonal (which is the same as $Q^{-1}=Q^t$). To get such $Q$, you have to get orthonormal eigenvectors. One way to do that is to apply the Gram-Schmidt process to the eigenvectors you found.
1d
revised Calculating the Growth of A Small Population After 1000 Years
edited tags
1d
revised The product of uniformly continuous functions is not necessarily uniformly continuous
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