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2h
answered Maximum number of linearly independent anti commuting matrices
3h
comment Proof that if 'a' and 'b' can be written as sum of two squares then so can lcm[a,b]
So, have you learned how the LCM of two integers relates to their prime factorizations?
3h
comment How to find the discrete probability vector given a transition probability matrix?
Author unresponsive to comments, question apparently abandoned.
3h
comment how to relate the eigenvalues and eigenvectors of these two matrices?
I posted an answer. Any thoughts about it?
3h
comment Ellipse Diagonal's Length/Equation
So I guess your ellipses are aligned with the major axis horizontal and the minor axis vertical. I would like to know how you define "most northwestern point". And I still want to know how the ellipse is given. If it's given as a drawing, about all you can do is take out a ruler and measure that "diagonal".
3h
comment Is $f(x)=x^{4}-2x^2 +3$ Eiseinstein in 2-adic $\mathbb{Q}_{2}$?
Making any progress toward finding another $\alpha$?
3h
comment Solve the initial value problem x'=Ax
Not really necessary to do any row reduction, was it?
3h
revised $r+r^{-1}$ integral implies $r^n+r^{-n}$ integral
more informative title
3h
comment Solve the initial value problem x'=Ax
Let $\lambda$ be either one of your eigenvalues. Compute the matrix $A-\lambda I$. An eigenvector is a nonzero element of the nullspace of that matrix. Do you know how to find an element in the nullspace of a matrix? For a $2\times2$ matrix, there is an exceedingly easy way to do this.
3h
comment $1+x^p+x^{2p}+\dotsb+x^{p(p-1)}$ irreducible
Probably a bad idea to use the symbol $p$ with two different meanings in one equation.
3h
comment Ellipse Diagonal's Length/Equation
Ellipses don't have diagonals. Do you mean the major axis? Finding the equation of and the length of the major axis will depend on what information you are given about the ellipse. How is the ellipse given?
3h
comment area of circle using circumference of inner circles
@Shahar, huh?${}$
3h
comment Labeling the vertices of a polygon with 0's and 1's
So, have you taken the suggestion of @Perry and looked at Polya enumeration?
4h
comment How to find $\int \frac {dx}{(x-1)^2\sqrt{x^2+6x}}$?
You have written $x-1=a$ and $a=x+1$ as if they were the same thing, but they're not. Also, you can always check whether an answer is correct by differentiating the answer and seeing whether you get back the original integrand.
4h
comment Group action problem.
If you replace (124) with (12), then you'll have a group.
4h
comment How do I go about showing the cardinality of two sets are the same?
Is this not a duplicate of math.stackexchange.com/questions/588190/…
4h
comment Limit to infinity of a function involving only gamma functions
It certainly makes sense to ask for $$\lim_{n\to\infty}{\Gamma((1/2)-n)\Gamma(1+n)\over\Gamma((1/2)+n)\Gamma(n)}$$ Whether it exists, or what it comes to, I don't know. What do you mean by "Oscillating between $\infty$ and $-\infty$"?
4h
comment partitioning numbers from 1 to n in 4 non-empty subsets so no subset has 2 consecutive numbers.
Sure, you just solve that recurrence. I gave you the general form of the solution in my comment on the question, you just have to work out $A,B,C$. And I think you'll find they've been worked out for you at the oeis page in my answer. Also, you can work out $S(n,3)$ by inclusion-exclusion, so there's a third way to get the formula.
4h
comment partitioning numbers from 1 to n in 4 non-empty subsets so no subset has 2 consecutive numbers.
I'm glad you found my answer helpful, user4140. You do have the option of voting it up.
4h
comment partitioning numbers from 1 to n in 4 non-empty subsets so no subset has 2 consecutive numbers.
@vonbrand, it appears that the number of unrestricted partitions into 3 parts equals the number of restricted partitions into 4 parts.