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Sep
15
comment Combinatorics (Yahtzee)
A large straight is "2-3-4-5-6". But it does not matter which of the dice is 2, which is 3, which is 4, and so on. It just matters that each of those numbers appears. The same is true for all others. In no single case does the score depend on the order.
Sep
15
comment Why is the expression $\underbrace{n\cdot n\cdot \ldots n}_{k \text{ times}}$ bad?
With the underbrace notation, it's not at all clear what $n^0$ is.
Sep
14
revised Write the Fourier series to $f(t)=|\sin t|$
Improved math formatting
Sep
14
comment Evaluating the integral $\int_0^\pi 9\sin^2t\cos^4t\,\mathrm{d}t$
Well, a start could be to look at the different integration rules, and check which one might be applicable.
Sep
14
comment Combinatorics (Yahtzee)
You seem to know a different type of Yahtzee than I do: In the version I know, the order doesn't matter (indeed, you throw all five dice at once, and they are indistinguishable, therefore there's no way to even establish an order).
Sep
14
answered Comparing the size of square roots
Sep
13
answered Set containing all rings!
Sep
7
answered How to find the outermost points in an ellipse?
Sep
7
comment Solve $n^4>3^n$
@shengy: Just take both sides to the power of $1/(4n)$.
Sep
7
answered Quantum mechanics, conmutative operators.
Sep
7
answered It seems obvious, but how to prove it formally?
Sep
7
revised Does $V_1,V_2,V_3$ span $R^4$
Fixed LaTeX syntax for matrices
Sep
7
comment How to write such a constraint?
Would inequalities be acceptable as constraints? Specifically I think $x_{ij}x_{jk} \le x_{ik}$ would work.
Sep
7
answered Set Theory - How do I solve this problem?
Sep
6
comment Calculating the signature of matrix A?
But is it also easier to subtract three times the first row from the last one, than it is to subtract three times the last row from the first one?
Sep
6
comment Calculating the signature of matrix A?
Given that the first two steps just turn the matrix upside down, I don't see how they make anything easier.
Sep
6
comment Calculating the signature of matrix A?
What are the first two steps for?
Sep
6
answered Is there a thing named a “spiral plane” which is a plane but it's spiral?
Sep
6
revised Find the domain of the function $f(x) =\frac{x+4}{x^2-9}$
TeXified
Jul
16
comment What makes induction a valid proof technique?
And how do you show that $k^2<k$ if $0<k<1$?