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Yos
  • Member for 6 years
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11 votes
7 answers
3k views

Product of functions is $0$ but none of the functions is identically $0$?

5 votes
2 answers
141 views

generating function: how many possibilities are there to throw 10 different dice so that their sum is 25

5 votes
3 answers
164 views

Matrix determinant as Dickson polynomial $\frac{x^{n+1}-y^{n+1}}{x-y}$

5 votes
3 answers
11k views

How to solve $y''+y=\cos x$?

4 votes
1 answer
910 views

How to prove that 3-CNF is satisfiable using Hall's marriage theorem?

4 votes
1 answer
581 views

Prove that $I-T$ is an isomorphism if $T:V \to V$ and $T^3=0$ and find $(I-T)^{-1}$

4 votes
3 answers
345 views

Is $T(p(x))=p(x+1)$ a linear map if $T:\mathbb{R}[x]\to\mathbb{R}[x]$?

4 votes
1 answer
536 views

How many natural solutions to $x_1 + x_2 + x_3 + x_4 + x_5 + x_6 = 24$ if $x_1 + x_2 + x_3 > x_4 + x_5 + x_6$?

4 votes
2 answers
765 views

How to solve system of linear equations with negative scalars over finite field?

4 votes
3 answers
1k views

How to find the number of solutions to a system of equations with one parameter which cannot be reduced?

3 votes
2 answers
167 views

Prove if $B^2=I+BA$ and $A^2=AB$ then $A=0$

3 votes
2 answers
170 views

Find $\dim(\ker T_1 \cap \ker T_2)$ if $T_1,T_2:V\to F$, $T_1 \neq 0$, $T_2\neq 0$, $\dim V=n$ and $\ker T_1\neq \ker T_2$

3 votes
1 answer
338 views

How to find $\theta$ bounds when calculating the volume enclosed between sphere $x^2+y^2+z^2=4a^2$ and cylinder $x^2+(y-a)^2=a^2$?

3 votes
1 answer
106 views

How to solve $z^9-(\overline z)^9=9|z|^4$ over $\mathbb{C}$?

3 votes
2 answers
2k views

Find all the points on the cone $z^2=x^2+4y^2$ that are the closest to the point $(0,0,c)$

3 votes
1 answer
122 views

How to prove that $W=U_1 \oplus(U_2 \cap W)$ if $U_1 \subseteq W$, given that $V=U_1 \oplus U_2$ and $U_1,U_2,W$ are subspaces of $V$?

3 votes
2 answers
2k views

Can the degree sequence $2,2,2,2,2,3,3$ be Hamiltonian graph, if not can it be a simple graph?

3 votes
2 answers
675 views

How many labeled trees are there if there're $4$ leaves that are set?

3 votes
1 answer
3k views

How to calculate line integral over an ellipse with vector field undefined inside the ellipse?

3 votes
2 answers
356 views

How to calculate $\iint\ln(x^2+y^2)$ over a part of a circle?

3 votes
1 answer
1k views

Find shortest path in graph that visits 2 nodes from a certain node set

3 votes
1 answer
383 views

How many permutations of $0123456789$ are possible if $0123$, $2345$, $4567$, $6789$ sequences are not allowed?

2 votes
2 answers
167 views

How to prove that if a graph and its complement graph are trees then there're $4$ vertices in the vertex set of the graphs?

2 votes
2 answers
187 views

How to prove that if a simple graph has a vertex which splits it into at least $2$ connected components does not have Hamiltonian cycle?

2 votes
1 answer
476 views

How many positive integer solutions are to a system of linear equations?

2 votes
1 answer
839 views

How to find the equivalence classes of a formal language complement?

2 votes
2 answers
64 views

How to define a grammar which creates a language from words of another grammar without one of the letters?

2 votes
2 answers
54 views

Give an example of a language $L$ where $\min(\max L)\neq \max(\min L)$

2 votes
1 answer
244 views

How to find minimum Hamming distance of concatenated two encoded words?

2 votes
2 answers
49 views

Does the curve $c(t)=\langle \sqrt{1-t^2}\cos t,\sqrt{1-t^2}\sin t,t\rangle$ lie on unit sphere?

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