User kingW3

25 votes

4 answers

2k views

Nested radicals of 1000 square roots

algebra-precalculus nested-radicals

asked Feb 9, 2015 at 11:57

10 votes

1 answer

299 views

Prove that all light bulbs can't light off

combinatorics

asked Aug 3, 2014 at 11:09

10 votes

2 answers

492 views

When is a Sudoku like table solvable

combinatorics contest-math recreational-mathematics latin-square

asked Jun 12, 2017 at 12:44

7 votes

1 answer

231 views

Evaluting sum $\sum \limits_{n=0}^\infty\frac{n^k}{n!}$

sequences-and-series closed-form

asked Jan 18, 2015 at 18:35

6 votes

1 answer

190 views

How many sets $(A_1,A_2,\cdots, A_k)$ which are subsets of $\{1,2,\cdots ,n\}$

combinatorics contest-math

asked Feb 3, 2017 at 18:27

6 votes

4 answers

211 views

Solve equation $\frac{1}{x}+\frac{1}{y}=\frac{2}{101}$ in naturals

algebra-precalculus elementary-number-theory

asked Feb 11, 2016 at 18:03

5 votes

2 answers

2k views

Chess rook problem

combinatorics

asked Aug 18, 2014 at 12:31

4 votes

1 answer

223 views

Why is infinite Integration by Parts valid?

calculus integration recursion integration-by-parts

asked Apr 6, 2017 at 15:46

4 votes

4 answers

144 views

Using basis $e=[x^3,x^2,x,1]$ instead of $e=[1,x,x^2,x^3]$

linear-algebra matrices reference-request vector-spaces hamel-basis

asked Jul 5, 2018 at 8:49

3 votes

1 answer

96 views

Prove $fgh$ has more then $\deg f$ different zeroes

polynomials

asked Dec 12, 2016 at 17:14

3 votes

1 answer

3k views

Two circles touch internally

geometry circles

asked Feb 23, 2014 at 15:59

3 votes

1 answer

219 views

Cyclic quadrilateral geometry

geometry quadrilateral

asked Mar 1, 2014 at 22:23

3 votes

2 answers

356 views

Proving $a\mid b^2,\,b^2\mid a^3,\,a^3\mid b^4,\ldots\implies a=b$ - why is my approach incorrect

number-theory divisibility

asked Mar 8, 2014 at 13:25

3 votes

1 answer

60 views

Biggest common divisor

number-theory divisibility

asked Mar 23, 2014 at 22:06

3 votes

3 answers

70 views

Given a continuous mapping $f$ find $\lim_{n\to\infty}\int_0^1 nf(x)e^{-nx}$

calculus real-analysis continuity

asked Jun 12, 2018 at 15:09

2 votes

2 answers

158 views

Material for advanced highschooler

soft-question self-learning

asked Apr 17, 2014 at 15:34

2 votes

1 answer

182 views

Lerch transcendent: $\text{LerchPhi}^{(0,1,0)}\left(\frac{1}{2}, 0, 2\right)$

sequences-and-series notation closed-form

asked Aug 16, 2014 at 16:55

2 votes

1 answer

1k views

Minimum number of knights so that every cell is attacked

combinatorics

asked Jan 18, 2015 at 19:39

2 votes

0 answers

165 views

Biggest number divisible by $99$

algebra-precalculus elementary-number-theory proof-verification contest-math

asked Feb 25, 2015 at 18:17

2 votes

2 answers

44 views

Finding the interval after substitution

algebra-precalculus inequality exponential-function

asked Mar 5, 2015 at 18:47

2 votes

1 answer

368 views

Multivariable limit one-sided path

multivariable-calculus

asked Sep 19, 2015 at 12:24

2 votes

2 answers

136 views

Proving $x>\sin(x)$ without calculus for $x>0$

algebra-precalculus trigonometry inequality contest-math

asked Feb 1, 2016 at 11:01

2 votes

1 answer

1k views

Find invertible matrices $P,Q$ such that $A^0=PAQ$

linear-algebra matrices matrix-equations

asked Jan 25, 2018 at 18:40

2 votes

1 answer

92 views

Biggest number of creatures in forest

combinatorics contest-math

asked Jan 18, 2015 at 15:14

2 votes

1 answer

100 views

Intuition behind the formula for number of graphs with $n-3$ bridges

combinatorics graph-theory trees

asked May 12, 2018 at 20:58

1 vote

0 answers

71 views

Finding $(x,y)$ closest to $N$ points

optimization algorithms

asked Nov 30, 2018 at 17:36

1 vote

1 answer

71 views

Are given groups isomorphic

abstract-algebra group-theory finite-groups symmetric-groups group-isomorphism

asked Jan 9, 2019 at 16:28

1 vote

1 answer

90 views

Elementary solution to $4^x-25^y=39$ in natural numbers

algebra-precalculus elementary-number-theory

asked Jun 18, 2017 at 15:20

1 vote

2 answers

76 views

Compare $4^x+1$ and $2^x+3^x$ for non-negative real $x$

algebra-precalculus contest-math

asked Feb 25, 2015 at 18:47

1 vote

0 answers

81 views

Solving system of equations in rationals

linear-algebra matrices systems-of-equations

asked Aug 22, 2014 at 18:55

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41 Questions

Nested radicals of 1000 square roots

Prove that all light bulbs can't light off

When is a Sudoku like table solvable

Evaluting sum $\sum \limits_{n=0}^\infty\frac{n^k}{n!}$

How many sets $(A_1,A_2,\cdots, A_k)$ which are subsets of $\{1,2,\cdots ,n\}$

Solve equation $\frac{1}{x}+\frac{1}{y}=\frac{2}{101}$ in naturals

Chess rook problem

Why is infinite Integration by Parts valid?

Using basis $e=[x^3,x^2,x,1]$ instead of $e=[1,x,x^2,x^3]$

Prove $fgh$ has more then $\deg f$ different zeroes

Two circles touch internally

Cyclic quadrilateral geometry

Proving $a\mid b^2,\,b^2\mid a^3,\,a^3\mid b^4,\ldots\implies a=b$ - why is my approach incorrect

Biggest common divisor

Given a continuous mapping $f$ find $\lim_{n\to\infty}\int_0^1 nf(x)e^{-nx}$

Material for advanced highschooler

Lerch transcendent: $\text{LerchPhi}^{(0,1,0)}\left(\frac{1}{2}, 0, 2\right)$

Minimum number of knights so that every cell is attacked

Biggest number divisible by $99$

Finding the interval after substitution

Multivariable limit one-sided path

Proving $x>\sin(x)$ without calculus for $x>0$

Find invertible matrices $P,Q$ such that $A^0=PAQ$

Biggest number of creatures in forest

Intuition behind the formula for number of graphs with $n-3$ bridges

Finding $(x,y)$ closest to $N$ points

Are given groups isomorphic

Elementary solution to $4^x-25^y=39$ in natural numbers

Compare $4^x+1$ and $2^x+3^x$ for non-negative real $x$

Solving system of equations in rationals