User trombho

7 votes

0 answers

145 views

Conjecture: There is no $n\neq3$ such that $\arctan(1)+\arctan(2)+\cdots+\arctan(n)=\frac{k\pi}{2}$, with $k$ integer.

trigonometry conjectures

asked Sep 16, 2019 at 1:22

5 votes

3 answers

158 views

Area triangle (possible)

geometry euclidean-geometry

asked Nov 15, 2019 at 23:21

5 votes

3 answers

360 views

Calculate the value of angle $ACB$

geometry trigonometry

asked Dec 20, 2019 at 14:22

4 votes

1 answer

247 views

Midpoints, bisectors, orthocenter, incenter and circumcenter

geometry contest-math euclidean-geometry problem-solving

asked Nov 4, 2019 at 3:56

4 votes

1 answer

347 views

Greatest prime divisor of $ n^2+1$

number-theory prime-numbers divisibility gcd-and-lcm

asked Oct 8, 2019 at 13:51

4 votes

2 answers

120 views

Number primes digits

number-theory prime-numbers

asked Oct 8, 2019 at 21:24

3 votes

1 answer

312 views

Find all integers

number-theory arithmetic

asked Sep 20, 2019 at 13:57

3 votes

2 answers

56 views

Numeric combination

combinatorics

asked Nov 17, 2019 at 14:54

2 votes

2 answers

121 views

Travel Logic (mod. 4)

combinatorics logic graph-theory arithmetic

asked Nov 17, 2019 at 17:07

2 votes

1 answer

123 views

Mansion point and incenter

geometry contest-math euclidean-geometry

asked Nov 16, 2019 at 11:28

2 votes

1 answer

101 views

Inequality with 5 cyclic variables

inequality summation a.m.-g.m.-inequality tangent-line-method

asked Nov 17, 2019 at 2:00

2 votes

1 answer

206 views

$99 \times 99$ colored square grid

combinatorics proof-verification combinations arithmetic combinatorial-proofs

asked Oct 29, 2019 at 18:41

2 votes

2 answers

77 views

Showing that successive arches of $y=e^{-\alpha x}\sin\beta x$ bound areas in geometric progression with ratio $q=e^{-\alpha\pi/\beta}$

calculus trigonometry contest-math trigonometric-integrals geometric-progressions

asked Oct 12, 2019 at 0:54

2 votes

2 answers

301 views

Pairs of perfect squares

number-theory contest-math square-numbers

asked Oct 17, 2019 at 17:52

2 votes

1 answer

45 views

Calculate the optimal ratio AX/AB

geometry contest-math euclidean-geometry

asked Oct 20, 2019 at 21:57

2 votes

2 answers

624 views

Cubic diophantine equation with a prime $x^3 + y^3 + z^3 - 3xyz = p$.

elementary-number-theory arithmetic diophantine-equations cubics symmetric-polynomials

asked Sep 10, 2019 at 18:32

2 votes

3 answers

108 views

Numerical bases and prime number theory

number-theory number-systems

asked Sep 24, 2019 at 22:19

2 votes

1 answer

56 views

Prime Number Theory (Dividers)

number-theory systems-of-equations

asked Sep 25, 2019 at 19:04

2 votes

0 answers

40 views

Numbering system [closed]

number-theory prime-numbers number-systems

asked Sep 26, 2019 at 21:09

2 votes

2 answers

86 views

Prove that $a = b$ [duplicate]

elementary-number-theory contest-math divisibility

asked Oct 11, 2019 at 13:50

2 votes

2 answers

187 views

Numeric sequence [duplicate]

contest-math number-systems

asked Oct 3, 2019 at 19:28

2 votes

1 answer

108 views

Solve the equation $x! + y!+z!= 2^{v!}$

number-theory proof-verification prime-numbers diophantine-equations

asked Oct 6, 2019 at 19:17

2 votes

1 answer

72 views

Square and rectangle

geometry arithmetic

asked Dec 22, 2019 at 12:11

2 votes

2 answers

209 views

Determine all pairs $(a, b)$ for which $s (an + b) - s (n)$ assumes finitely many values

elementary-number-theory decimal-expansion

asked Dec 20, 2019 at 5:13

2 votes

0 answers

69 views

Verification of my solution of the functional equation $ f \left( x + y ^ 2 \right) = f ( x ) +f ( y ) ^ 2 $

functions solution-verification functional-equations

asked May 1, 2021 at 14:11

2 votes

0 answers

62 views

Matching scientists and topics with certain restrictions

combinatorics graph-theory

asked May 21, 2021 at 11:58

2 votes

1 answer

109 views

Expected Value with RNG

probability combinatorics

asked May 21, 2021 at 12:14

2 votes

1 answer

53 views

Find a formula for $\int ^x _0 [t] \,dt$, $x>0$ real.

calculus integration

asked Sep 17, 2021 at 0:24

2 votes

1 answer

283 views

How many angles have integer measure in degrees and are interior angles of an integer-sided triangle?

geometry algebra-precalculus trigonometry euclidean-geometry

asked Dec 15, 2019 at 0:35

1 vote

3 answers

66 views

Determine the value of $\sum_{i=1}^{2019}\frac{x_i}{x_i-1}$

polynomials summation

asked Dec 18, 2019 at 14:11

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115 Questions

Conjecture: There is no $n\neq3$ such that $\arctan(1)+\arctan(2)+\cdots+\arctan(n)=\frac{k\pi}{2}$, with $k$ integer.

Area triangle (possible)

Calculate the value of angle $ACB$

Midpoints, bisectors, orthocenter, incenter and circumcenter

Greatest prime divisor of $ n^2+1$

Number primes digits

Find all integers

Numeric combination

Travel Logic (mod. 4)

Mansion point and incenter

Inequality with 5 cyclic variables

$99 \times 99$ colored square grid

Showing that successive arches of $y=e^{-\alpha x}\sin\beta x$ bound areas in geometric progression with ratio $q=e^{-\alpha\pi/\beta}$

Pairs of perfect squares

Calculate the optimal ratio AX/AB

Cubic diophantine equation with a prime $x^3 + y^3 + z^3 - 3xyz = p$.

Numerical bases and prime number theory

Prime Number Theory (Dividers)

Numbering system [closed]

Prove that $a = b$ [duplicate]

Numeric sequence [duplicate]

Solve the equation $x! + y!+z!= 2^{v!}$

Square and rectangle

Determine all pairs $(a, b)$ for which $s (an + b) - s (n)$ assumes finitely many values

Verification of my solution of the functional equation $ f \left( x + y ^ 2 \right) = f ( x ) +f ( y ) ^ 2 $

Matching scientists and topics with certain restrictions

Expected Value with RNG

Find a formula for $\int ^x _0 [t] \,dt$, $x>0$ real.

How many angles have integer measure in degrees and are interior angles of an integer-sided triangle?

Determine the value of $\sum_{i=1}^{2019}\frac{x_i}{x_i-1}$