User user84413

11

17

votes

4

answers

1k

views

Showing that $Q_n=D_n+D_{n-1}$

combinatorics permutations

Apr 2 '19 at 15:12 darij grinberg 15.1k

3

11

votes

3

answers

391

views

Evaluating $\displaystyle\int_0^1\frac{\sqrt{1-y^2}}{1+y^2}dy$ without trig substitution

calculus integration

Jun 10 '15 at 18:26 Jack D'Aurizio 329k

3

10

votes

4

answers

277

views

Show that $(1+\frac{1}{n})^n+\frac{1}{n}$ is eventually increasing

calculus sequences-and-series

Oct 5 '15 at 1:19 Community♦ 1

4

9

votes

1

answer

578

views

Does the minimum of two decreasing divergent series diverge? [duplicate]

calculus sequences-and-series

Jun 23 '15 at 19:33 Community♦ 1

4

8

votes

4

answers

294

views

Finding $\int\frac{1}{x^{11}+4x^6}dx$

calculus integration indefinite-integrals partial-fractions substitution

Sep 1 '15 at 17:21 Community♦ 1

4

7

votes

2

answers

1k

views

Defining vertical tangent lines

calculus soft-question definition

Jan 21 '16 at 5:00 Community♦ 1

5

7

votes

1

answer

314

views

Reference request: Behavior of power series at endpoints

calculus real-analysis reference-request

Jan 21 '14 at 8:49 Sempliner 2,225

1

7

votes

3

answers

2k

views

Calculating an improper integral as a limit of a sum.

calculus

Jul 23 '13 at 5:13 coffeemath 28.7k

1

5

votes

2

answers

102

views

Find the values of $k$ for which $\sqrt{1+\frac{k}{n}}$ is irrational for all $n\in\mathbb N$

elementary-number-theory radicals rationality-testing

Aug 12 '15 at 18:31 Bart Michels 23.1k

1

4

votes

2

answers

712

views

Grouping terms of a series with the same sign

calculus sequences-and-series

May 18 '16 at 15:57 Community♦ 1

1

4

votes

2

answers

223

views

Counting numbers of fruit baskets

combinatorics discrete-mathematics generating-functions

May 11 '16 at 22:19 Community♦ 1

4

votes

1

answer

77

views

Arranging the letters of INCONVENIENCE so that no C is adjacent to an N

combinatorics discrete-mathematics

Jul 18 '15 at 23:59 Empy2 44.6k

5

4

votes

1

answer

168

views

Showing that a recursively defined sequence is decreasing.

sequences-and-series recurrence-relations

Jun 2 '15 at 13:40 Community♦ 1

4

votes

3

answers

149

views

Using the definition to show that $D_{x}(e^x)=e^x$.

calculus

Jan 20 '15 at 0:11 N. S. 125k

3

votes

3

answers

283

views

Arranging marbles in a row so that every red marble is adjacent to a green marble.

combinatorics discrete-mathematics

Sep 13 '15 at 6:02 Community♦ 1

1

3

votes

2

answers

1k

views

number of triangles determined by a rectangular grid

combinatorics discrete-mathematics

Jul 27 '15 at 15:38 Community♦ 1

1

3

votes

1

answer

107

views

finding $\int\frac{1}{(t^2+25)^2} dt$ without trig substitution

calculus integration

Jan 30 '15 at 16:28 Pp.. 5,558

1

2

votes

2

answers

339

views

Prove the identity $\sum\limits_{r=0}^n\binom{n}{r}\binom{m+r}{l}=\sum\limits_{r=0}^n\binom{n}{r}\binom{m}{r+l-n}2^r$ for $m,n\in\mathbb{N}$

combinatorics binomial-coefficients

Dec 28 '16 at 5:40 Community♦ 1

1

2

votes

2

answers

55

views

For which values of $a$ does $d\ge ac\ln c\implies d\ge c\ln d$?

calculus real-analysis inequality logarithms

Jun 28 '16 at 23:27 Community♦ 1

2

votes

2

answers

402

views

maximizing the area of a triangle with given angle and opposite side

algebra-precalculus geometry trigonometry

Dec 23 '15 at 19:41 Lee Mosher 82.8k

2

votes

1

answer

86

views

number of patterns of suit distributions in bridge deal

combinatorics discrete-mathematics

Sep 9 '14 at 23:56 vadim123 80.1k

2

votes

1

answer

132

views

verifying extrema found by Lagrange multipliers

calculus multivariable-calculus inequality

Aug 10 '14 at 23:20 Community♦ 1

1

2

votes

1

answer

2k

views

Proving that $\mathbb{R}$ satisfies the Least Upper Bound property.

real-analysis

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2

votes

4

answers

4k

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Separating 18 people into 5 teams

probability combinatorics

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1

vote

5

answers

763

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Showing that if $p$ is a prime and $p\mid ab$, then $p\mid a$ or $p\mid b$

elementary-number-theory

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1

vote

9

answers

1k

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Finding a formula for a repeating sequence of 1's and -1's

sequences-and-series

Nov 1 '16 at 16:01 Lolololololl 1

1

vote

1

answer

80

views

Notation for $\{n\in\mathbb{Z}:n\ge m\}$ for a given $m\in\mathbb{Z}$

notation

Nov 14 '15 at 17:14 Community♦ 1

1

vote

2

answers

95

views

“Proof” that $(2n)!$ is divisible by $2^n 5^{n-3}$ for $n\ge3$

elementary-number-theory induction fake-proofs

Sep 2 '15 at 17:39 Monty Hall 1,013

3

1

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3

answers

157

views

Simplifying $\displaystyle\sum_{k=0}^{20}(k+4)\binom{23-k}{3}$

combinatorics summation binomial-coefficients

Jul 30 '14 at 6:08 Martin Sleziak 52.2k

1

vote

1

answer

43

views

$\lim_{n\to\infty}a_n$ and Cauchy condensation

sequences-and-series

Nov 22 '13 at 16:29 N. S. 125k

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32 Questions

Showing that $Q_n=D_n+D_{n-1}$

Evaluating $\displaystyle\int_0^1\frac{\sqrt{1-y^2}}{1+y^2}dy$ without trig substitution

Show that $(1+\frac{1}{n})^n+\frac{1}{n}$ is eventually increasing

Does the minimum of two decreasing divergent series diverge? [duplicate]

Finding $\int\frac{1}{x^{11}+4x^6}dx$

Defining vertical tangent lines

Reference request: Behavior of power series at endpoints

Calculating an improper integral as a limit of a sum.

Find the values of $k$ for which $\sqrt{1+\frac{k}{n}}$ is irrational for all $n\in\mathbb N$

Grouping terms of a series with the same sign

Counting numbers of fruit baskets

Arranging the letters of INCONVENIENCE so that no C is adjacent to an N

Showing that a recursively defined sequence is decreasing.

Using the definition to show that $D_{x}(e^x)=e^x$.

Arranging marbles in a row so that every red marble is adjacent to a green marble.

number of triangles determined by a rectangular grid

finding $\int\frac{1}{(t^2+25)^2} dt$ without trig substitution

Prove the identity $\sum\limits_{r=0}^n\binom{n}{r}\binom{m+r}{l}=\sum\limits_{r=0}^n\binom{n}{r}\binom{m}{r+l-n}2^r$ for $m,n\in\mathbb{N}$

For which values of $a$ does $d\ge ac\ln c\implies d\ge c\ln d$?

maximizing the area of a triangle with given angle and opposite side

number of patterns of suit distributions in bridge deal

verifying extrema found by Lagrange multipliers

Proving that $\mathbb{R}$ satisfies the Least Upper Bound property.

Separating 18 people into 5 teams

Showing that if $p$ is a prime and $p\mid ab$, then $p\mid a$ or $p\mid b$

Finding a formula for a repeating sequence of 1's and -1's

Notation for $\{n\in\mathbb{Z}:n\ge m\}$ for a given $m\in\mathbb{Z}$

“Proof” that $(2n)!$ is divisible by $2^n 5^{n-3}$ for $n\ge3$

Simplifying $\displaystyle\sum_{k=0}^{20}(k+4)\binom{23-k}{3}$

$\lim_{n\to\infty}a_n$ and Cauchy condensation