User kuch nahi - Mathematics Stack Exchange

bio	website
	location
	age	24
visits	member for	2 years, 2 months
	seen	Jun 8 '12 at 8:02
stats	profile views	566

	2,334 reputation	bio	website		visits	member for	2 years, 2 months
2833 badges		location			seen	Jun 8 '12 at 8:02

5

39

votes

4

answers

1

kviews

How to understand and appreciate the prime number industry?

nov 30 '11 at 17:58 Srivatsan 15.6k

7

20

votes

4

answers

737

views

Math behind rotation in MS Paint

rotations

jun 24 '11 at 9:49 Samuel 2,537

2

19

votes

1

answer

728

views

Do other non-native english speakers have trouble solving certain kinds of problems?

soft-question

jan 4 '12 at 18:51 j13r 111

4

13

votes

4

answers

742

views

Can I ever go wrong if I keep thinking of derivatives as ratios?

calculus

dec 1 '11 at 16:46 Srivatsan 15.6k

1

13

votes

2

answers

613

views

Puzzle: $(\Box @)+(\Box @) = (\Box\bigstar\Box$)

elementary-number-theory puzzle

dec 1 '11 at 0:02 Srivatsan 15.6k

13

votes

5

answers

745

views

$S=1+10+100+100+10000+… = -1/9$? How is that

sequences-and-series

mar 17 '11 at 16:05 yoyo 4,850

4

12

votes

5

answers

640

views

Evaluate $\sum\limits_{k=1}^n k^2$ and $\sum\limits_{k=1}^n k(k+1)$ combinatorially

combinatorics binomial-coefficients

apr 21 at 2:26 Stopwatch 154

1

12

votes

4

answers

384

views

Relation of this antisymmetric matrix $r = \left(\begin{smallmatrix}0 &1\\-1&0\end{smallmatrix}\right)$ to $i$

linear-algebra matrices reference-request complex-numbers

aug 10 at 0:38 J. M. 38.9k

2

12

votes

2

answers

587

views

$n$ lines cannot divide a plane region into $x$ regions, finding $x$ for $n$

geometry proof-strategy

aug 19 '11 at 0:35 lewist 111

2

10

votes

6

answers

407

views

Evaluate $ \binom{n}{0}+\binom{n}{2}+\binom{n}{4}+\cdots+\binom{n}{2k}+\cdots$

combinatorics binomial-coefficients

feb 21 '12 at 18:33 Peter Tamaroff 25.9k

2

10

votes

3

answers

261

views

Quick way to expand $\cos^{-1}(\cos^2 x)$ up to $O(x^2)$

calculus taylor-expansion

jul 17 '11 at 0:35 Américo Tavares 20.7k

2

9

votes

3

answers

632

views

The vertices of an equilateral triangle are shrinking towards each other

geometry physics analytic-geometry

oct 7 at 16:02 anegligibleperson 651

1

9

votes

2

answers

1

kviews

In a group of 6 people either we have 3 mutual friends or 3 mutual enemies. In a room of n people?

combinatorics pigeonhole-principle

jun 1 '11 at 19:51 JavaMan 8,310

8

votes

3

answers

323

views

Why is closure omitted in some group definitions?

group-theory definition

sep 11 '11 at 23:43 lhf 35.6k

2

8

votes

2

answers

2

kviews

If $f(xy)=f(x)f(y)$ then show that $f(x) = x^t$ for some t

functional-equations

jun 8 '11 at 14:51 André Nicolas 161k

3

7

votes

2

answers

420

views

Math route for someone of this background

soft-question self-learning

oct 7 '11 at 9:07 J. M. 38.9k

7

votes

2

answers

198

views

Largest $k$ for which $a^k +b^k \leq c$

inequality

aug 25 '11 at 14:49 kuch nahi 2,334

1

6

votes

2

answers

234

views

Neglecting higher order terms in expansion

calculus approximation

jun 27 '12 at 12:55 rschwieb 21.1k

1

6

votes

1

answer

371

views

Trying to get the infinite product for $\sin x$

trigonometry

aug 26 '11 at 20:08 André Nicolas 161k

6

votes

1

answer

203

views

Combinatorial Proof: $n! = 1+\sum\limits_{r=1}^{n-1}( r\cdot r!)$

combinatorics

aug 1 '11 at 2:12 J. M. 38.9k

2

6

votes

3

answers

416

views

Best way to set up a wiki for maintaining a structured math journal

soft-question math-software

jul 24 '11 at 8:55 kuch nahi 2,334

6

votes

4

answers

347

views

Modern Equivalent of Carr's Synopsis?

reference-request

may 16 '11 at 9:18 kuch nahi 2,334

5

votes

3

answers

187

views

Intuition behind problem in (classical) algebra

algebra-precalculus

dec 23 '11 at 13:56 Srivatsan 15.6k

5

votes

5

answers

777

views

Proof that cube has 24 rotational symmetries

combinatorics

jun 18 '11 at 15:46 Mark Bennet 9,913

5

votes

3

answers

545

views

Understanding when to use product rule and when to use sum rule?

combinatorics

may 11 '11 at 18:10 Mitch 3,619

1

4

votes

2

answers

843

views

Number of ways of spelling Abracadabra in this grid

combinatorics

apr 8 '12 at 18:04 Braulio 11

4

votes

12

answers

883

views

Prove that $6|2n^3+3n^2+n$

elementary-number-theory divisibility

jan 7 '12 at 17:55 Martin Sleziak 20.3k

4

votes

3

answers

458

views

Understanding direct sum of matrices

linear-algebra matrices

oct 4 '11 at 20:35 Arturo Magidin 158k

1

4

votes

1

answer

112

views

Pairwise prime triples of integers satisfying $x^2+y^2=z^2$

elementary-number-theory

jun 29 '11 at 0:09 kuch nahi 2,334

2

4

votes

1

answer

286

views

When is $\displaystyle \prod_i \prod_j a_{i} a_{j} = \Bigl(\prod_i a_i\Bigr)^2$

products

jun 25 '11 at 19:49 George Lowther 11.5k

kuch nahi

79 Questions