user avatar
user avatar
user avatar
P.K.
  • Member for 10 years
  • Last seen this week
56 votes
17 answers
6k views

What is $-i$ exactly?

50 votes
7 answers
3k views

Computing $999,999\cdot 222,222 + 333,333\cdot 333,334$ by hand.

35 votes
2 answers
1k views

$n$ people sitting on a circular table without repeating neighbour-sets

20 votes
4 answers
3k views

Why dividing by zero still works

14 votes
7 answers
4k views

Is a counterexample considered a rigorous proof that a property is not true?

12 votes
4 answers
2k views

Prove that $x = 2$ is the unique solution to $3^x + 4^x = 5^x$ where $x \in \mathbb{R}$ [duplicate]

8 votes
5 answers
4k views

What exactly is "approximation"?

7 votes
6 answers
2k views

How to simplify $\frac{4 + 2\sqrt6}{\sqrt{5 + 2\sqrt{6}}}$?

4 votes
3 answers
2k views

Summation of a finite series involving permutations.

3 votes
1 answer
1k views

$\cot\theta + \tan \theta = x$ and $\sec \theta - \cos \theta = y$, evaluate $\left(x^2 y + xy^2\right)^{2/3}$

2 votes
1 answer
351 views

Prove that $\rm area(\triangle ABE) = area (ABCD)$ [duplicate]

2 votes
3 answers
143 views

$x = \sqrt[3]{3} + \frac{1}{\sqrt[3]{3}}$, what is $3x^3 - 9x$?

2 votes
2 answers
131 views

Factoring a long expression in the form $(a+b)^3 + (c - b)^3 - (c+b)^3$

2 votes
1 answer
248 views

The G.C.D of two numbers is $23$. The other two factors of the L.C.M are $13$ and $14$.

1 vote
2 answers
79 views

Polynomial Rewriting Proof

0 votes
5 answers
547 views

How can I algebraically prove that $2^n - 1$ is not always prime?

0 votes
1 answer
50 views

Number of four-term GPs consisting of positive integers under 100: how to write a program