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Alec
  • Member for 8 years, 7 months
  • Last seen more than a week ago
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62 votes
17 answers
9k views

Which is larger? $20!$ or $2^{40}$?

8 votes
5 answers
439 views

Evaluating $\int\limits_0^\infty \frac{e^x}{1+e^{2x}}\mathrm dx$, alternate methods

8 votes
2 answers
2k views

If a function is continuous everywhere, but undefined at one point, is it still continuous?

7 votes
2 answers
136 views

Integrating $\frac{1}{(1-x)^2} $ into two different-looking functions

6 votes
4 answers
417 views

Optimal route consisting of rowing then walking

6 votes
5 answers
550 views

Calculating $\sum\limits_{n=1}^{\infty}\frac{(-1)^n \sin(n)}{n}$

5 votes
2 answers
2k views

Why is the implication "If pigs could fly, I'd be king" a true implication? [duplicate]

5 votes
2 answers
207 views

Last digit of $235!^{69}$

5 votes
2 answers
2k views

Making a piecewise function continuous and differentiable at point

4 votes
1 answer
325 views

Showing that any group of order 286331153 is abelian

4 votes
0 answers
217 views

Geometry puzzle - Show that $x = y$ [closed]

4 votes
2 answers
1k views

How to determine if an equation is algebraically solvable?

4 votes
4 answers
2k views

Show $\ln2 = \sum_\limits{n=1}^\infty\frac1{n2^n}$

4 votes
1 answer
153 views

Proving continuity for $2x+1$ at $x=2$ using epsilon/delta

3 votes
2 answers
518 views

For a primitive pythagorean triple $(a, b, c)$, prove $(c+b), (c-b)$ are both squares.

3 votes
4 answers
123 views

$25! \pmod {78125}$

3 votes
1 answer
51 views

Partitions of $\mathbb Z$

3 votes
1 answer
195 views

Integral test to show that $\sum_{n=2}^{\infty}\frac1{n(\ln(n))^p}$ converges for $p>1$ and diverges otherwise.

3 votes
3 answers
127 views

Not defining the imaginary number $i$ as the principal square root of $-1$.

3 votes
5 answers
257 views

Determine con-/divergence of $\sum\limits_{n=1}^{\infty}\frac{1+2+\cdots+n}{2^n}$

3 votes
3 answers
151 views

How many of the numbers in $A=\{1!,2!,...,2015!\}$ are square numbers?

3 votes
1 answer
137 views

Using $\sqrt{1-t}\leq 1-\frac t2$ to show that $\frac{1\cdot3\cdot5\cdots(2n-1)}{2\cdot4\cdot6\cdots2n}\geq\frac1{2\sqrt n}$

3 votes
1 answer
2k views

Mathematical XOR

3 votes
2 answers
3k views

Finding equation for conic section given five points

3 votes
4 answers
62 views

Given $\vec r(t)$, what are $\vec v(t), \ v(t), \ \vec a(t), \ a(t)$?

2 votes
1 answer
165 views

Determining conic section equation given foci and sum of distance to each point

2 votes
2 answers
1k views

How does the eccentricity of a conic section define its shape?

2 votes
1 answer
3k views

Parameterizing an ellipse

2 votes
4 answers
6k views

Proving by calculation that $\arg(-2) = \pi$

2 votes
1 answer
71 views

Existence of limit when encountering $\frac00$

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