User user85798 - Mathematics Stack Exchange

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user85798

Member for 10 years, 4 months
Last seen more than 5 years ago

90 Answers

Score Activity Newest

87 votes

Accepted

Why is $(2+\sqrt{3})^{50}$ so close to an integer?

answered Nov 11, 2013 at 17:20

80 votes

Rules for Product and Summation Notation

answered Nov 4, 2013 at 10:45

30 votes

Accepted

When written in decimal notation, every square number has at most 1000 digits that are not 0 or 1. True or false?

answered Nov 2, 2013 at 5:46

20 votes

Find the Area of the ellipse

answered Nov 2, 2013 at 10:57

16 votes

Why can't you square both sides of an equation?

answered Nov 16, 2013 at 1:13

15 votes

Why $\sum_{k=1}^{\infty} \frac{k}{2^k} = 2$?

answered Nov 24, 2013 at 4:07

12 votes

I need help finding integral of $\frac{1}{x^2+x^4}$

answered Nov 28, 2013 at 12:39

12 votes

Interesting but short math papers?

answered May 21, 2014 at 2:09

11 votes

Which is greater, $e^{\pi}$ or $\pi^e$?

answered Jun 18, 2014 at 20:10

10 votes

How to determine countability of $\Bbb N \times \Bbb N \times \Bbb N$?

answered Nov 17, 2013 at 3:56

9 votes

Show that $\sum_{n=0}^\infty r^n e^{i n \theta} = \frac{1- r\cos(\theta)+i r \sin(\theta)}{1+r^2-2r\cos(\theta)}$

answered Nov 1, 2013 at 17:40

8 votes

Accepted

Evaluate $\int_0^e{W(x)}\,\mathrm{d}x$

answered Nov 4, 2013 at 7:18

7 votes

Infinite Product $\prod\limits_{k=1}^\infty\left({1-\frac{x^2}{k^2\pi^2}}\right)$

answered May 13, 2014 at 0:31

6 votes

Proof of divergence of $1/2 + 1/3 + 1/5 + 1/7 + 1/11 +....$

answered Nov 15, 2013 at 3:03

6 votes

Accepted

Proof by induction that fibonacci sequence are coprime

answered Nov 13, 2013 at 13:31

6 votes

Accepted

Cantor's Theorem for $\Bbb N$.

answered Nov 3, 2013 at 11:48

6 votes

Double Angle Formula?

answered Mar 10, 2014 at 21:51

5 votes

Accepted

Integrate $\int \frac{\sin^2(x)}{1+\sin^2(x)}dx$

answered May 17, 2014 at 20:07

4 votes

Accepted

Prove that $4x(x-5)^3 + (x-5)^4=5(x-5)^3(x-1)$

answered Mar 22, 2014 at 18:28

4 votes

Evaluate the integral: $\int\tan^5 (4x)\,\mathrm dx$.

answered Mar 22, 2014 at 19:28

4 votes

How is $f_{2000}$ equals $0$?

answered Apr 9, 2014 at 11:32

4 votes

Accepted

How to find $ \sum\limits_{n=0}^{\infty}\frac{1}{3-8n-16n^2}$?

answered Nov 18, 2013 at 2:14

4 votes

Proving $4(a^3 + b^3) \ge (a + b)^3$ and $9(a^3 + b^3 + c^3) \ge (a + b + c)^3$

answered Dec 6, 2013 at 23:56

4 votes

Compute $\int_0^{1/2} (\arcsin(x))^2 dx$

answered Nov 2, 2013 at 12:26

4 votes

Accepted

Why $\arctan x \to \pi/2$ when $x \to \infty$

answered Nov 3, 2013 at 18:15

3 votes

Proving -(a+b) = (-a) + (-b) using A1-A4 only.

answered Nov 2, 2013 at 15:29

3 votes

Accepted

Arithmetic and Geometric progression question

answered Dec 6, 2013 at 14:06

3 votes

How can I solve $\sin(x)=\sin(2x)$?

answered Jan 19, 2014 at 1:52

3 votes

evaluate $ \int \frac{4x^5-1}{(x^5+x+1)^2}dx$

answered Mar 12, 2014 at 20:29

3 votes

How does $\mathrm {e}^z$ and $\log z$ look like as complex functions.

answered Nov 22, 2013 at 20:39

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