K.defaoite's user avatar
K.defaoite's user avatar
K.defaoite's user avatar
K.defaoite
  • Member for 6 years
  • Last seen this week
12 votes
Accepted

Solving $\textbf{r}''(t)=\frac{GM}{(r(t))^3}\textbf{r}(t)$

10 votes
Accepted

Evaluating $\sum_{n=1}^{\infty} 1/\phi(n)^2$

9 votes
Accepted

Find the value of $\int_0^1f(x)dx$

8 votes
Accepted

Intuition behind area of ellipse

8 votes
Accepted

Rate of Growth of Permutations of Rubik's Cubes

8 votes

Is the use of the quadratic formula valid? (Flammable Math's "How REAL Men Solve Equations" video)

7 votes
Accepted

Mathematical properties of Rank-$N$ tensors where $N$>2

6 votes
Accepted

2nd order nonlinear ODE

6 votes

Why is $|x|'=\frac{x}{|x|}$?

6 votes

How do I integrate $\frac{1}{x}\frac{d}{dx}\left(x\frac{dy}{dx}+\frac{yx^2}{2}\right)=0$?

6 votes

Are there are any inherent mathematical reasons difficult proofs exist?

5 votes

Compact formula for the $n^\text{th}$ derivative of $\operatorname{sech}^2(x)$?

5 votes
Accepted

Analytic approximation of a series containing Bessel functions

5 votes

Closed form for the hypergeometic function $\,_{4}F_{3}\left(1,-k,k+\frac{3}{2},\frac{1}{2};\frac{1}{2}-k,k+2,\frac{3}{2};1\right)$

5 votes

Does every triangle satisfy $\frac{abc}{R^3} \ln \left(\frac{a}{R}\right)\ln \left(\frac{b}{R}\right)\ln \left(\frac{c}{R}\right) > -\ln 2$?

5 votes
Accepted

Power of a laser beam

5 votes

How can I best improve my understanding on linear operator interactions: $df/dx$ vs $df(x)/dx$, and $df/dx$ vs $dy/dx$, etc?

5 votes

Why $\arctan x$ not equal to $\arcsin(x)/\arccos(x)$?

5 votes
Accepted

Can I reduce fraction under integral?

5 votes
Accepted

How to Evaluate $ \sum_{n=1}^{\infty} \frac{(-1)^n}{n} \sum_{k=1}^{n}\frac{1}{4k-1} $

4 votes
Accepted

I have found a number. Google and OEIS come up blank: 0.696340872970033948754981...

4 votes
Accepted

Why does the negative of the direction of steepest ascent result in the direction of steepest descent?

4 votes
Accepted

$a_{n+1} = \sqrt{2 + a_n}$ Specific Theorem Needed

4 votes

Let $f_{k+1}(x)=f_{k}(\cos x)$ and $f_{1}(x)=\cos x$ then $\lim_{k\to\infty}f_{k}(x)=0.73905\cdots$

4 votes

weird rate problem that I can't solve

4 votes
Accepted

If $a\frac {dy}{dx} + by = c$ has constant coeffcients, does that means that $a=b=c$?

4 votes
Accepted

Can a smooth matrix function $M_{ij}(t)$ change rank?

4 votes
Accepted

Fundamental stress and pressure tensors of the Stokes system in $\mathbb{R}^3$.

4 votes

Calculating the integral $\int_{-\infty}^{\infty} \frac{x^2}{(1 + x^2)^3}dx$

4 votes

Find $\sum_{k=0}^n \frac{1}{(3k+1)(3k-1)}$

1
2 3 4 5
20