K.defaoite's user avatar
K.defaoite's user avatar
K.defaoite's user avatar
K.defaoite
  • Member for 4 years, 5 months
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10 votes
Accepted

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

10 votes
Accepted

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

8 votes

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

8 votes
Accepted

Intuition behind area of ellipse

8 votes
Accepted

Rate of Growth of Permutations of Rubik's Cubes

6 votes
Accepted

2nd order nonlinear ODE

6 votes

Are there are any inherent mathematical reasons some proofs are difficult?

6 votes

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

5 votes
Accepted

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

5 votes
Accepted

Can I reduce fraction under integral?

5 votes

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

5 votes

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

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?

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
Accepted

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

4 votes
Accepted

Finding out the perimeter of the ellipse?

4 votes
Accepted

If $\bf L$ is constant in time why can we write ${\bf L} \times \frac{d\bf{p}}{dt}=\frac{d}{dt}\left({\bf L} \times {\bf p}\right)$?

4 votes
Accepted

How come, in the heat equation, the maximum can not be attained on the upper boundary of the rectangle we construct?

4 votes

Is there a way to get the Fourier transform / series of sinc(a*cos(t))?

4 votes

Integrating from $\int_0^\infty \frac{\sin(x)}x dx$ with year 10 mathematics?

4 votes

How should we define $E \subset F$?

4 votes

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

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 $a=b=c$?

3 votes

Tetrahedron circumradius in high dimensions

3 votes

Finding the limit of $a_n = \frac{n+1}{2^{n+1}}\left(\frac{2}{1}+\frac{2^2}{2}+...+\frac{2^{n}}{n}\right)$

3 votes

$\sin(3x)/2x$ to power series?

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