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Conreu
  • Member for 2 years, 4 months
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  • Catalunya
5 votes
2 answers
955 views

How to obtain the period of this nonlinear differential equation?

4 votes
2 answers
146 views

Computation of $\left.\dfrac{\text d^{100}}{\text dz^{100}}\cos(z^2)\right|_{z=0}$

3 votes
3 answers
97 views

What's $\int_{-\frac{\pi}{2}}^ {\frac{\pi}{2}}\text{erf}\left(\frac{\sqrt 2 R\cos\theta}{\sigma}\right)\text d\theta$?

3 votes
1 answer
121 views

Computation of electric field related integral, $\displaystyle{\int_0^{2\pi}}\frac{f(\cos x, \sin x)dx}{(A-B\cos x-C\sin x) ^{3/2}}$

3 votes
1 answer
161 views

Change of basis for dual bases

3 votes
2 answers
378 views

Flux of radial vector field through sphere

3 votes
2 answers
125 views

Area of $x^{10}+y^{10}\leq 1$

3 votes
1 answer
96 views

How to compute $\int\frac1x\Bigl(\sum\limits_{n\ge0}\frac{x^{2n}}{2^{2n}(n!)^2}\Bigr)^{-2}\mathrm dx$?

3 votes
0 answers
59 views

Maximize $f(\mathbf n)=\dfrac{N!}{\prod_{j=1}^M n_j!}$ subject to $\sum_{j=1}^M n_j=N$ and $\sum_{j=1}^M e_jn_j=E$

2 votes
1 answer
63 views

What's the product rule for the exponential differential operator?

2 votes
1 answer
42 views

Finding the coefficients of a general solution to an homogeneous ODE via Sturm-Liouville theory

2 votes
2 answers
76 views

Power series solution to $x^2y''+y'+y=0$ around $x=0$

2 votes
1 answer
120 views

Evaluation or simplification of $\displaystyle{\int_0^{\frac{\pi}{4}}}\dfrac{dx}{\sqrt{A-\cos x-Bx}}$

2 votes
1 answer
113 views

How to integrate $\int x'(t)\ dx(t)$ and similar?

2 votes
2 answers
127 views

How can I solve a differential equation of the form $c_1 \ddot{x}^2 + c_2 \ddot{x} + c_3 \dot{x}^2-c_4 =0$?

2 votes
2 answers
87 views

Solving $x^2y''+2xy'+2y=0$ using power series

2 votes
1 answer
178 views

Contour integral of $\sqrt{\frac{z}{z-1}}$

2 votes
1 answer
83 views

Conservation of swept area (Kepler's $2$nd law), rigorous proof

2 votes
1 answer
62 views

Find parameters such that $f(z)=\log(x^2+y^2)-a(\arg z)^2+ib\arg\bar z+\dfrac{c}{\bar z}$ is analytic

1 vote
0 answers
38 views

Branch cuts of $\log(z^2-1)$ for unusual principal values

1 vote
1 answer
59 views

Is it possible to find $\sum_{k=1}^nkr_k$ if $\sum_{k=1}^nr_k=N$?

1 vote
1 answer
99 views

How to solve the differential equation of the form $a\ddot{x}-f(t)\dot{x}^{-1}+b \dot{x}^2+c=0$?

1 vote
1 answer
82 views

How to solve $\ddot{x}=c_1 \dot{x}^2-c_2 x^{-2}$?

1 vote
1 answer
193 views

How to find equilibrium points of this differential equation

1 vote
0 answers
45 views

How can I solve $\sin{\xi \Psi}-\zeta \frac{\cos{\xi \Psi}}{\cos{\Psi}}=0$ using perturbation theory?

1 vote
0 answers
81 views

Number of possible ways to arrange particles in space

1 vote
2 answers
81 views

Probability of survival without rolling chamber (russian roulette)

1 vote
1 answer
93 views

Chain rule applied on Jacobian

1 vote
1 answer
58 views

How to prove $\displaystyle f(n,k;p)=\frac{1}{2\pi i}\oint_{|z|=1}\dfrac{(pz+1-p)^n}{z^{k+1}}\,\mathrm dz={n\choose k}p^k(1-p)^{n-k}$?

0 votes
0 answers
30 views

How to tackle the Laplace Transform of the $n$th derivative if we don't know $f^{(k)}(0)$ from boundary conditions?