Reputation
1,262
Top tag
Next privilege 2,000 Rep.
Edit questions and answers
Badges
2 7 21
Newest
 Yearling
Impact
~5k people reached

Apr
19
comment Do we have $\sum_{n=1}^\infty 0=0$?
Then this is completely different sums.
Mar
12
comment Sign of a solution for an ODE
There is a multiplication by constant in the first one, you can simply hide $\pm$ in there.
Oct
27
comment generalization of geometric series $ \sum_{k=0}^\infty x^{p(k)} $
It's impossible to find for arbitrary polynomial, but for some particular it's possible to find a closed forms. Probably in some elliptic theta functions.
Sep
14
comment Does the following integral converge: $\int_6^{\infty}\frac{dx}{\sqrt{1+x^2}}$
Why won't you just evaluate it?
Sep
13
comment Analysis of the function $y=x^{\frac{1}{x}}$
@ClaudeLeibovici I plotted $\Im x^{1/x}$ in Mathematica, it's not zero for $(-1,0)$.
Sep
13
comment Analysis of the function $y=x^{\frac{1}{x}}$
It's complex valued for $x\le0$.
Sep
7
comment Recurrence relation of the following sequence?
It's simply only the $a_n = \lceil\frac{n}{2}\rceil$. Why even-odd?
Aug
26
comment How to prove $\int^{\pi/2}_0 \log{\cos{x}} \, \mathrm{d}x = \pi/2 \log{1/2}$
@idm this can be easily integrated by parts.
Aug
25
comment How do I integrate $\frac{\sqrt{1-k^2\sin^2 x}}{\sin x}$
@Jean-ClaudeArbaut Thanks for this reference. Why'd in physics I didn't encounter the one's, that can be expressed with elementary functions?
Aug
25
comment How do I integrate $\frac{\sqrt{1-k^2\sin^2 x}}{\sin x}$
@Jean-ClaudeArbaut Maybe, as a physicist mine elliptic integrals are one, two, three complete/incomplete integrals.
Aug
25
comment How do I integrate $\frac{\sqrt{1-k^2\sin^2 x}}{\sin x}$
@Jean-ClaudeArbaut It's definitely not an elliptic integral. It's actually can be expressed as a primitive functions.
Aug
24
comment Quotient rule, one sign wrong
@Paul Nope, you are correct, and the book answer is wrong.
Aug
24
comment Why is the result of $-2^2 = -4$ but $(-2)^2 =4$?
Because first one is $-(2^2) = -(2\cdot 2) = -4$ and the second one is $(-2)^2 = (-2)\cdot(-2) = 4$?
Aug
23
comment How to solve this linear system using determinants and using matrices
Move the $3y$ to the LHS in that equation... and be happy!
Aug
22
comment How to find $\int \frac{x^4-4}{x^2\sqrt{4+x^2+x^4}} \,\mathrm dx$
@Aditya and what is the solution in textbook?
Aug
22
comment What is the concept behind …?
Concept of vector calculus.
Aug
22
comment Integral of inverse of square root of a quadratic
@Starior Because there are infinitely, but uncountable set of rings; and sum can only been used on a countable set of rings.
Aug
21
comment calculus / algebra
Is this from some physics textbook? Share the context.
Aug
21
comment Integral of inverse of square root of a quadratic
@Starior Yes. I used $+\delta$.
Aug
21
comment Integral of inverse of square root of a quadratic
@Starior I used the cylindric coordinates, where $z$ is a line of symmetric of this rings.