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May
25
comment How many three digit numbers with increasing digits can be formed from the set $\{1, 2, 3, 4, 5, 6, 7, 8\}$?
Care to explain, downvoter?
May
23
comment Finding line that divides an area into equal halves.
The error is when you factor the $\sqrt{1-k}$. More precisely, look at the $(1-k)^{3/2}$.
May
21
comment Finding the period of $f(x) = \sin 2x + \cos 3x$
Yes, that will be it
May
21
comment what will be the value of this integral
At brilliant's, there were absolute value that you missed inside the logarithm
May
19
comment If you fold a rectangular piece of paper in half
What's the solution needing verification?
Mar
17
comment Where do summation formulas come from?
Finite calculus is one way of computing sums cs.purdue.edu/homes/dgleich/publications/…
Feb
26
comment Investigate the convergence of $\int_0^\infty (-1)^\left[{x^2}\right] \, dx$
@AlonAlon because $[x^2]$ is an integer.
Nov
18
comment Are the equations $2x - 2y = 11, x = y - 2$ unsolvable?
This is most likely what was expected from the teacher
Oct
5
comment What is meant by“…on se ramène par régularisation…”?
Careful, "Dénombrable à l'infini" does not mean countably infinite. It is rather linked with a locally compact spaces. I think it means that the space can be written has a countabble compacts family
Sep
23
comment Why is the polynomial $f(x)=x^3+x^2+x+1$ monotonic?
You can upvote all relevant, and accept (and also upvote) the one that suits you best
Sep
22
comment Prove that $f(x)=x^4+8x^3+x^2+2x+5$ is irreducible in $\mathbb Q[x]$
Do you know the rational root test?
May
2
comment Calculating this integral: $I=\int_{0}^{\infty}(\log t)\,(\tan^2t)\,\mathrm{d}t$
You have bounds $0$ and $\infty$ in the title but some other numbers in the body, which is it?
Apr
10
comment Help with this combinatorial proof $\sum\limits_{k=1}^nk^2(k-1){n\choose k}^2 = n^2(n-1){2n-3\choose n-2}$ considering $n\ge2$
Where did you get this formula? left-hand side gives $480$ and right hand side gives $160$ for $n=4$...
Apr
10
comment What does this equal? $6\div 2(1+2)$
how does someone get $7$?
Apr
10
comment Are the two integrals equivalent?
Yes they are indeed the same
Mar
31
comment $f(x)=x$ if $x$ is rational , $f(x)=1-x$ if $x$ is irrational, at what point this function is continuous?
You beat me to it, +1
Feb
26
comment Finding out the coeffcient next to $x^2$ in $(\cdots(x-2)^2-2)^2\cdots-2)^2$.
I don't know why it is, but it seems the recurrence is $a(n)=20a(n-1)-64a(n-2)$, which gives the solution $(4*16^n-4^n)/3.$
Feb
19
comment Prove that $\sum_i\sum_j a_{ij}=\sum_j\sum_i a_{ij}$
See math.stackexchange.com/questions/497096/…
Oct
23
comment Integral of product of two measurable functions
This is essentially a special case of Holder's inequality.
Oct
22
comment Mean value of the image of an exponentiallly distributed time under a smooth curve
$f(t)$ should be $\phi(t)$ in 3.