Mar
20
comment Basic Math Question equation to equal 21
$6/(1-5/7)$ You have use parantheses. There is no way if you do not use parantheses.
Mar
8
comment How can you measure out six liters of water?
based on the idea of @Kaladin: fill the 9 liter buckte and remove 2 time 4 liter with the 4 liter bucket then 1 liter remains. put this in the tube. so you can fill the tube win an arbitrary integer number of liters
Mar
8
comment Do we need to formally teach the Greek Alphabet?
@Carl Mummert: t was talking about the 20th century. I have the impression that this alphabet is not used often today ( I would have some explanation for this). But maybe my observation is wrong.
Mar
7
comment Limit, 0/0, square roots
My advice did not work :-(
Mar
7
comment Limit, 0/0, square roots
I would try $$1-y^3=(1-y)(1+y+y^2)$$ to make the denominator rational. Take $y=\sqrt[3]{5-x}$
Mar
5
comment Approximating 'big' ratio with 'small' ratio
as other stated you should use continuous fractions. continous fraction will find $\frac{1}{3}$ and $\frac{3}{7}$
Mar
5
comment Approximating 'big' ratio with 'small' ratio
so for a given $\alpha=\frac{m}{n}$ and $v \in \mathbb{N}$ you want to find the minimal $q \in \mathbb{N}$ such that there is a $p \in \mathbb{N}$ that $$|\alpha - \frac{p}{q}| \lt 10^{-v}$$ Is this right?
Feb
27
comment $x^2-1$ with prime factors < 100
I think this is this paper: math.leidenuniv.nl/~fnajman/FLFNMC.pdf
Feb
23
comment Can subsequences be finite?
-1 $a_1, a_2, a_3, a_3, a_3, \cdots$ is not a subsequene
Feb
22
comment An equation, where the solution does not exist, but on solving the equation we got a solution. why this is happening?
process your solution procedure in reverse order: substitute your solution for x in the equation. when it first hapens that it is not a solution then figure out what happened
Feb
19
comment $\angle ABD=38°, \angle DBC=46°, \angle BCA=22°, \angle ACD=48°,$ then find $\angle BDA$
Is there a precise definition for elementary geometry? Congruent triangle , compass and ruler constructions, what else?
Feb
19
comment $f(f(x))=f(x)$ question
@fatmattxle yes
Feb
19
comment $f(f(x))=f(x)$ question
$f(x)=0,x \in \mathbb{Q}$, else $f(x)=\pi$. is a function that is not continous and has this property
Feb
19
comment $f(f(x))=f(x)$ question
Combine some of these three: $f(x)=x,x>0$, $f(x)=const, x<0$
Feb
17
comment Grandi's series contradiction
no, it is not a contradicition. closed under addition means that any finite sum of integer is an integer. Are you talking about finite sums of integers? What are you talking about? It is a contradiction of you say $S=0$ and $S=1$ because the numbers $0$ and $1$ are different in $\mathbb{Z}$
Feb
17
comment Regions in $\mathbb{C}$ containing rectangles
@5xum No, if $\Omega$ is the rectangle $1,i,-1,-1$ an the right triangle is $0.9, 0, 0.9i$ the 4th vertex is $0.9+0.9i$ which is not in $\Omega$
Feb
17
comment Regions in $\mathbb{C}$ containing rectangles
@Marcin Łoś No, if $\Omega$ is the rectangle $1,i,-1,-1$ an the right triangle is $0.9, 0, 0.9i$ the 4th vertex is $0.9+0.9i$ which is not in $\Omega$
Feb
17
comment Regions in $\mathbb{C}$ containing rectangles
So it is not necessary for $\Omega$ to be connected?
Feb
16
comment probability $2/4$ vs $3/6$
@Thomas Ahle is the question unintuitive or the answer?
Feb
16
comment Tricks. If $\{x_n\}$ converges, then Cesaro Mean converges (S.A. pp 50 2.3.11)
What is the meaning of S.A. int the title?