#help-33
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@obtuse sky Has your question been resolved?
okay so whats the question?
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how do i prove pascal's theorem using menelaus?
try to prove that (GZ/GX)(IX/IY)(HY/HZ)=1
@cunning oak
use Melenaus repeatedly in triangle XYZ and the lines that cut through it
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need help in likelihood ratio
why there are two different formula here
i thought likelihood is produkt of the funktions under null hypothese divided byprodukt of the funktions under alternativ hypothese
They probably mean the same thing
@limpid zealot Has your question been resolved?
I presume somewhere in your text it will define what these symbols means
They are probably defined to be the same thing
Seems like i skipped the part.
But isnt likelihood is product of the functions on all xi s
Thats why check the definition
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Where to start?
start with smaller cases
smaller observations
like three matches
instead of '5'
and observe patterms
patterns*
A game ends when a player wins 5 matches. There are two players and a match can only end in win or loss. In how many ways can the game end?
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Hi. I am trying to work part b
. What I got are these: 20/36 = 5/9 - at least 2 of the scores are greater than 4, 18/36 = 1/2) for the sum of the two scores being odd and 6/36 = 1/6 for two scores being equal
I was getting assistance earlier but I didn't complete it
I have a question for the solution
I was told this and I agree -->since the dice are independent, the probability of both being <= 4 is (2/3)x(2/3) is 4/9 ....2/3 because 1,2,3,4 are 4 options out of 6... so 4/6 simpliefied is 2/3
Then I believe I should subtract it from 1
My question is, why can't I just do 2/6 * 2/6 --> Seeing you only can get a 5 or a 6?
It's a little hard to follow what you write out
This part or everything?
First part
Independence is an iff statement: P(A) * P(B) = P(A and B). You can just evaluate both sides.
Which two events are you considering to possibly be independent here? M and W?
What's P(F)?
18/36 = 1/2
P(M) = 20/36 = 5/9
I get to multiply it and I get 5/18
but how do I know the intersection?
P(F n M)
Do I have to count it?
I would count it, I don't see any shortcut here. Of the 20 outcomes of M, how many are also F
Ah, I didn't count it
I mean there's some amount of hand-wavey symmetry here, but I'm not sure if it can be easily shown rigorously (and tbh trying to do so would probably take more time than couting 20 events)
And (6,1), (5,2), ... right?
Yeah, don't you count them in the 20 events where at least one of the dice are over 4?
Yeahh
because I realize that the numerator is 5 but I forgot that the answer was cancelled for it to be 5
5/18
let me continue
yeah, 10/36 is what reduced to that
Yup those are the 10 events where one die is over 4 and where the sum is odd
Of the 36 possible outcomes of two die rolls, P(F and M) = 10/36 = 5/18
This part
I don't understand the easier method to get the20/36 without counting
P(M)
at least one of the two scores is greater than 4
I think I got the 1 - (4/6 * 4/6)
but what if I was focusing on the 2 outcomes for it to be more than 4
Why can't it be 2/3 * 2/3
sORRY
2/6 * 2/6
The outcome of two dice rolls are independent, we can agree on that right? One die being above/below 4 has no bearing on whether or not the second die is above 4
Yes, independent
Our "winning" event is both being above 4. Let D1 be the probability that the first die is above 4 and D2 be the probability that the second is above 4. P(D1 or D2) = -P(D1 and D2) + P(D1) + P(D2) = -(1/3)^2 + 1/3 + 1/3 = 5/9
Recall inclusion/exclusion
Ok, let me read through
This is the same thing, but you find the complement of winning (losing) and subtract 1 - P(losing). Feel free to do this as an exercise to confirm you get the same result if you want.
Alrighty, sure
I have to run now. I should be back in a few, hopefully because I have more questions to do. I got to go and come back
Thank you so much
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np
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are they using the fact that the cyclic group generated by a is the smaller subgroup containing a in this proof to say <a^k> is a subset of <a^d> and the converse?
For example if a^d = (a^k)^t then since <a^d> is the smallest subgroup containing a^d and <a^k> also contains d, that means <a^k> contains <a^d>
Im just wondering if im reasoning about this right because they dont really explicitly say why its a subset of the the other unles im missing something
Sure, that works
you can kind of have 2 definitions for the subgroup generated by S, one of them is this, and the other is ${s_1s_2\ldots *s_n|s_1,\ldots,s_n \in S}$
Dreyuk
(for cyclic groups this can be made a bit simpler lol)
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Having trouble understand this second part
What tells us |a^d| = n/d? How do we know that this is the smallest possible intger such that a^d = e?
also I think theres a typo in the last sentence, do I ignore the expression before the last equal sign
oh wait
so they say that implies the |a^d| <= n/d
so I assume the next sentence shows that |a^d| >= n/d but I dont see it yet so ill try taking another look
ok I see
because the order of a is n
and i is less than n/d
so theres no ways to multiply n/d by i such that n/d = n
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i dont really understand the solution given for b, ii
(the cards are selected with replacement)
Why are we doing 4 * 4 * (1/4)^3
i think one of the fours is extraneous
they meant only 4 * (1/4)^3
this in fact lines up with the stated answer of 1/16
oh okay lol i was so confused
typo, really
yes
okay!, in this case the fact that its a geometric distribution is useless correct?
like for this specific question atleast
this fact is just useful for the other questions (A and B i)
thanks ann (again :p) :}
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X is not even involved here
ah yea, brain is kind of turned off after a full day of doing this i guess lol 
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how do i do this
What have u tried
tried using synthetic but saw that there's 2 diff variables so dk what to do next
@zealous plume Has your question been resolved?
!showwork
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I don't know how to start
Do u know the formulas of S.I and C.I
Alr now express them in ratio form
Also note that the r/100 represents percentage
That is if u r given r= 2% ,in place of r u will need to place 2
And in case of C.I ,if r is 2 %
Then in place of r u need to write 0.02
So it's better to express the r of S.I as r itself
$\frac{P(1+r)^n}{Prn}=\frac{169}{144}$
Victimizer
Yes
Cross multiply first
There is a mistake
Compound interest is P(1+r)^n -P
So it should be
$\frac{P(1+r)^n-P}{Prn}=\frac{169}{144}$
Victimizer
And then
$\frac{P((1+r)^{2}-1)}{Pr2}=\frac{169}{144}$
Victimizer
$\frac{((1+r)^{2}-1)}{2r}=\frac{169}{144}$
Victimizer
$\frac{(1+2r+r^{2}-1)}{2r}=\frac{169}{144}$
Victimizer
$\frac{2r+r^{2}}{2r}=\frac{169}{144}$
Victimizer
$\frac{r(2+r)}{2r}=\frac{169}{144}$
Victimizer
$\frac{(2+r)}{2}=\frac{169}{144}$
Victimizer
U think u can solve from here? @shy mica
it becomes little lengthy
But solvable
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can someone please explain how mutual exclusion does not work here? since P1 has already set the lock variable as 1 (even before pre-emption), how is P2 able to enter the critical section?
it seems to me like just P1 is paused just before updating the lock and after checking if the lock is valid
so P2 can also enter the lock in the small amount of time the lock is still not locked
p1 gets preempted after changing the value of lock variable from 0 to 1, before entering the critical section
I see a meanwhile
no, wait, it enters the critical section and then gets preempted
but it never sets the value back to 0, no?
but its preempted before updating the lock to 1
thats what I think they meant
what context is this paragraph?
eh, how is it entering the critical section though, then?
lock variable in process synchronization
that 'meanwhile' is doing a lot of work here
yes
it just sounds poorly written
I don't see any other interpertation that makes sense
yes indeed
other then that the locking and validating the lock is not done atomically
i do not quite follow
to prevent this, we would want to be able to check if the lock is unlocked and lock it at the same time
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this is usually done by the CPU btw
just some instruction
.reopen
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i think what i do not get is
say p1 wants to get executed
at beginning, the lock is set to 0
so it does not enter the while loop and then sets the lock to 1
and enters the critical section
but then, it gets preempted
now, p2 wants to start its execution
the paragraph says that it will be able to enter the critical section too because the lock is set to 0, but, that is not true? because p1 never updated the value?
like I said
I think they meant that p2 is trying to enter the critical section just before p1 updates the lock to 1
and that aquiring the lock is not atomic
and it should be atomic
P1: While (lock != 0)
P2: While (lock != 0)
P2: Lock = 1
P1: Lock = 1
P2: //Critical Section
P1: //Critical Section
Whoops
well, that makes sense
this probably sounds stupid but, is that not done before a process enters the critical section? how is that relevant here?
I meant the same as Xwtek
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i see. so if i understand this correctly, the main problem with this algorithm is that both p1 and p2 can see the value of lock variable (0) at the same time and hence both can enter the critical section simultaneously?
Yup.
yes
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Confused on if I can just equal it to x-1/x-1 or how to split it into a piece wise function
|x| = x
for positive x
Yeah, and both left and right hand limits are positive
So can I just use positive c
X*
yeh
weird how?
but you don't really care about the value at x=1
you're more concerned about what happens around that
I see, so the value doesn’t exist
But the limit does
For showing my work, is this fine
cancel the whole x-1 ,
it looks like your cancellation is just on the x
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I'm having a bit of trouble trying to figure out what boxes to check off! If someone could help guide me through it that would be great.
The question for it
What have you tried?
If anything
Well, I didn't try anything yet because the question was a bit complex for me to understand
Did your teacher teach inverse functions yet?
We switch x and y right
Okay
What is the simple rule in the table
Just look at it and see the pattern
Between f^-1(x) and x
Actually
This is probably more efficient
Since we already have a table from x to f(x)
If you wanted to find it without the x->f(x) table it would require using the inverse
@opal raptor Has your question been resolved?
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i need help understanding how to do this
Can u find the line y=-1 first
Mark it up
what
The line y=-1
yse
When a point is reflected over a line , the distance between its coordinate and the line & the distance between its reflection point and the line is equal
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Pardon me, does anyone here do statistic math?
I am learning the Understand principles of Chebyshev's Theorem
Basically I dont understand the theorem at all
(please ping me when someone is available)
I can just give you the general concept, im not that versed on statistics
Um yes please yeah
What exactly is it?
And if so do you know someone that is versed on statistics
Ill assume you know what the normal distribution is
If so, you probably can remember that its usually taught that ~68% of the data is within a standard deviation of the mean.
~95% for 2 deviations
~99.3% for 3 deviations
Well, the Theorem states a similar concept but for any dataset. Specifically, it sets a lower bound for the data found based on the amount of "standard deviations" you distance yourself from the mean.
@celest stream Has your question been resolved?
Very interesting
tysm
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guys srry for ask easy math problems but what is the result from this 6 + 6/7
rewrite 6 with the denominator being 7 first
then simply add the numerators and your done
Yooo can someone help me ?
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need help
yeah
- im having trouble understanding how and why our components turned into equations like that, even though they are vector components
it just doesnt make sense to me how all of sudden those components because equations to graph a line
Direction vector $\vec{v}$ is parallel to $\overrightarrow{PP_{1}}$ but there's nothing to ensure they're equal but we do know we can find a number t that when we do scalar product we get $t\vec{v}=\overrightarrow{PP_{1}}$
Alexis_Fx
right i agree
so you are saying a constant t will scale the direction vector to make it equal to our line
but i just dont understand why and how that magically turns into equations
that graph our line
i need help understanding how the vector components went from vector components to equations of a line
v<a,b,x>
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ok
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Create a two-column proof.
<@&286206848099549185>
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Chill
sorry
i think that's just the definition of trisecting an angle
What's the definition of trisect that you've learnt
"2 points (or segments, rays, or lines) that divide a segment into 3 congruent segments bisect the segment. The 2 points at which the segment is divided are called the trisection points."
to reword the question its saying given angle aeb which is congruent to angle bec which is congruent to angle ced, prove that rays eb and ec trisect angle aed using a two-column proof
whats cis(x)
it's a way of writing complex numbers
thats sooo trivial bruh
how is it pronounces
pronounce*
bruh
ok pls move to chill, you two
its that "great part of geometry" according to my teacher
wdym
if we aren't spamming two column proofs, we are spamming paragraph proofs
shes obsessed with two-column proofs
So at what point are we planning to start helping
Okay genuinely, what even is there to prove here
if this channel is not occupied anymore lemme know
idk 😭
Just get a different channel
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say less
?
as in i have the channel now
i hate geo 💔
.close please
facts
wait how do i close it again
type .close
.close
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👍
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There are 4 marbles A,B,C,D,we have to arrange it in a order such that A and B shd not be beside each other,ik the answer is 12 and it is 4! - 3!
4! is the total combination,what is 3!\
4! - 3! = 18
do you know complementry counting
ik combinotorics,no
How many options are there for ordering the marbles without the restriction?
basicly its where you take the total outcomes and subtract the ones that aren't the right ones
4x3x2x1
yes
ic
Now how much did you overcount?
how do i find it?
hmm
please explain,i will get the idea of solving these type of questions
yeah I am tired give me one sec
ok
there is a better way
which is
since you want A,B to be together we can think of them as one marble
and then order the C,D and AB
3! is the cases where A,B are together
and then order AB internally
is 4! -3! right answer tho,isnt it 12
so we get 3!?
oh its should not be beside each other
3! * 2!
its 18
why so
You would need to arrange A,B too
A,B and B,A
That is the 2!
So 4!-3!*2!=12
There is another way to do this idk if you guys wanna listen
so we have two ways to arrange one is AB,and the other is BA,for each case there is 6 wrong,so it 6x2=12, 24 -12 = 12
thanks
sure
Ok we know without restrictions is 4! Right
ye
Here
He's talking about P(n,r)
3P2 is not the same as 3!
No, not C(n,r) that's a different thing...
I use nPr and nCr
what does nPr do?
The relation between C(n,r) and P(n,r) is:
C(n,r) * r!= P(n,r)
Number of premutations
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for calc 3, no clue where to start
well do you know how to find an orthogonal vector to w?
cross product?
you can either find some orthogonal vector and then solve a system, or easier would be to find the projection of v onto w
do you know how to find the projection of v onto w?
no
hmmm are you aware of dot products
yes
we use those to find projections
what is a projection
a projection is something youre familiar with, you just havent heard of the technical term probably
in this art work, Vx is the projection of V on the x-axis and Vy is the projection of V on the y-axis
the thought process of using projections is basically this: you find the projection of V onto w, which is by definition parallel to W, and then the difference between V and V(proj.w) is the perpendicular part
okay so how do i find the projection
the projection of vector A onto vector B is just a⋅b/b⋅b *b
so in your case, you can just do (v⋅w/w⋅w)*w
and youll find your projection
yep
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Trying to prove a dual basis defined $\beta^={\alpha^1,...,\alpha^n}$ is a basis of $V^$ over $\mathbb{F}$, but I'm stuck on span. I've got that $\forall\phi\in V^*$ we need some $c_1, ..., c_n\in\mathbb{F}$ so that $\phi(v)=\sum_{i=1}^{n}c_i\cdot\alpha^i(v)$ and that $\alpha^i(v)=d_i$ for any $v=\sum_{i=1}^n d_i e_i\in V$, but after/apart from that im stuck. any guidance wld be nice
Syrenate
oh idk if any of this is standard but $\alpha^i$ is defined by $\alpha^i(e_j)=\delta_j^i$ where $\beta={e_1,...,e_n}$ is a basis of $V$.
Syrenate
could you send the original question?
thanks
to obtain the various $c_i$, evaluate $\phi$ at each $e_i$
soup_norm
why?
for now, try it and see what happens
assuming $\beta^*$ is a basis?
Syrenate
dont see how else I can
wait let me think of a better hint
show that for all $v \in V$,
[ \phi(v) = \sum_{i = 1}^n \phi(e_i) \cdot \alpha^i(v) ]
soup_norm
and this will suffice
i can see how that suffices because $\phi(e_i)$ is well defined in $\mathbb{F}$ but i really cant see how youd get to that form
You can express v in terms of the basis of V
Syrenate
sure, $v=\sum_{i=1}^n c_i e_i$, gives that $\alpha^i(v)=\sum_{j=1}^n c_j\cdot\delta_j^i = c_i$
Syrenate
Yes
(I’m going to not elaborate until you ask because you might be able to figure it out from here)
i already had that result before i came here could u pls elaborate
Ok
Consider: $\phi(v) = \phi\left(\sum_{i=1}^n c_i e_i\right)$, then expand by linearity and use the equation you sent
soup_norm
linear and abstract?
i mean its using linear algebra
oh
itd better be anyway
better not be studying this for no reason
back to it!
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help me pls what is cosa ?
@everyone
that doesn’t work bud
Also, even if it did
you wait fifteen minutes before pinging helpers
goes to server with 300k+ members
tries to PING EVERYONE
i understand
anyway have you tried working out some other angles here in terms of alpha
I tried
haha
there's no real need to determine unmarked lengths
did you determine any other angles in terms of alpha as Ann asked?
@odd rivet Has your question been resolved?
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Hi can someone please tell me how I can solve this? I can't get past trying to simplify the expression 😭
*more context, I'm using u-substitution to solve it, letting u=tan(x)
well.first
you xan simplify the numerator, right
i mean
denominator
Yeah I got around to making (sec^2.. ) to 1
okay cool
i tried to make tan(2x) to become tan(x) as well using the trig identity
what i like doing is looking at a table of trig identities
lets do that
ohay you did
https://proofwiki.org/wiki/Trigonometric_Identities for reference though
tan(2t)=(2 tan t)/(1-tan²t)
what happened when you tried that
the equation got super big unfortunately 😭
also the way the formula is framed is dumb
what if i wrote F(t)+5 + C
its not unique
anyway
try it but writing "t" instead if of "tan t" to make it less messy
right
take ur time dw
$$\int \frac{-t + \frac{2t}{1-t^2}}{-\frac{2t}{1-t^2}t-1} , \mathrm dx$$
gfauxpas
okay this isn't so bad
how do we simplify this, any ideas?
multiply top and bottom by ...
take out t on top
yes sure
$$\int \frac{-1 + \frac{2}{1-t^2}}{-\frac{2}{1-t^2}t-1} , t ,\mathrm dx$$
gfauxpas
hmmm but then I can't seem to cancel the terms after doing so since the signs are different 😭
when you have a nested rational function like
Why not simplify the numerator and denominator by giving common denominators to both terms on top and bottom and then cancelling the similar denominators
thats what i was trying to say, what Artemis was saying, he typed it out better and faster than I
dont start over, you did what you did
multiply top and bottom by something clever
right
which is? take a look at numerator and denominator seperately
there's something you can multiply numerator and denominator by simultaneously
to simplify
(-1 +t^2+2/1-t^2)/(-2-1+t^2/1-t^2)
yeah like this
PEMDAS my friend
take a look
I think at one point i got the same thing
alright
PEMDAS
BODMAS*
(tan (x) +tan^3 (x))/(-tan^2(x)-1)
yes i got it now XD
I realised where I went wrong initially
I didn't notice that I cancelled the terms and continued which resulted in a fat expression
thanks guys :D
btw
the correct way to make an intergral a function
is to set one bound, usually the lower bound, as a constant, and the upper bound as a variable
I already stated the problem with saying "let C = 0"
thats not your problem
im criticising the person who wrote the problem
yeah I get that
=>(-1 +t^2+2/1-t^2)/(-2-1+t^2/1-t^2)
=>(1+t^2/1-t^2)/(-3+t^2/1-t^2)
=>(1+t^2)/(-3+t^2)
=>-(1+t^2/2+1+tan^2)
=>-(sec^2(x)/2+sec^2(x))
Guys I have my phy exam tmrw and Im stressed
final answer 0?
you still have to integrate!
yeah after integration
so I got -tan(x) after simplifying allat
and then it is -ln|sec(x)| after integration
input 2pi
which is 0
since ln(1) = 0
right?
you wrote sec^2(x)/2 + sec^2(x) whcih is 3/2 sec^2(x) which has antiderivative 3/2 tan(x) so I suspect you didnt write parentheses correctly
@wheat egret Has your question been resolved?
where did sec^2(x)/2 + sec^2(x) come from?
oh art3mis said that sorry, I thought you said it
my bad!
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@thorny skiff Warum hast du mich von deinem Server verbannt?
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I apologize for the incident.
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How do i do this small angle approximation?
What's the approximation? cos(theta) = 1-theta ?
How small is theta? theta = -2747347234734? Or smaller?
i have also seen cos(θ)=1-θ^2/2
just substitute that in to the left hand side
Right so replace cos(theta) by that, and cos²(theta) by (that)²
and ignore any cubic/quartic terms
is there any @zenith lantern ?
ive got the answer but i don't get the third row where the 1/2 at the end turns into a 1/4 and there is also a -(theta) added into that same bracket at the end
.
wdym
yeah i know why it becomes 1/4(theta)^4 now but whre does the other theta come from?
(a-b)² = ?
a²-2bc+b²
-2bc ??
(a-b)(a-b) right?
Yeah, where does that c come from?
Right, so can you do that when a = 1 and b = 1/2 theta² ?
You did it yourself
much appreciated!
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need help with this limit
I’m assuming sen(𝑥) is the spanish translation of sin(𝑥)?
start by replacing y+1 with a new variable
note that y+1->0 is interchangeable with y->-1
theta is arbitrary
it is not
not necessarily theta -> 0
oh
insee
yeah okay
you allowed to use sin x ~ x for x near 0?
that deals with sin(w³), though not sin(1/v)
yes but use it as an upper bound for |sin(x)| < |x|
assuming the limit is 0
if not, mine is better
guess it doesnt matter
just how i would do it but youre not obligatdd to follow my style
can you elaborate?
what would be the upper bound
I forgot to put an absolute value to the first upper bound
my bad
its not bounding, its asymptotic equivalence
if lim x->0 f(x)/g(x)=1, then
you can replace f with g in a limit expression approaching 0
but your way is fine
hmm what if you took andolute values and replaced r->0 with 1/n ->0 as n-> +infinity
idk if it would work but maybe try it
works at infinity
yeah
show me what it becomes if we change r to n
yes it works @buoyant jetty
but
in retrospect
so does the current form
im so fucked
exam is in a week or so dude
I dont want to say it but I am so fucked
but all your work is correct
you just didnt finish
use triangle inequality on |r sin t - 1|
<=|sin t - 1| (for |r| < 1 )
@buoyant jetty Has your question been resolved?
squeeze theorem now
,align &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2} \ &\lim_{(x,y) \to (0,-1)} \left|\frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2}\right| \ &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot |\sin((y+1)^3)| \cdot \left|\sin\left(\frac{1}{x}\right)\right|}{|2x^2 + (y+1)^2|} \ &\leq \lim_{(v,w) \to (0,0)} \frac{|w| \cdot |\sin(w^3)| \cdot \left|\sin\left(\frac{1}{v}\right)\right|}{|v^2 + w^2|} \ &= \lim_{r \to 0} \frac{|r\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r^2|}
f
,align &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2} \ &\lim_{(x,y) \to (0,-1)} \left|\frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2}\right| \ &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot |\sin((y+1)^3)| \cdot \left|\sin\left(\frac{1}{x}\right)\right|}{|2x^2 + (y+1)^2|} \ &\leq \lim_{(v,w) \to (0,0)} \frac{|w| \cdot |\sin(w^3)| \cdot \left|\sin\left(\frac{1}{v}\right)\right|}{|v^2 + w^2|} \ &= \lim_{r \to 0} \frac{|r\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r^2|} \ &= \lim_{r \to 0} \frac{|r| \cdot |\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r|^2} \ &= \lim_{r \to 0} \frac{|\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r|} \ &= |\sin(\theta)| \cdot \lim_{r \to 0} \frac{|\sin(r^3\sin^3(\theta))|}{|r|^3 \cdot |\sin^3(\theta)|} \cdot |r|^2 \cdot |\sin^3(\theta)| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right| \ &= |\sin(\theta)|^4 \cdot \lim_{r \to 0} |r|^2 \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|
why did you write the whole thing in latex for
i mean, go ahead, why not
but we could read it
already
Renato
sorry
its just that the picture was kinda blurry because discord compresses images
it doesnt bother me, it just seems like a waste of time for you
alright, now what?
do you agree with my work so far?
i checked the first version and it was right, i dont feel like checking this version lmao
agree?
ye, but we have |sin|
0 le |sin(f)| le 1
|sin| <= 1
I was editing
yeah
now multiply all three terms by anything > 0
anything like what
like |sin(t)|^4
dude but hear me out
👂
,align &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2} \ &\lim_{(x,y) \to (0,-1)} \left|\frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2}\right| \ &\lim_{(x,y) \to (0,-1)} \frac{|y| \cdot |\sin((y+1)^3)| \cdot \left|\sin\left(\frac{1}{x}\right)\right|}{|2x^2 + (y+1)^2|} \ &\leq \lim_{(v,w) \to (0,0)} \frac{|w| \cdot |\sin(w^3)| \cdot \left|\sin\left(\frac{1}{v}\right)\right|}{|v^2 + w^2|} \ &= \lim_{r \to 0} \frac{|r\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r^2|} \ &= \lim_{r \to 0} \frac{|r| \cdot |\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r|^2} \ &= \lim_{r \to 0} \frac{|\sin(\theta)| \cdot |\sin(r^3 \sin^3(\theta))| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right|}{|r|} \ &= |\sin(\theta)| \cdot \lim_{r \to 0} \frac{|\sin(r^3\sin^3(\theta))|}{|r|^3 \cdot |\sin^3(\theta)|} \cdot |r|^2 \cdot |\sin^3(\theta)| \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right| \ &= |\sin(\theta)|^4 \cdot \lim_{r \to 0} |r|^2 \cdot \left|\sin\left(\frac{1}{r\cos(\theta)}\right)\right| \ &\leq \lim_{r \to 0} |r|^2 \ &\lim_{r \to 0} -r^2 \leq \lim_{(x,y) \to (0,-1)} \frac{|y| \cdot \sin((y+1)^3) \cdot \sin\left(\frac{1}{x}\right)}{2x^2 + (y+1)^2} \leq \lim_{r \to 0} r^2
since both |sin(something)| <= 1
we bound it from above with this
Renato
yeah sure
in fact if I were the professor I'd allow you to just say
<= lim_{r to 0} |r|^2 = 0
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So they say that the Lebesgue-Stieltjes measure is the completion of the Borel measure mu_F but then how do they know that it must be that infinum thing they give? It seems there is a jump as isn’t it possible for the completion of the borel measure to be something else?
you can also try #advanced-analysis
Like someone told me it follows from defn of pre measure
Ok
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This would just be the number of ways to partition 8 elements into groups of 2, right
yes
wai
yes
in proving that H is a subgroup?
do multinomials take into account that the ordering of the cycles themselves don't matter?
well, choosing 1 & 2, then 3 & 4, ... should hopefully be the same as choosing 3 & 4, then 1 & 2, ...
oh
the binomials only need to care about the order of the things they're collecting in a singular bag, but multinomials only consider the ordering of the objects in each bag, not the bags themselves, right?
binomials take care of two bags
the objects that you choose and those that you dont
they are also multinomials
yes, but in (4 choose 2), choosing 1 and 2 is different from choosing 3 and 4
yeah divide by 4! right?
that's what I think, yeah
mod out permutations of the bags themselves, not just the ordering of the objects in the bags
you still do that (dividing by 2!) when there's only two 2-cycles to consider
yup there are 3 in A_4
sorry, I had gone to use the toilet
hmm?
how many unique products of two disjoint 2-cycles can you make in S_n? choosing two for the first cycle, then choosing another two for the second cycle, yields (n choose 2)(n-2 choose 2) = (n choose 2,2). but wait, because you have commutativity between disjoint 2-cycles, so divide this count by 2
ah
(12)(34) = (34)(12)
right, I did think of dividing by that, but it felt sus
but you don't divide by 2! when you're just splitting 4 items into two groups of two
or do you
i think i should stop talking and not confuse wai
disjoint 2-cycles are commutative
yea,my bad
Okay, I'll do this now
The 2nd part ( finding the number of elements) is simple
it's 3!( As where 1 and 3 go are fixed)
in binomials, you don't because you only ever cared about the objects you're choosing, with no implications on the fate of the unchosen
fate of the unchosen sounds ominous
Sounds like an indie video game lol
it's the title of a post-capitalist horror game, next to night of the consumer
closure under inverses and products, or the one-step subgroup test
my book had 2 different theorems for proving a subset of a group is a subgroup
The question is how would I prove closure here
inverses is easy enough
take two permutations that fix 1 and 3; does their composition also fix 1 and 3?
So I have to compute , no abstract proof is possible
alpha(beta(1)) = alpha(1) = 1
well
I mean, it's really highly unnecessary, but the collection of permutations that have two fixed points in 1 and 3 might be the kernel of a homomorphism S_n -> S_{n-2}
😭
but then you have to address the shuffling of the entries in the canonical choice of set that your permutations permute lol
I havn't dones this yet 😭
ok I thought so, but that is at least another way! but the thing Axe said is like, a two-liner
Got it
thanks
So my issue here is there's no assurance that an element of $H$ has to have even order is there
wai
if this is your first time reading the question, you might be better off thinking about it for a bit before someone else steals the experience lol
It is my first time yes
I had to stop myself from giving a hint because the answer I had excited me
okay, I'll think about it for a bit , I just wanted to finish this as I have an exam on this in like 40 hours lol
can't we at least give a small hint?
with permission
The current time for math_rocks is 12:39 AM (IST) on Thu, 18/09/2025.
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Two points are given, each a finite distance apart. Both points are the centers of circles with radii equal to the distance to the other point. The two resulting circles have two intersection points, which are the centers of new circles, with radii equal to the distances to the centers of the initial circles. The process is then repeated indefinitely. The resulting construction consists of the intersection points of pairs of circles, which in turn are formed by this point, and a radius equal to the distance from this point to some other point besides itself. The process is repeated for all combinations of points, so that each point is the center of a circle, and each distance between pairs of points is the radius of some circle.
Determine:
- What construction is obtained from circles and points.
- Define it analytically for further analysis.
- Analyze this construction.
Help with 2 pls
I did a little sketch
so you can get an idea of what it is
Wait am I in the wrong channel
