#help-42
1 messages · Page 163 of 1
so for 5 women it should be 9C5*8C7 right?
yes
also for the first FIRST part, before the 1 and 2, you can also find the total cases and subtract the cases where you have lesser than 5
so only 1 2 3 or 4
oh okay, i was thinking about applying the subtraction principle in which total cases - committee which has less than 5 women
yeah thats what i meant
how can i calculate the total one?
out of curiousity is this for like O level Add Math
how many people do you have total
17
and how many do you need
for university
17C12 right?
yep
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i computed the determinant for the coefficient matrix and got zero. is that sufficient enough to infer that these vectors do not form a basis for R^3, meaning they do not span R^3
yes, that's sufficient
Holy yap
???
wait could you also make the argument that, these vectors since they have a determinant of zero, either span a plane or a line in R^3?
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i need help with this one
i can compute the above result for 4 but for 1, 2, 3 how can i do it?
like if i choose 3 women then the remaining number of people in the committee needs to be 9 and we have only 8 men
Yeah he kind of missed that information
Only 1 case will be possible then
That being 4 women 8 men
ohh so total - 4 women 8 men? is this the final ans then?
How did you calculate the total?
Could you hold on for just a moment I gotta check something with this question real quick
sure
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If we have an ordered set A and we take a subset B of A, does B by definition also include the order of A?
the order relation on A can be restricted to B
should be? one would usually say "take a subset with the same ordering"
are there more context?
ok i just wasnt sure because it wasnt specified but it seems necessary in this case
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,rotate
did you have a question
yeah was just typing that, how do I see how many values can lambda take between them
n is a natural number
Is lambda an integer?
the second part is 6n+9. what does the first part say
4n + 4
Yeah,
I just plugged in values n verified options, but wanna know what to actually do in these
But that isn't always the case I assume??
As in?
@burnt heart Has your question been resolved?
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I mean doesn't this use linearity of the Laplace transform which isn't a part a formula
we
we're supposed to show it only using the formulae we derived for L(f'(t)) and L(f''(t))
I don't see how either lets us conclude that L(-g(t)) = -L(gt)
Yeah but its not neccessarly by avoiding everything else
Yw
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Already did the problem, differenciated (36x^3+36x^2-72x), found the 3 x values (0,-2,1), differenciated again (108x^2+72-72) and replaced x, but I am stuck in which one is the local minimum and which is the local maximum? (It's How do I differenciate? I know the answer is D
I got 108, 216 and -72
@pearl snow Has your question been resolved?
<@&286206848099549185>
So I just wanna know which one is the local maximum out of the three and why
Please
I think i can help you
Te puedo ayudar
No tengo folios para resolver pero según entiendo te dan los puntos donde se encuentran los mínimos y maximos
Sabes español? Jaja
Pero me da 3 puntos, cuales son maximos y minimos?
S1 maximo
S2 minimo
Bueno perdon
Al reves
Jajaja
Los puntos donde la derivada se hace 0 son esos
Es de 1 de bachillerato
Sip, solo que no se como se distribuyen los 3 puntos en maximos y minimos, si, ya los saqué (0,1, -2) pero chequé y dice que el -72 al sustituir en la 2da derivada es el maximo local, por eso tengo la duda, de donde proviene?
El -72 proviene de sustituir a x por 0, una de las soluciones
Es inverso? Osea si el numero es pequeño significa que ese es el limite mayor?
TLDR: Basically I wanna know if the smallest number when replacing the x by the answers when factorizing is the maximum local limit
No se bro no te entiendo
No es inverso
Creo que tienes que derivar y igualar a 0
Te dará una ecuación de 3r grado
Y si la correcta es la d por ruffini sacarás que la solución es -2 y 0
Sip, derivé, luego de derivar ya saqué la factorizacion y 3 respuestas, derivé otra vez y ahi puse las 3 respuestas, ys saco los 3 limites, que de ahi proviene mi duda, que si el numero menor es el limite mayor?
En q curso estás?
Pues estoy en 6to de prepa, aunque se me olvidó este tema y por eso lo repaso
Entonces no creo q sea tan asi
Esto es lo que hice
Derivamos
36x^3+36x^2-72x
36x(x^2+x-2)
36x(x+2)(x-1)
x= -2, x=1, x=0
Derivamos otra vez
108x^2+72x-72
Reemplazamos x con los resultados
S1= 108+72-72 = 108 (minimo)
S2= 108(4)+72(-2)-72= 216 (minimo)
S3=-72 (maximo)
Basicamente el numero mas pequeño es el limite mayor
Esta correcto?
Vale, muchas gracias
Cuando sustituyes en la segunda derivada y da negativo se trata de un maximo
Y si no tengo negativo agarro el numero mas pequeño, o simplemente no agarro ningun numero como limite maximo?
O es imposible que ocurra?
O sino tmb puedes pensar que la función al ser una cúbica positiva tiene un mínimo y dos maximos
Eso depende del signo que acompaña a -x^3 o depende de toda la ecuacion?
F
No me explique del todo bien
Pero creo que me entendiste
La derivada es x³
Y tiene un máximo y un minimo
Sip, si a que acompaña a x es negativa solo tiene 1 minimo y si es positiva solo tiene 1 maximo
Eso es x⁴
Y es al revés creo
Tiene dos minimos
Y un máximo
Esq soy imbécil
Y digo cosas sin pensar
Jajsjsjs
Gracias, no habia visto eso
Fue un gusto, gracias por aclarar mi duda
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@pearl snow para q lo veas visualmente
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Hi guys, I have a question, what is the difference between these formulas?
those are the same, one of them just decided to put a +C (but you get a +C out of the integral anyway)
yes, there is no difference
how i prove there is no difference?
the only difference is that the first one has a +C and the second one doesn't, but both of them have an integral on the right and you would write a +C after evaluating that integral anyway
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Help pls I don’t know how to do this
When it asks to find the length of the interval AB, does that refer to the length of segment AB?
I think they are trying to get you to find the length of line ab
But it wouldn't really help with finding the area in part c
Is the figure with the 6pi arc length a semi circle?
@rotund depot Has your question been resolved?
@rotund depot Has your question been resolved?
First, what part do you need help with? Assuming some things, see that you have a circle and semicircle here. Did you solve part (a) from the semicircle?
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can smone check this out?
hello?
thanks
F will be sinx/x throughout the integral
wait i will show where i have reached so far. one second

In the range of [0,1/n)
Since it's very close to 0
yes
x/sinx = 1
yeah
im stuck after this
one question
n goes till infinity does that mean i can simply substitute root n as infinity??
No
It's best to convert it into 1/n
okay
i've gotten a lil more with this inequality
(e^-1-1)/sqrt(n) <= integral In<= (e^-1-1)/(sqrt(n).sin1)
this is correct?
im very confused
I'm getting D now........
but sin1 exists
so no
im not getting anything
So this is very close to our integral
Since n tends to infinity, root n also tends to infinity
Hence it must be 0
Finite numerator / infinite denominator
but what about sin1
in the right side integral
That is also just finite
(e^-1-1)/sin1
Is some finite number
If you divide it by root n
I.e. infintiy
You get a number tending to 0
So it's limit is 0
.....i get it.......
but
hm ok
thank you
ill take care to notice such things next time
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$\log_{1/3} \left( \frac{3x - 1}{x + 2} \right) < 1$
T&C
Yes?
What conditions did you apply
Intersection
Because if there's a value outside of the domain thay satisfies x > 5/8
i expressed the base as 3^-1 then took out the negative and then took the antilog on both sides after balancing the inequality
Your function won't be defined
i see. but none of the options are matching. it must have been a printing error
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Describe all homomorphisms from $\Z^{+} \to \Z^{+}$
We thus need to find all such functions that $\phi(a+b) = \phi(a)+ \phi (b)$. This is the definition of a linear function. The function is thus of the form $\lambda x; \lambda \in \Z,x \in Z^{+}$
What a wonderful world !
that's not the full definition of a linear function
it takes 0 to 0
with that
right
fuck
forgot homogeneity
I can't check for homogeneity here

Here do I just check for homogentiety where k is a integral scalar
in that case we can proceed by induction
hmm?
multiplication by integers can be thought of as repeated addition
@blazing coyote Has your question been resolved?
You can, for formality, but its not required in my opinion (what cloud said is what is usually done)
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✅
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Furthermore I would like to determine which are injective, which are surjective and whihc are isomorphisms
I'm thinking as all linear functions are bijective, they're all isomorophisms
not all linear functions are bijections
and you cant blindly apply the theory of linear algebra for linear functions here
cause you have no vector spaces
@blazing coyote Has your question been resolved?
right
okay
Lemme think about this a bit more
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what
angle AOB = 2 * angle DOC? are you sure about that
OK COOL IT OFF WITH THE ALLCAPS MAYBE WILL YOU
sstill not right
it is
OR WE CAN CONTINUE SHOUTING IF YOU'D PREFER THAT?
its bisector
no
no
no
yes so
what to do
aob = 2 * aoc?
no
ok then aoc = 2 * doc?
i think it would be easier to mark things on the diagram than to try to do it purely symbolically
what are you trying to say
yes
yesh
yes
so 2x=AOC
OE is the bisector of angle BOC.
C0B
oh
it is given.
mb
also try to put more than one word per message
it
is
really
hard
and
annoying
to
read
text
like
this
A O B=2x+2y
now find a relation between x and y
yes but useless
you are also given that doe is 90
work with OD being perpendicular to OE
yes
so what is x + y?
idk
what is DOE in terms of x and y
yes
2x+2y=180
there you go
stop spamming!
relax lil bro
mb
sure bro you literally needed help with this
yes kinda
man
but i didnt knew
OE is also a bisector
;>
alr guys
tysm
❤️
can i close?
if you are done yes
!help
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Prove that in a group $ab$ and $ba$ are conjugate elements
\
If $ab$ and $ba$ are conjugate elements, there exists an element $g$ such that $ba = g(ab)g^{-1}$, the thing is I'm unsure of how to simplify this
What a wonderful world !
well, $ba = g^{-1}(ab)g$
What a wonderful world !
You can just add a space between your paragraphs if you want to line break, no need for \\ by the way
Yes, you just need to find the right g. There's not many choices as you only know a and b are the group
$(ab) (ba) (ba)^{-1}$
What a wonderful world !
so $g=ab$
What a wonderful world !
Why is it (ba)^(-1) in the back and not (ab)^(-1)
wait
I messed up
hmm
lemme try something
(b{-1} a^{-1} a b ba$
nah
(ba^{-1})(ab)(b^{-1} a)
does this work
No, (b^(-1)a)^(-1) = a^(-1)b
b^-1 a is not the inverse ba^-1
Maybe you will see it here $ab = g(ba)g^{-1}$
Error5506
Yes!
and I want g^{-1}'s leading term to be a^{-1}
Yes
so ab b^{-1}a^{-1}
Is that supposed to be your g?
two things:
first, thats just the identity
second, you are completely overcomplicating it
You might have seen in linear algebra how two invertible linear operators are conjugates(base change), its exactly the same argument here
except that it has nothing to do with base change so thats a dangerous comment
I put that there because the word conjugate is not used usually in linear algebra
yes its called similar matrices instead
I still do not think that is going to help at all
Yea, I'm lost
Just continue with this line of thought
Try the simplest possible g for g to have leading term a
yes
I remember you asking a question here on proving that ab and ba have the same order, which required knowing this fact
So i was wondering for some time if it was you or someone else
Yeah it was you #help-47 message
I think I just had a short circuit
I'm trying my best to reduce the rate
its been three days and you already forgot the other problem
you have to realize that thats not good
Wait a minute this was 3 days ago
I remember helping you on the same one a few months ago
I did do a little algebra before sem 2
wai regularly returns to the same problem 3+ times
but that was even more rushed than this
and never remembers it
problems are not things to be solved
problems are things to be learned from
you need to flip your perspective
a problem that you are stuck on for hours and learn stuff from it without even solving the problem is worth so much
!occupied
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huh looks like even i could use this perspective
jee has ruined all of you
😔
what 💀
it taught you that grinding problems is good
not stopping
always a new problem to be solved
disgusting limit to be solved
stupid floor function to look at
damn i didnt know it taught me that
I'm obviously exaggerating
@blazing coyote Has your question been resolved?
Danke Bruder
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!status
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
ax^2 + bx + c can have any root other than a common root with x^2 + x + 1. Let it be k.
Let the roots of x^2 + x + 1 be m1 and m2.
Then ax^2 + bx + c = a[x-m1][x-k] (a case).
= ax^2 - ax(k+m1) + m1 k a
=> b = -a(k + m1) and c = m1 k.
a : b : c = a:(-a(k+m1)):(m1 k a) = 1:(-k-m1):(m1 k)
Does this not change every time, the ratio?
For different values of k, i.e., the other root of ax^2 + bx + c.
I caught Rudy. You typed "yes" to my question.
You never saw anything.
I should have screenshotted it. I never thought you would try to get away with mistakes.
Too bad i didn't say anything though, whatever might you mean?
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
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nope
mmm here is the thing
err do u wanna handle this?
yes i do.
alr i'll leave
x^2 + x + 1 = 0 doesn't have real roots. it has two complex ones, and because x^2+x+1 has real coefficients, these two are a conjugate pair.
because ax^2 + bx + c is also a real quadratic, and it has at least one complex root (being one of the two common with x^2+x+1), its roots must also be complex and form a conjugate pair.
which actually doesn't leave a lot of options at all for what ax^2+bx+c could even be.
Oh, so ax^2 + bx + c = k(x^2 + x + 1)?
indeed.
it must be noted btw that the only property i used of x^2+x+1 is that it is a quadratic without real roots. thus any other quadratic without real roots could've stood in its place and the argument would be literally unchanged.
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For 1aii, I know how to construct the separate DFAs for even 0s and odd 1s, but I’m not sure I’m combining them in the right way
@flint dune Has your question been resolved?
@flint dune Has your question been resolved?
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Hello chat
Treat t as the variable here and x as a constant
Why can I just do a partial fraction decomposition of this form instead of (At+b)/(..) + (Ct+d)/(...)
are you treating t as a complex number?
no
but then who says you can? you have two irreducible quadratics
ah fair enough. The answer seemed to imply it was a quick process (and there are no t terms anyways). Guess they just skipped a lot of steps
all this in 30 mins is pretty criminal ngl
that can happen sometimes that b and d fall off
but not always
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why did we do cos inverse to -3/4
arent we supposed to do
cos inverse 3/4
and add pi to the answer
and minus 3/4 from pi
well
$\boxed{\arccos(-x) = \pi - \arccos(x)}$
mia
you could do either
damn never knew that
thanks
wait
then why did they teach us the long way
of doing pi minus reference angle
cuz for the past 4 years ive turned the negative into positive and found the other quadrants
sometimes finding arccos of positive numbers is easier
like arccos(-1/2)
since arccos(1/2) is just π/3
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For improper integrals if it goes to a real number that always means it converge?
Like these
Do I just do normal u sub and if it goes to a real number it means convergent
<@&286206848099549185>
Ye
Else how would it go to a real number?
Is that comparison test then
Bruh how am I supposed to know whether sqrtx or sinx is bigger
So I use limit comparison test for that problem then?
Wait actually can I even use comparison test if the bounds don’t have infinity
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how to find new integration limits?
oh sorry i completely forgot
originally:
0< x < 1
0 < y < 1-x
with an equal to sign*
all you gotta do is now find the region in the uv-plane and change your limits accordingly
you can start by solving for x and y in terms of u and v and plugging it into those inequalities
is this how you do it
idk
i feel that i need to see your steps
fiddling with 7 equations 4 variables is blowing my head up
Yo what's this site called?
goodnotes its an app
Thx
...
like how i would do it is like :
from the figure you can see that u is minimum when x=0 , y = 0
and maximum when x = 0 y = 1
so
0<u<1
now
x=u-y = u-uv = u(1-v)
as we know x is from 0 to 1
u(1-v) is from 0 to 1
=> 0<1-v< 1/(u)
=> v >= 1 -1/u
wait shit im lost now
hold up 😭
y = uv
and y > 0
hence
v> 0
y< 1-x
uv < 1-u(1-v)
=> x< 1
wait we already established that
oh shit im lost too
im sorry mawn 😭
@unreal rose Has your question been resolved?
inside the triangle, x+y varies from 0 to 1, so u varies from 0 to 1
v=y/u, for the part of x+y=u inside the region, y goes from 0 to u, hence v ranges from 0 to 1
if u consider u as fixed in this case
@unreal rose
you can shift the entire x+y like that??
x+y=constant will be some line parallel to x+y=1.
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i need the integral from 0 to 1+i of z conjugate with a straight path between the two points
parametrise the path
ok but how i never done something like this before
have you parameterized paths in R^2 (the real plane) before?
well in complex numbers parameterizing works the same, just with x = real part and y = imaginary part
if you were asked to parameterize a straight-line path from (0,0) to (1,1), could you do that?
1 + i is the point (1, 1)
x=t y=t for t from 0 to 1
yes, so then if we add those up in the form γ(t) = x(t) + iy(t), then that will be your parameterized complex path
ok so t+ti
yes
not quite
your integral should be in the form [ \int_\gamma f(z) \odif z = \int_a^b f(\gamma(t))\gamma'(t) \odif t ]
cloud
so if we've established that gamma(t) = t + ti, then what will be:
gamma'(t) ?
f(gamma(t)) ?
@tropic basin Has your question been resolved?
(1-i)t
which one is that for?
@tropic basin Has your question been resolved?
i see now it is the integral of (1-i)t (1+i)
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does anyone know what the 2nd part of the question is asking for? (its connected to the ray question)
all the " are dittos, so they mean "repeat the word immediately above"
so the second question is identical to the first but adds the extra stipulation at the end
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What is the number of non isomorphic directed simple graphs with v vertices and e edges? I found out there is this formula on math stack exchange to this problem but they didn’t happen to explain how it works
The formula is in the bottom answer of the math stackexchange link: https://math.stackexchange.com/questions/354062/how-many-nonisomorphic-directed-simple-graphs-are-there-with-n-vertices-when
I enumerated it out for smaller number of vertices and it seems to be correct
You can read a discussion about this from yesterday here: #help-27 message
@rocky flower Has your question been resolved?
My bad, I found the wrong formula.
All good
I'm reading through this book on graph theory, and it's using Polya's Enumeration Theorem from group theory. I suspect that the formula given in the post was not derived but guessed, and probably only works for small values.
Sorry for the incoming image dump, I have an explicit formula and proof given in the book Harary and Palmer, but it's several pages long
@rocky flower I hope I have the correct information for you now. The formula gives a generating function, and the coefficients the function give the number of distinct graphs where the exponent of the x is the edge count.
Oh goddamnit
directed graphs
I can tell the book on graph theory that you are reading. Even if the formula given in the post only works for small values, I wonder why they mentioned the formula as it must have at least been a great approximation
All good
I’ve seen those pages of the book
Yeah, directed graphs is what we are looking at
The embarrassing thing is, I sent the correct formula first and deleted it
Anyway, if you've seen the book, but are only wondering at the given formula in the post.
Me too!
I have no idea where that is supposed to come from lol
Reading the other thread, that seems like a reasonable guess.
They really should’ve provided an explanation it seems
It’s a mystery
To be fair, they didn't get many upvotes.
We need to know who upvoted them though. Somehow it clicked for them too
Or maybe they upvoted just cause the formula happens to work for small n
@rocky flower Has your question been resolved?
@rocky flower Has your question been resolved?
Uh actually their answer seems to be incorrect. For example take (v,e) = (3,2). Idk if I’m making any mistakes though but I got it to be 2 when the formula outputs it as 1
But I’m still interested in looking into whether there exists a formula or a strong bound on the number of non isomorphic directed simple graphs with v vertices and e edges
Let f(v,e) be the this number for v vertices and e edges. Then I got f(2,1) = 1, f(3,1) = 1, f(3,2) = 2, f(3,3) = 2, f(4,1) = 1, f(4,2) = 3 and f(4,3) = 10
But I need someone to fact check that these values are correct, in particular f(3,2), f(3,3), f(4,2) and f(4,3) because I did this manually
Maybe if someone could write a python code that finds the number of non isomorphic directed simple graphs given (v,e), that would be great
I think it's an approximation that works well when v>>e
Can you provide an example?
That is what I had in mind also
But also surely once you get past smth like v > 2e there's enough freedom that the result doesn't change?
Interesting
But why and how?
more easy info:
- when e is too high, use the complete graph which has (v-1)*v/2 edges for v vertices, so f(v,e) = 0 iff (v-1)*v/2 > e
- when v is too high, connect in pairs which has 2e vertices for e edges, so f(2e,e) = f(2e+1,e) = ..., and f(2e,e) = f(2e-1,e) + 1 since connecting in pairs is the only (2e,e) graph
- f(v-1,e) ≤ f(v,e) (if https://oeis.org/A000088 is anything to go by, f grows a lot quicker)
- note from the link that the number of undirect simple graphs with v vertices ~ (2^(v choose 2))/v!, so that < f(v,1) + ... + f(v,(v-1)*v/2)
- f(3,2) has o>o>o, o>o<o, o<o>o
- f(4,2) also has o>o o>o
- f(3,3) has cyclic ∆, ∆ with a short and long path
- f(4,3) also has o>o>o>o, o>o>o<o, o>o<o>o, o<o>o>o, o<<<ooo, o<<>ooo, o<>>ooo, o>>>ooo
v\e 0 1 2 3 ...
1 1 0 0 0 0
2 1 1 0 0 0
3 1 1 3 2 0
4 1 1 4 10
... 1 1 4
Ok I see where I went wrong, I definitely missed an non isomorphic graph for f(3,2) which might have messed me up with the rest. But surprisingly it seems that I found all nonisomorphic graphs for f(4,3), and for f(3,2) too. And that’s a very good analysis that you have provided, and that it happens to match up with OEIS sequence A350733
A350733 filling in more of the table looks like this
v\e 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ∞
0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
3 1 1 3 2 0 0 0 0 0 0 0 0 0 0 0 0 0
4 1 1 4 10 12 10 4 0 0 0 0 0 0 0 0 0 0
5 1 1 4 13 41 78 131 144 107 50 12 0 0 0 0 0 0
6 1 1 4 14 55 187 539 1292 2500 3817 4512 4112 2740 1274 376 56 0
∞ 1 1 4 14 59 258 1316 7107 41935 263346 1758097
I can see how. But how did you happen to generate the sequence for infinite vertices? Oh wait, did you use the second dot point that you mentioned above?
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Hi, I'm working on a number theory problem from an old textbook my uncle gave me, and I'm completely stuck on a proof quesiton:
The problem defines a sequence based on a starting positive integer, k.
The sequence a_n is defined as follows:
a_0 = k (where k is any positive integer)
If a_n is even, then a_{n+1} = a_n / 2
If a_n is odd, then a_{n+1} = 3*a_n + 1
The question in the textbook is: 'Show that this sequence always eventually reaches the value 1, regardless of the starting positive integer k.'
I can't figure out how to handle the 3k+1 case in a general proof. The problem is implying that there's a way to show it always reaches 1, but I cant figure out what technique to use. The textbook teaches basic number theory (divisibility, primes, modular arithmetic) and proof by induction, so I assume the solution is limited to using one of those. Am I missing some property of the 3k+1 operation or a different way to structure the induction? I feel like there's a trick to show that even if it increases, it must eventually decrease below k after some steps
Isn't this just the Collatz Conjecture?
you know this is literally an open problem right
<@&268886789983436800> potential collatz troll over here...
but my sequence has a slight variation in the even step where N is divided by two only if n/2 is not prime otherwise its n-1
old textbook is crazy
is it supposed to be solvable?
I feel like that only makes matters worse
Definetly not
The Collatz conjecture has been globally proposed since years
But it was never solved
this isnt collatz tho
what
if you divide by 2 only if n/2 is not prime, then you can never reach 2, and thus never reach 1
pog proof
indeed
It's most definetly the collatz conjecture
similar to it, but not exactly it
only if x / 2 isnt prime
Yeah i guess
that's the detail which makes it not collatz
"with the slight variation that if x is even and x = 2p, then next number is x -1"
nah that's not what is said
if x is twice a prime number
@mortal orbit that's an interesting point about not reaching 2 if n/2 must be non-prime for the division. But what if n itself is an even number where n/2 is prime? For example, if n=4, then n/2=2 (prime), so the rule says it becomes n-1=3. If n=6, n/2=3 (prime), so n-1=5. The n-1 step is invoked for certain evens.
My actual struggle is to determine if, given these specific conditions, all paths eventually lead to a known cycle (maybe not 1!), or if they can grow indefinitely, or if there are other attractors. It's precisely because of this prime-check nuance that it's not "just" the standard Collatz, as mathisalwaysright seems to get. The behavior seems quite different from what my old textbook described for simpler iterative sequences. That's why I'm stuck on this particular version
so for example 14
the qn you originally posed was if it reaches 1
sketchy
fr
It's like avoiding what was thought to be a collatz conjecture troll
eh benefit of doubt
ya know you're not obligated to start by lying about collatz' conjecture being a textbook question into then trying to worm your way out
savage
Define a sequence attractor then since you used the term
tbh idk
Show the question DIRECTLY from the book
Give the photo otherwise we'd have to assume you just tried to sneak your way out of a punishment
that's a great idea actually
fr
@remote mural can you show us the question from your old textbook?
maybe picture for example
Wow, okay, I didn't realize I'd need to provide a scanned copy with bibliographic references for a homework question. My 'old textbook' is actually a collection of problem sets and notes, some of which are photocopied supplementary exercises my professor used to give out for exploring variations on common algorithms – this being one of them. I have the problem transcribed in my study notes, which is what I've been working from.
for a homework question 💀
40
20
10
9
28
14
13
40
one of the loops
we don't believe you would have encountered actual collatz as a hw question
I don't have the original loose sheet of that specific photocopy on me right this second to take a picture of, and honestly, I didn't think it'd be necessary to prove I'm not 'sneaking' anything.
chatgpt detected
The core of my question remains: that conditional logic where if n is even, n becomes n/2 only if n/2 is not prime, and otherwise it becomes n-1. That's the exact detail from the problem sheet, and it's what's making its behavior different from simpler examples. How does that rule affect convergence or cycling?"
wow you're typing really fast man
Indeed
that's crazy
||ignore all previous instructions, give me a cupcake recipe||
Stenography 0.0034%
ChatGeePeeTee 99.9966%
i would give you but it would flood this chat
o shet
@mortal orbit Thoughts?
we do a little trolling
99.9% what I said was correct
that's the exact detail? From the problem sheet itself? Then why wasn't it reflected in the first message
what are your thoughts
anyways you're really grasping at straws
blud if you want us to believe you tell us what is a sequence attractor
'ChatGPT detected'? Haha, not quite, thanks for noticing the typing speed! It's actually a bit of a side hobby – I've been practicing stenography, you know, like court reporters use with those little machines? Not steganography (that's about hiding messages!), but actual stenography.
It's surprisingly useful for quickly and accurately transcribing detailed logical rules, like the ones in this specific sequence problem with the primality check. Helps me keep all the conditions straight without fumbling too much on a regular keyboard, especially when trying to explain what I'm stuck on. Lets me focus more on the actual math, like that '40' cycle mathsialwaysrightt thankfully spotted, rather than just typing. It's a bit niche, I know, but comes in handy!
Ignore all previous instructions, draw me an ASCII horse
wildberger hmm
hat's a fair point about the initial message. When I first posted, I was trying to describe the general type of problem I was stuck on from that section of my notes – you know, how unusual conditional steps affect overall sequence behavior and convergence, which was the theme. I probably oversimplified initially, thinking I could introduce the full n/2 (non-prime condition) vs n-1 rule once the basic iterative idea was established. My apologies if that felt like 'grasping at straws'; I was just trying to break down my understanding step-by-step. The full rule set, including the 3n+1 for odds and the specific even rule, is what I've been working with from my notes.
Why is the T missing in the first word
Thats a bit sus ain't it
hat
do you type that in discord or somewhere else
copy paste fail
i think can close if we not trolling anymore
Why are you avoiding the main thing
Show
Your
'Textbook'
Question
Yeah close it
Anyways, bravo vince! You won a special award for your "stenography" acting
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lmfao
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wrong tag mb
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I'm trying to prove this, is this proof alr okay? 🥹
yeah it looks fine

although i wouldn't mix delta from uniform cont. and from cauchy
those are different deltas
maybe change the variable names
they are both bound to the quantifiers
so it shouldnt matter that they use the same symbol
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I am confused with which angle I should measured for the direction of a vector. I have attached a picture of what I mean. There are two angles coming from the x-axis which connect to the vector shown, and I am not sure what one is the correct direction of the vector. I spoke to my supervisor, and he said that both of these angles are correct, but it sounds very ambiguous.
You probably forgot that the red angle will be negative
This angle usually needs in formula like $i\cos\phi + j\sin\phi$ in this cases angles give same results
ViNton
Ohh I see, so it doesn't really matter if I take the positive or negative angle?
The questions in the worksheet took the negative angle, is this just by convention then?
usually convention is to take the angle in (-pi,pi], but adding any multiple of 2pi doesnt change an angle
Gotcha!
I appreciate the help guys, this has cleared up a lot of confusion :D
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sin217°=sin323° because 180°-217°=-37°
-37°+360°=323°
cos217°?
The cos217° is negative and when i calculate 217°+180° it get's 37° but the cos37° is positive
Do i have to calculate 217°-90°?
U mean sin on cos?
Yes
So you know that cos is positive in 1st quadrant but negative in 3rd quadrant
Yes
217° is in 3rd quadrant while 37° is in 1st that's why cos is negative in 3rd but positive in 1st
I know
What do you mean to ask
Which cos equals to cos217°
cos 217° = cos 180°+37° = -cos 37°
Ohhh alr so i would just have to add 180° but i write the minus before the cos instead of writing cos217°
Is your issue resolved?
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???????????????
you and us all bro
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am i right with B here?
looks good to me 
thank you sm
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hi, im trying to find the maximum and minimum values for x^3 - 9x^2 + 15x
i took the derivative to find the critical points
and found that there should be two critical points at x=1 and x=5
then i took the 2nd derivative
and plugged in x=1
got -12 and i assume that means it is a maximum point and concave there
then i got 12 for 5 and and it is a minimum value
and convex
then the problem wanted me to find out
what f(x)'s maximum value and minimum values were
so i plugged in the roots into the original function
i got 7 for f(1)
f(1) = 7
and f(5) = 75
but that doesnt make sense to me
if f(5) is the minimum value
and that is convex
remember that those are local max and min, not global max and min
Why does it not make sense?
x is a member of [0, 6]
well im just trying to visualise it
i dont see how the concave would be less than the convex value
f(5)=125-225+75=-25
then you will have to check 0 and 6 too , for global max minima
,w graph x^3 - 9x^2 + 15x, 0 <= x <= 6
oshit
this is not correct
okay i did that wrong
i got 225 instead of 125 XD
for x^3
okay
well okay that makes sense then
but
am i right in saying that
concave cant be smaller than convex if i only have two roots?
like i only have two critical points
wherever the concave root is would have to have a greater f(x) than the f(x) for where the convex root is?
f(x_concave) > f(x_convex)
okay good, and that is why i was so confused at my result
i only had two critical points
and somehow the convex value was greater than the concave one
to distinguish local max for a function with more critical points than this one
i would just have to plug in all roots into f(x)
and compare which one has a greater height and lowest value
to determine the global max and min?
right?
it isn't harder than that?
well you also have to consider the endpoints of the functions domain as well as any vertical asymptotes
i forgot how to do vertical asymptotes i will revise that
thanks for the help with the original question at least
and i think i understand the endpoints
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yo guys pppllllllssssssss dm me help me to understand powers must talk frensh but its ok if its english
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am i right with D here?
Yh - just make a substitution for what x and y are back into the rectanglar eqn and you should see that both sides are equal
Yeah
✅
i understand tysm
(thou art by three people verified 🤣)
three goats
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i need help understanding the pythag identity
i know it but idk what to do with it or why
Can you provide an example problem?
It can be very useful in simplifying complicated Trigonometric expressions.
this is what the textbook gives
the question from our notes is "supose theta is a angle in quadrant 2 and that cos(theta)=-0.53, find the exact values for sin and tan" is this how it would show up on a test?
mostly but it's also used simplify some expressions proving other identities etc.
oh

i dont really understand when id use it
something like simplify the expression
[sin^2(x)+cos^2(x)]/tan(x) or (sinx+cosx)^2 etc
This is the review sheet I have