#help-36
1 messages · Page 168 of 1
I guess a way to think of it is that you can imagine I=[0,1] wrapping around the equator of a sphere (or the earth). You just proved you can find a point where g(c)=0. This is equivalent to saying you can find a point where f(c)=f(c+1/2)
If you are at a pt c on the equator of a sphere and you walk half way around the equator you end up at the antipode of a c.
If f is measuring temperature this shows the temperature at c and at the antipode of c are the same.
you can also consider the interval [0,2pi] if that helps
What was the formal proof for the question?
@ionic gate Has your question been resolved?
hi is it okay if i’m in middle school i’m barely gonna start 8th grade and i’m really struggling in 7th grade math. i got masters on my texas starr test for reading but did not meets on my math. any suggestions?
Claim your own channel
Let I=[0,1] and imagine I is a circle (the equator), 0 represents a starting point (e.g. Greenwich) so 1/2 represents the diametrically opposite point and 1 brings you back to point 0 so when u are on 0 or 1 it’s like being in Greenwich so if f is the temperature u have f(0)=f(1) and the temperature is also continuous .
Two points are antipodal if they are opposite each other on the circle, i.e. separated by half a turn, or an arc of 1/2 so if i take a point c between 0 and 1/2 the opposite is c+1/2
I'll let you draw your own conclusions based on what we've proven.
@ionic gate Has your question been resolved?
I meant for the first part.
g is continious on [0,1/2] bcs f is continuous on [0,1] in addition to that g(0)=f(0)-f(1/2) and g(1/2)=f(1/2)-f(1)=f(1/2)-f(0)=-g(0)
let's not live too much, we have two things to do here
First case : if f(1/2)=f(0) so c exists and it is even c=0
Writing out the proof for them seems like doing too much.
Ok ill delete
Summarizing might be a good middle ground?
I'll let you think about the second case maybe
That seems fair.
@ionic gate Has your question been resolved?
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honestly been thinking abt this question for a day-ish, don't really know where to start? could i get a hint as to what i can do to make progress?
hard to give a hint without spoiling it
look for hidden assumptions made in the argument
thats fair
ok
i guess an obvious question is
can $x ~{} y $ even be true if $x \not ~{} x$
lifelong dumbass
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Maybe a better question would start with "must"
thank you
ok i have a question
the above logic assumes that x, y are in the same equivalence class
but what if the equivalence class just contains one element (ie x)
in which case y doesnt exist
and thus the symmetric and transitive properties cant be applied
i mean nobody said y has to be distinct from x
but you're kinda on the right track
namely that questioning whether the things you talk about exist is a good habit in general and also for this problem
uhh ok
well if y and x were the same then you've just assumed reflexive property already no?
What even allows you to talk about equivalence classes if its not an equivalence relation
isnt the point to assume its an equivalence relation and then show a contradiction?
I'd say that the point is finding a relation which is symmetric, transitive but not reflexive (i.e. not an equivalence relation)
showing that reflexivity isnt redundant
oh so thats what they mean by counter example
i guess an obvious example is x < y
Not symmetric
1 < 2 but not 2 < 1
so this was a typo?
sorry im confused i thought you were asking me to find a relation that was
- symmetric, transitive, not reflexive
so how does it help you in finding a relation which is symmetric, transitive but not reflexive
you wont always find a familiar relation which serves as a counterexample
perhaps take some simple set, such as {a, b, c} and try constructing the counterexample on that
ok thank u
to make sure it's not reflexive, say that you'll disallow e.g. a ~ a
now you just gotta make it transitive and symmetric
btw this idea was very close, just rephrase it without equivalence classes stuff
mmm ok
by this you mean assume $a \not \sim a$
lifelong dumbass
or do you mean that the operation just isnt allowed
ye
oh ok
you can use a table to construct the relation ~, or draw some kind of graph with vertices a, b, c (since it's symmetric, every ~ works in both direction)
Can you at least see why it’s not true?
you mean if $a \not \sim a$ or if the axiom is redundant
lifelong dumbass
Second one
why the axiom is *not redundant
right yes my bad
I’m trying to give you this perspective because for counterexamples you usually need to start with some intuition
Okay, what is the exact implication that they claim to be true?
(What do you what to disprove)
that you can obtain $a\sim a$ by using the other 2 properties
lifelong dumbass
Write it formally
lifelong dumbass
I'd say that their x is arbitrary
thats fair ok
since they are trying to prove that x ~ x for all x
suppose for all $ x, \exists y $ s.t. $x \sim y$
What do these words mean in math symbols?
lifelong dumbass
But that’s neither of these 3 words
no i was trying to follow this
Aren’t we trying to write this in more detail?
I think that the OP wrote out the ||faulty|| assumption they made here in the proof
Im kinda lost on what the current goal is
wait just to ask shouldnt this be symmetric + transitive => reflexive
ok
Write out what each of those words mean in math
$x\sim y \implies y \sim x \implies x\sim x$
lifelong dumbass
Nope
Why are there 2 implications
Each of the words
Reflexive, symmetric and transitive
ok
reflexive implies that $x \sim x$, symmetric implies $x \sim y \implies y \sim x$, transitive implies $x \sim y$ and $y \sim z$ $\implies $ x \sim z$
lifelong dumbass
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Not implies, is
oh ok
Also you’re missing quantifiers
reflexive is that $x \sim x$, symmetric is $x \sim y \implies y \sim x$, transitive is $x \sim y$ and $y \sim z$ $\implies $ x \sim z$
lifelong dumbass
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ok let me add them
for an equivalence relation $R \subset X \times X$
reflexive is that $ x \sim x \forall x \in X$, symmetric is $ x \sim y \implies y \sim x \forall x, y \in X$, transitive is $x \sim y$ and $y \sim z$ $\implies $ $x \sim z \forall x,y,z \in X$
lifelong dumbass
i think
Usually we put the quantifiers before though
But that’s right
So we need to show the last 2 imply the first (or that it doesn’t imply)
ok
Notice that the last 2 statements are implications, whereas the first isn’t
They tell you more about the behaviour of relations when you pick 2 or 3 related elements
What about reflexivity?
reflexivity describes just the relation of an element with respect to itself
so
the last two are logical statements (transitive and symmetric)
whereas the first is simply an assumption you take to be true?
and without an assumption you take to be true, logical statements are meaningless?
is that the point you're getting at
Yes here
The first statement is just always true, for every x in X
We don’t need any assumptions
The other 2 tells us more if we first pick some related elements
Notably, if there’s nothing to pick, they will be vacuously true
but by picking related elements, you've already assumed reflexivity?
No I haven’t?
I can just say suppose (a, b) ∈ R
If R is symmetric then we know (b, a) ∈ R
But first I need that (a, b) ∈ R before I can use symmetric to say more
If R is reflexive then I immediately have (a, a) ∈ R
I don’t need this step
Well, if R is empty, is R symmetric?
i mean a, b don't exist
It’s a yes or no question
so yes
well theres nothing to pick so yes
What about reflexivity?
Okay, what elements are we picking in here
Like, from where do the elements that we pick come from
for the symmetric property?
Yeah
the empty set
From R
What about this? From where do we pick the elements from?
we cant pick the elements from anywhere because they don't exist because R is empty?
We’re still picking from R
There’s just nothing in R but we attempt to pick stuff from R anyway
Okay what about
Where do these elements come from
i guess we still try to pick them from R
Well, no
but why not
We don’t pick from R because we don’t need an assumption for reflexitivity
What do you even mean by elements? R is a set of ordered pairs, are your elements ordered pairs?
Yeah
Symmetric is (a, b) ∈ R => (b, a) ∈ R
Transitivity is (a, b), (b, c) ∈ R => (a, c) ∈ R
You might want to re-read this btw @still drum
i mean i think i do get it
like i understand that reflexivity is just a fact that you assume
like i think i understand what the words i said me
Write reflexivity in this way
$(a,a) \in R \implies (a,a) \in R$
lifelong dumbass
which is the same statement
ok then reflexivity is just that $ (a,a) \in R $
This is if a ~ a then a ~ a, it doesnt say that a ~ a for all a ∈ X
X
Ah
we pick a from X
But for the other ones we picked ordered pairs from R
So somehow this is different
ok
So here if R is empty then symmetric and transitive is always true
What about reflexivity
R is defined as $R \subset X \times X$
lifelong dumbass
R being empty says nothing abt X being empty
It could
but then R still wouldnt be empty
because then you could have the ordered pair $(\phi, \phi)$
No we’re asserting here that R is the empty set
lifelong dumbass
No that doesn’t work
oh
X doesn’t contain the empty set
X is the empty set
So suppose X was empty
Then when we try to find everything in X to test of (a, a) ∈ R, for a ∈ X
What happens
theres nothing to test
So it’s true
If R is empty and X is empty then it’s true that R is symmetric and transitive => R is reflexive
Well, if R and X are both empty then it’s always all 3 anyway
What if X was not empty?
if X was not empty there is actually stuff to test
So R is not…?
So R is not what
Yeah
So my mind goes to R is empty because of this
I realised that symmetric and transitive didn’t necessarily mean (a, a) ∈ R
Because what if a isn’t related to anything
What if every element in R doesn’t have a as one of it’s ordered pairs
If I find just 1 thing (call it a) in X that never appears in either entry of R, we can’t say that (a, a) ∈ R
but you also needed the other two statements to be true
I’m assuming it’s true
I’m trying to show that the implication doesn’t hold
Suppose X is any set, and R a relation on X, and R is symmetric and transitive. Does this imply R is reflexive?
So then I need to show that for any a ∈ X, I can show using the assumptions that (a, a) ∈ R
Then I get to here
If a is related to something, anything, then (a, a) is automatically in R as well
ohh
so like
suppose i had R such that
for X = {a, b, c}
R = {(a,a), (b,c), (c,b)}
then the line of logic doesnt hold because
oh
If R is transitive then (b, b) and (c, c) are in R by picking the last 2 elements in both orders and using transitivity
Then because every element of X appears in at least 1 of the pairs in R, it is true that R is also reflexive (note that we didn’t assume thing)
Well, suppose X = {a, b, c, d}
And R = {(a, a), (b, c), (c, b), (b, b), (c, c)}
Now R is transitive and symmetric
but its not reflexive
Yup
because (d,d) isnt in there
Exactly
ok that made more sense to me
.
than the example with the empty set of R
alright
im sorry
this took way longer than it should've
Yes but the empty set was a much simpler example
Once I realise the difference was in picking stuff, it turns out the empty set will work
i guess thats also fair but requires you to accept that vacuously true statements just dont matter
or rather
they do matter
but you can arbitrarily choose whether they're true or false
oh really?
This has to do with how the implication sign logic works
sorry im just trying to look this up now and misread a line on wikipedia
p => q is always true if p is always false (I think)
i mean ik it was really frustrating so
well i felt really frustrated throughout all of it (this stuff really does require patience huh)
oh i think
i realised where
i went wrong
.
That frustration is the learning part!! Embrace it!
here
this is wrong
because
instead of it should be reflexive is that $ x \sim x \forall x \in X$, symmetric is $ x \sim y \implies y \sim x \forall x, y \in X$, transitive is $x \sim y$ and $y \sim z$ $\implies $ $x \sim z \forall x,y,z \in X$
lifelong dumbass
it should be
reflexive is that $ x \sim x \forall x \in X$, symmetric is $ x \sim y \implies y \sim x \forall (x,y) \in R$, transitive is $x \sim y$ and $y \sim z$ $\implies $ $x \sim z \forall (x,y), (y,z) \in R$
lifelong dumbass
No thats the same thing
oh
Reflexivity doesn’t have an implication
Rather, it says a ∈ X => (a, a) ∈ R
Go google implication sign truth table
It always returns true when p is false
So in the case where X is empty, a ∈ X is always false
So the implication always returns true
So any relation R on an empty set X is always reflexive
That’s what I meant by the “vacuously true” message
No no put it back together and learn something new!
It do be like that
ok
like i just finished doing a bunch of exercises before this
so im already smoked
thanks again for all the help
alright ill close the channel now
.close
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yes it is cuz the negation will be always false then
not(p => q) = p and not q
so whatever q since p is false the and is false
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Okay, I have a very stupid question i need to ask. Why can i not use the concept of maxima-minima here? I just know we cant, but why not?
Please tag me
how are you planning to use the "concept of maxima-minima" an wdym by that?
I somehow had it all figured out in my head, but now that i tried to type it out, i realised that i was wrong
I was thinking of using the derivative 
brain fart
yeah derivative wrt a discrete variable is sus
.close
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what’s the intended sol?
general form of binomial expansion formula and then.. idk
find the ratio between two adjacent terms and note when it switches from >1 to <1
idk wym by that
the terms are C(9,k) 2^(9-k) (9/2)^k
find the ratio between the (k+1)st and k'th term
wait
it’s consistent?
k+1th term and kth term have a ratio?
wdym "consistent"
i never said the ratio was constant
it'll depend on k obviously
oh it’s dependent on k
i see
ratio>1 means the next term is bigger, ratio<1 means the next term is smaller
oh i see
so ur solving for ratio>1
and then you’ll get k
sub back in
thats final sol
ty
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I've been able to conclude that sum of coefficients would be 4^n. how do i proceed? i dont even fully understand the demand of the question after that
Please tag
@tranquil pine for which n is that between 4000 and 10000?
for that n, what is the largest coefficient?
n = 6
yeah, its singular, i wonder about the strangely specific range
so (1 + 3x)^6
when is (n,i) the largest?
its binomal theorem, so only positive integral powers
yes now you need to find the largest coeff in that
i hate helping other people and discovering im wrong
which you can even do by just finding all the coeffs outright
c'est la vie
i dont think thats the best approach 😦
takes about as much effort as the ratio thing
c'est un crossiant
n=6 is p low
anyway, i=3 right?
this isnt only about the binomial coefficient
the binomial coefficients are 1, 6, 15, 20, 15, 6, 1
what if i had like n=10, what can i do then?
then do the ratio thing
i hate helping other people and discovering im wrong due to a index shift or something
ie find the ratio of the k+1st term to the kth
and find at which k this ratio crosses 1
the coefficients dont contain x
that is correct
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is there a difference between ≨ and <?
No...I guess? Maybe that's why I have never seen it before
I was just looking at unicode characters for something unrelated to math, and found that
and was just curious as to why it even exists
I did some google and it say ≨ mean "less than but not equal to", kinda pointless while we have <
yeah
@silk fjord Has your question been resolved?
I mean, some people use ⊆ to mean “subset” and ⊂ for “subset but not equal to”
while other people use ⊂ to mean “subset” and ⊊ for “subset but not equal to”
so I guess ≨ exists for “completion” of possible combinations, idk if it has any real usage
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this question
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
6
1
yes
i did something like putting the value of x=5 but thats undefined
i know i have to do something to make it defined to be able to put the limits
question was not addressed to you.
indeed
try adding and subtracting 5f(5).
and grouping the terms into two pairs
jus to the numerator
yes on the numerator.
ok
i take it you understood?
yea so i can cancel out the first term
and the socond one rules out
the one after the + sign in the numerator
L'hopital
so f(5) + 5*(Lt x->5 (f(5)-f(x))/x-5)
Do you know the definition of a derivative
yes
Yes
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$$\lim_{x\to2}{(3-x)}^{\tan{(\frac{\pi}{4}x)}}$$
Koren
i don't know what to do at all,
i suppose it's related to e^lnx=x
Yes use this to rewrite your expression
$e^{\log(a^b)} = e^{b\log(a)}$
riemann
$$e^{\tan{(\frac{\pi}{4}x)} * ln(3-x)}$$
Koren
lim (e^thing) = e^(lim thing)
ok, that's still \pm\infty times 0
Yea you're not done manipulating
What else have you tried/learned
?
i don't think i learned how to do this exrecise, it's from a test from 2014 and the subjects might have changed
so i want to see which tools there are to solve it
to see if i know those
L'hopital is something that was teached every year for like 20 years in my course but this year it wasn't
so it may be it
@vivid jungle Has your question been resolved?
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The question is written as below:
A study of 55 patients with low-back pain reported that the mean duration of the pain was 17.6 months, with a standard deviation of 5.1 months. Assuming that the duration of this problem is normally distributed in the population, determine a 99% confidence interval of the mean duration of low-back pain in the population.
@kindred sail Has your question been resolved?
<@&286206848099549185>
!status
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7. None of the above
oh dear hypothesis testing
Do you know the difference between the sample variance and population variance?
yeah
Do you remember how to relate them in an unbiased way?
no
So if you have a sample variance of s^2, then your unbiased estimate of the population variance is n/(n-1) s^2
then you can just use z-scores to find the rest.
i dont know xi tho
the question didnt give the values im supposed to subtract the mean from
xi meaning $\xi$ or $x_i$?
OmnipotentEntity
the second one, not the greek letter
where x_i means the start of the interval we're seeking?
wait
given that my sample size is 55, the mean duration is 17.6 months and the standard deviation is 5.1 months, i just need to find the Z-score of the 99% confidence, and then use it to find the margin of error
and then after that i dont know what else
So the 99% confidence interval is the smallest interval that contains 99% of the probability mass of the distribution, right?
yes
0 to 0.99?
???
bruh im confused
it's ok
wait let me show my steps
uh huh
our confidence interval should always contain the mean, because that's where the most probability mass is concentrated
yeah
So our range, from (0, 1), we need to cover 50% of this, so we can have (0, 0.5) or (0.4, 0.9) or (0.2, 0.7). But which interval is uniquely situated right in the middle of the range and so covers the most mass in as small an area as possible?
id say (0.4, 0.9), if not (0, 0.5)
I'm asking about inside of the cdf interval
no i dont remember
well currently im taking grade 12 data management, i dont think i learned about CDF yet
so a normal distribution is symmetric. The mean is located at 0.5
yeah
We want to surround this as evenly as possible.
which will give the interval (0.25, 0.75)
okay
do you see why?
because of the 50% confidence
well, any of these intervals would be a 50% confidence interval.
but the (0.25, 0.75) interval is the smallest one.
you can divide 0.5 by 2 and just make the interval (0.5 - 0.25, 0.5 + 0.25)
okay
going back to my question, with 99% confidence we could say that the confidence interval is (0.005, 0.995)
so you take the edges of the range and convert it into a z-score
using the z-score table working backwards.
then using the z-score you find the interval.
hmm
when i worked on it, there was something called a critical value, and i used a t-distribution table
also by taking the edges of the range, you mean i take 0.005 and 0.995 and convert them to Z-scores, then calculate the margin of error?
and then use the margin of error to find the interval
with 55 samples you don't need to use the t-distribution, you're well estimated by a normal distribution (central limit theorem)
The switchover point is about 30 samples.
about 30?
let me show you what ive got as of now
from the looks of it the switchover point is about 17?
sorry
I went afk
30 samples
you have 55 samples in your problem which is > 30
therefore you use a regular normal distribution instead of student's-T
ok
does my interval look correct tho
let me actually work this problem through and see.
oh
no actually I can tell immediately that it's not correct.
You should get an interval of about (4, 31). @kindred sail
Obviously, you should work the problem to get more significant figures.
but you can use my estimate to check your work
can you explain your steps to getting this estimate
wait with that interval that would make the margin of error too large
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Hello. After a bunch of calc 2, I forgot how to manipulate algebraically to get a remarkable limit
use e^ln
i was about to reply but then noticed you greeted with "hello gentlemen"
or defn of e
i wonder if that means you only want men replying or if this was unintentional
@covert girder
Unintentional.
ok then you could simply erase the word "gentlemen"
a cooler method 😎
You got it
and not leave a girl wondering if she could even engage
Math has no gender
But I got it
Just my way of addressing, sexist or not, I apologise
the inside stuff rewrites as 1 + 1/(3x+1)
so you want this raised to the power of 3x+1 to set up your e
yeah, consider changing it. even "hello everyone" has a lot less risk of misread
So as far as I see I got 3 ways of solving it
the pro gamer move is to write $x+1 = (3x+1)\cdot\frac{x+1}{3x+1}$
Ann
For sure. Don't want to cause trouble in a community I've been lurking for years
the defn of e 🔥 🔥
not wrong😭
Is that Taylor or what, seems similar
but TheVibe is jking here
not that one
limit of (1+1/n)^n at infinity
Not that useful in this casexd
that was mclaurin (taylor) expansion ye
in your case, 3x+1 plays the role of n
I think I got it, no?
Yup
Uuuu, well this is a pre uni test
🔥 🥳
yup
Thanks everyone! I'll make sure to follow a more diverse etiquette
What a nice solution
It's how it was defined for me, but ye we do a lil trollin
a lil tomfoolery
Thanks for the laughs and the help, all!
Saving my calc as always
Have a nice one!
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im about to stress TF out
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whoops
cut off is just "nt" ive redone this type of problem like 30 times now and i really need some help
ive tried calculator and multiple AI but i just cannot do it im stressing out HARD
please....can anyone help
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hey, my specialist gave me another problem, how do i approach it
@jade iris Has your question been resolved?
@jade iris Has your question been resolved?
Not 100% certain this is the correct solution, but first I’d recommend playing around with small values of a and b, evaluating a#b as you go, to try and find a pattern in what a#b is
From this, you can deduce that a#0=a, so a#1=a+1 (for a>0) and a#2=a+2 (for a>1). From this, a logical conjecture would be that a#b=a+b (which would work nicely with the value you want to evaluate) as 1#(2#(…(13#14)…)) is just the sum of the first 14 positive integers
Prove that the operator # is commutative and associative
Then you can do the calculations from left to right
And ignore all the parentheses
3#1 = 2
ok i proved its commutative and associative but how do i evaluate the expressions. It's still so much work
here's an additional hint: # = XOR
let's see if i write it like this, would u understand
3 # 1 = (convert to binary) 11 # 01 = 10 = (convert back to decimal) 2
but how does the operation # have anything to do with binary
this is so complicated to explain gicahpfcrvnjkra
how did you know it was xor
you can explain it however you want
out of curiousity, did you chatgpt this?
my specialist will not accept chatgpt answers 😠
no
i dont even have money to chatgpt
smh
wouldn't doubt it
it's gotten good enough to answer these types of questions but its explanations are quite awful
can someone please just explain how you get to xor
that is so confusing
i can try and solve it from there then
and no ai please
Now with better audio quality.
Some interesting problems:
https://www.hackerrank.com/contests/5-days-of-game-theory/challenges/tower-breakers-2
https://www.hackerrank.com/contests/5-days-of-game-theory/challenges/tower-breakers-3
https://www.hackerrank.com/contests/5-days-of-game-theory/challenges/a-chessboard-game
it's not a coincidence
ty!! i put this into my ai and it also showed the same vid, must be right then
damn
honestly the # = XOR guess took me a solid 30 minutes
to figure out
also didnt know ai now can generate correct https address lol
the ones that have been specifically programmed to search for sources can
i dont think a genai with no help could
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help
the red part is shaded only right
or am i tripping
<@&286206848099549185>
havent done this in so long
!15m
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(ignore the shade)
Yea so that's the shaded part
Where else can u see shaded marks or whtever u call them
Sorry
I misunderstood ur question
U r ryt
Red is shaded
Along with this part
Uhh, I need to learn something here, what's the relation between set A and A'?
A' means U-A
Everything except A
its that without the middle no?
Danm, that's new to me, I have never been taught that, thanks
Lemme walk u through this
So here everything except The marked part is E'
Do we agree
ye
this is DUE'
the ones not shaded
Yea
what is happening?
yup thx
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What is commutative binary operation?
,w commutative binary operation

worth a shot i guess
G×G-->G
In mathematics, a binary operation is commutative if changing the order of the operands does not change the result. It is a fundamental property of many binary operations, and many mathematical proofs depend on it. Perhaps most familiar as a property of arithmetic, e.g. "3 + 4 = 4 + 3" or "2 × 5 = 5 × 2", the property can also be used in more ...
So A×A will have 25 elements
To 5 elements
Now my doubt is how can I make map?
And the map should be symmetric?
to make a binary operation, it suffices to specify what's the output for every possible pair of inputs
The output will be like (a,b) form
The diagonal elements will have choices
I found something best explanation
Wow brilliant people!! Explained easily hurrayy!!! Thanks everyone
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how do we solve min max problems?
What are its steps
be more specific? what problem
min max word problems where you need to find its maximum/ minimum extrema
find the minimum or maximum given an equation?
do you have a specific example
differentiate it. when the derivative is 0, check if its a min or max. for all points where derivative is 0
You mean application of derivatives problem?
some points are neither, u can find out by checking second derivative or a sketch
@covert flower Has your question been resolved?
Yea one sec
this one
differentiate it. thats what they did when they found S'. they set that =0. and found that is when r=cbrt(250/pi). they put that into S'' to find out that its >0. which implies that its a maximum. in this case, maximum volume.
S' = 0 denotes the change is zero. so it can be a maximum point, minimum point of inflexion point
with the use of the second derivative we can find out which it is
S''=0, weird behavior
S'' >0 minimum
S'' < 0 maximum
S"=0 isn't always inflexion point tho
indeed, you have to study the sign of f'' in the neighborhood of the point, if it changes at the point then it is
oh sorry. what else can it be
@covert flower Has your question been resolved?
it can be something, you can take x^4/12 and see that the second derivative is x^2 and so indeed 0 at x=0 but its not changing convexity cuz it does not changes sign
f'' = 0 is a neccessary condition for an inflexion point but its not sufficient
sorry I was outside 😭
let me read
thanks
welcome on the server btw
thanks
I’m confused
what the question is asking
save me
In order to do this question what do I need to know
This is basically word problems
esthesia wrote the method here, we were just talking about the case where f'' is equal to zero where this is a case you can't say its a max or a min. it probably won't happen in your exercices since you're asked to find a min or a max
yakuuu
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help please
This problem relates to euler "candy division problem"
Which is a really powerful tool when it comes to counting solutions for sums
You should look it up on Google, tho. It's quite a lot
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Hello, so the dunford decomposition of a endomorphisme u is the unique couple (d,n) such that nd=dn and u=d+n where d is diagonalizable and n is nilpotent , I have proven the existence of d and n that satisfy this property and I have proven that they are a polynomials of u .
in the proof of the uniqness we have assumed that if any other couple (d',n') exists they must also be a polynomial of u, without providing any proof of it !
So my question is:
is the uniqness true only if the couples are a polynomial of u or can one prove that (d',n') must be a polynomial of u ?
if you found that d and n are polynomials of u, when you take another couple that verifies the original properties, they too will be polynomials of u
How so ?
Well by doing what you did for d and n
because the uniqness is always true that's for sure when it exists
I constructed d and n from projections on the characteristic spaces
yes
I can't do that for d' and n'!
well you have d' + n
oops
you have d' + n' = u because d' n' = n' d' you have d' u = u d', same for n', and since d and n are polynomials of u, d' and n' commute with d and n
and i think that's all you need
you dont need that they are polynomials of u actually, just need the fact that they commute
(and yeah im sorry i just didnt remember the construction of d and n)
dunford decomp was a while ago
Does that answer your question?
yeah that's much better actually
ok great:)
The uniqueness of the Dunford decomposition does not require the assumption that
𝑑 and n are polynomials in 𝑢.
Even if another decomposition
(𝑑′,𝑛′) is given with the same properties (commuting, one diagonalizable, one nilpotent), it must be equal to the original one. So:
You don’t need to assume
𝑑′,𝑛′∈𝐾[𝑢]— the uniqueness proof works without that
the whole point of the polynomial of u was to show the commutivity
yeah i see that now
you can use it to show it yes
not required tho
yeah thnx
:)
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how can i make the construction of this triangle using geogebra?
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How do i solve this
What is your grade ?
Why does that matter
No just asking
@normal shuttle Has your question been resolved?
What if 12 is the measurement of something else
Its not i asked
My teacher said it wasnt
He said its a typo
I also have the answer but that doesnt make sense to me
This might jusy be wrong 💀
I dont think thats how euclidian works
My intuition says that AHB and CHB are similar triangles, but I can't really prove it. Edit* I'm so totally incredibly wrong
Dang this makes sense
Okay u see triangle ACD and trainfle ABC r congruent ryt?
Yeah
Uhmm
Ryt?
Lol
Taking different approach
BHC and ABC
I declare it to be flawed
Nah it's prolly possible the 4 person u met rnt qualified enough
And me but lets try either way
Yes sir
BHC and ABC share two angles no?
U can prove that BHC is congruent to ABC
It is 90
rectangle
Rectangle has 4 90s bro
Oh okay so they r congruent
So u could say that
<HBC=<BAH
Yeah triangle BAH AND BHC
are we still on this question?
Yes
U can find that those two r similar ryt?
one hypotenuse AC=13 one hypothenuse AB other hypotenuse BC
Pythagoras
write down three equations
two of them involves BH
cancel the BH out
I had a stroke reading this
compare with the third
Compare AB and BC with AC?