#help-27
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Bounded by the curve means that its either below or above, depending if its below or above the x axis
x axis being y = 0
So what justifies that we integrate
Yes
then it says to do the the x-axis? meaning?
Whats x axis
and the line π₯=4 meaning this?
Yes
0 1 2 3 4 5
Can you show the actual question
More generally
Is it this
Amazing lack of parenthesis
Then, find the area of the region bounded by the curve, the x-axis, and the line π₯=4.
i think its the commas, i think they mean just two methods, the x-axis and the line x = 4.
not that by the curve AND the x-axis AND the line x =4
cuz obvs that bounded by the curve is till the x-axis and the line x = 4 no?
When you integrate you calculate the area between the curve of a function and the x axis, thats why they talk about x axis
no, it's one area. the curves that bound it are: the curve 1/(1-x), the curve y=0, and the curve x=4
Also, it is starting to 0 because it is where the function meets x axis
and not like this?
red for find the area of the region bounded by the curve, the x-axis
and green for the area of the region bounded by line π₯=4
?
I JUST read it again
i see what you mean
clearly
thanks!
SMH π€¦ββοΈ kek
Both are area of region bounded by x axis and curve, you just stop at different line x = smth
you're welcome
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yes
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\textbf{Lemma 6.3:} \textbf{$\forall$ ordinals $\alpha$, if $b \in \alpha$, $b$ is an ordinal.} \ \
\textit{Proof:} We first check if $b$ is transitive. Choose any $z \in y$ and $y \in b$. We want to show $z \in b$. Since $b \in \alpha$ and $y \in b$, $y \in \alpha$ since $\alpha$ is transitive. Since $y \in \alpha$, and $z \in y$, then $z \in \alpha$, since $\alpha$ is transitive. Thus ${z, y, b} \subseteq \alpha$. Because elements of $\alpha$ are transitive, and we have $z\in y$ and $y \in b$, we get $z \in b$. So $b$ is transitive.
\\
$\in$ is a strict well-order on the elements of $b$. Since $b \in \alpha$, and $\alpha$ is transitive, $b \subseteq a$. Since $\in$ induces a strict well order on the elements of $\alpha$, it clearly induces a strict well order on the elements of $b$. $\blacksquare$
toast
hello i have writtent his proof down in my notes
i think i mightve missed some parts of it
specifically the last sentence of the first paragraph
i understand everything up to why can we now assume z in y and y in b => z in b?
oh
hm
?
<@&268886789983436800>
<@&286206848099549185>
what
.
beyond my paygrade
i dont fully understand the portion where its saying because elements of alpha are transitive
Optional btw
kinda hard lowkey
I think i get it
So because alpha is well ordered, it must have strict well ordering so we know z, y, b are elements of alpha and we also know z \in y and y \in b Then because elements of alpha are well ordered, z must be in b because strict well-orders are transitive
can someone confirm my understanding ^
yeah that looks correct
honestly props to your for figuring that out
i didnt even have an idea how to do it
eh its just set theory and following directions
i confused alpha being transitive
and transitivty of well orders
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In this Venn diagram, what does U at the top right mean?
the universal set
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does it matter where the limit comes from in these types of question?
what do you mean by where does limit come from
how
Because it is the primary thing that will decide what sign we get
like the lim->5+/-
For eg question 32 of the image
it does
Since it is 3-, we get a negative sign
Since it is odd power the negative sign stays
Hence the limit approachs $-\infty$
Itsuki
so if its even power, and the sign is negative it becomes positive?
Exactly!
Nope no exceptions you should worry about for now
so if its x->0-, per say it becomes positive too right
oh
Just less than zero
For a reference something like -0.00000000...
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please explain this to me
go step by step
can you tell me what you've tried so far?
!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
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okay so I simplified the given term and got (xy)^2, so i want to know whats the thinking process that goes in your mind when you try to find maximum value of (xy)^2 when youre given a restricted domain. I know the answer, but i want to develop my own thinking to it, but im struggling to i would appreciate if you were to guide me to think for it
Its a well known trick that when x^2+y^2=1, you can substitute x=cos theta, y=sin theta for some theta
so we do just that
and then (x^2y^2=\cos^2\theta\sin^2\theta=(\frac12\sin(2\theta))^2)
Richard Liu
and (\sin(2\theta)) is at most 1
Richard Liu
so maximum is (1/2)^2=1/4
alternately you can use AM-GM
yh
oh yes, one way to solve this is by trigonometry. that clears it up, thanks for the assist
i havent studied AM-GM yet actually
will be learning it very soon though
if you are done with the thread and do not have any other query, you can close it by typing .close.
Closing solved threads/help channels helps people know that the query is solved and avoid the need to ask if you still need help
oh yea, thanks for the reminder
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Prove that the collection of all successor ordinals is not a set.
maybe the idea is to create an isomorphism between ordinals and successor ordinals, because we have already proven the fact that all ordinals are not a set, and we can show that theres a 1-1 mapping between oridnals and successor ordinals, then the set of successor ordinals is nto a set?
I thinkt his idea is right but I'm not sure how to represent it rigorously with the axioms we have discussed in class
Set Existence
Axiom of Extensionality
Pairing Axiom
Separation Scheme
Union Axiom
Axiom of Infinity
Induction Scheme
\textbf{Prove that the collection of all successor ordinals is not a set.}
\\
Assume by way of contradiction that the collection of all successor ordinals is a set, denote this set by $SO$. Observe by a theorem, since $SO$ is a set of ordinals, then $\bigcup SO$ is also a set of ordinals.
toast
my next argument was to show that USO = ON
(i.e collection of all ordinals)
π
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can i get any tips regarding how to approach this problem? im running in a circle tryin to susbtitue value by sum and product, although not getting a clear solution as given in the options. I would apprieciate a small hint on how to proceed with this
sum of roots, product of roots?
(Hint)
running into a circle with that, ending up with the same equation with x = alpha
Oh you're asking for tips
Manipulation
I would appreciate both tbh
Did you try to solve it using the quadratic formula?
okay so, i basically did x = beta, in the given equation. and subsituted value (in terms of alpha) for beta^2 and left beta as it is, and it gave a much more complicated expression than in the option
I did, got the roots but the answer begs in term of alpha does it not?
verifying each option 1 by 1 is unusually tedious and im sure theres a more clever way to solve this
so viete's identity stated this
$\begin{cases} x_1 + x_2 = \frac{-b}{a} \ x_1x_2 = \frac{c}{a} \end{cases}$
1 divided by 0 equals Infinity
yes
so if we substitue $x_1 = \alpha$
1 divided by 0 equals Infinity
then we can solve for $x_2$
1 divided by 0 equals Infinity
i did, but the equation isnt matching with the options. I will redo it rn in case of any errors though
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Show your work, and if possible, explain where you are stuck.
show us your work
gimme a minute
Using only sum of the roots to get this relation, substituting Beta into the product gives the equation we've started with (4x^2 + 2x - 1)
1 divided by 0 equals Infinity
yes
substitute into $\alpha\beta = \frac{-1}{4}$
1 divided by 0 equals Infinity
checking the options one by one is the way here ig unless there's a trick i cant find
will only give us the initial equation 4x^2 + 2x - 1 with x = alpha as I have stated before
Ig there's some manipulation we're not able to find
i don't think so
oof, I guess thats the only way
just try substituting $\beta = \frac{-1}{2} - \alpha$
1 divided by 0 equals Infinity
into the product $\alpha\beta$
lemme try again, mightve did erorr
1 divided by 0 equals Infinity
you'll get a quadratic of $\alpha$ if you did it correctly
1 divided by 0 equals Infinity
It's the same quadratic
and then what?
oh wait rlly?
well then solve for $x$ directly
1 divided by 0 equals Infinity
and then plug and check
Yeah
thats what ive said, like 3 times now
But that's not fun
thats the sad part about this problem
ahem
ig no other way
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I tried completing the square
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β Original question: #help-27 message
and?
(2x+1/2)Β² = 5/4
1 divided by 0 equals Infinity
I was finding a manipulation
hold up
lowkey no other way, it all leads back to it
lemme try smth rq if it works
aight
Manipulation
enlighten me
i am looking
π€―
Waitπ
tbh substituting's the deal for me
since it's multiple choice
why can't you just find the numbers directly
okay- π
it's multiple choice, what's the deal?
ofc we have, but if theres a manipulation we can use to get answer more quickly then why shy away from utlising it?
yea ik
but finding the manipulation takes more time than just solving directly
by the time people are helping, if you did solve the numbers directly then you would've done
but also reduces number of errors and expands your thinking capacity when given similar proble
you allowed to use a calculator?
nope
except im solving dis at the comfort of my home rn, and if a manipulation exists lemme find it
no other way
Yk what's the other way
staring at the options?
Equating this with options
ooh that's genius
And checking the value of aplha
a^2 = -1/2 - a
At least it's faster
Nop doesn't fit
a = -1/2 so definitely not
Option 2 should fit
It gives one root same
4a^2 + 3a = -1/2 - a
gives a cubic?
Yeah both roots same
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
So what, didn't they teach you to divide
bluds lets quit
also really there's really no way to get a cubic in here
you quit alone by yourself
Fastest method we found to solve this problem is using options π
the approach might be lying in this spaghetti π₯
impawssible without solving directly
Even if you go directly it's kinda hard
I think the trick is to use the options only
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can someone give me a hint for part B please
what did you get for a?
not possible
I figured for part b of the question I could place this piece so that it is on 3 black tile and the other one on 3 white tiles than that would cancel out
Well, you now think it's possible, right? So try to construct an example
I am. I cannot seem to find a way to get it to work
I made little cutouts and am trying to arrange them
hmmmm how would they fit together then?
they dont have to be immediately next to each other
Maybe try starting with this configuration since both Ts cover the same number of black and white tiles
It shouldn't be too difficult
what tool are you using for that?
I just found some random website https://toytheater.com/tetromino/
Found a solution yet?
Try placing the straights and squares first
The Ls and Ss can combine to make a lot of different shapes so they are easiest to place last, filling whatever area is left
I always end up with one piece not fitting
Try with this
I've done it four times now, including once with this
finally got it
that was not fun
just felt like guessing randomly until I got it right
thanks
I don't know why I struggle so much with arranging shapes
I say that and then i did this in 30s
anyway, thanks @drifting sierra
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How to do 19a and b
Just start from (0,1) and follow flow lines
It's a sketch so not meant to be super precise
fr
What's already drawn is fairly good I think
Same process but start from (-3,0)
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Trying to find the value of X, can this be done? If so how can I solve it?
Thats what Iβm trying to find
like i mean
If it helps both lines are 252
like idk what x is pointing to
are we assuming this
yes
right angle on the bottom
yes tangent
Wait
ok so x = 252 tan 9
So its tan
Thanks guys
Yeah its a right angle
I have the values over the original image if this helps
Yea
I accidentally put 252 on the top one instead of the bottom and forgot to erase
Its still tan tho right?
Thanks guys
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wait what
no it's not a right angle
this triangle isnt even possible
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Is my math right for this? I still gotta graph
Which I'm probably gonna need help with
,rccw
poor notation. in both questions you seem to write f(x) = transformed function before the g(x) = transformed function final answer.
I'm confused
look at your own work, specifically the last two lines of each question
flips x-coordinate, not x-axis
and that would be flipping across the y-axis
that part is correct. what is dubious here is misrepresenting f(x)
What should it really be
since |-2x + 3| - 4 is already the transformed function, it can't be f(x) any more
I guess that was just me showing my work then changing it to g(x) to box in
if you had put f(**-**x) instead of f(x), I would have accepted it
but then you would be saying that f(x) is now this new function. which isn't the case
Hm I don't think I've ever had, wasnt taught to write it that way
I just know the formula mentally
q6
I can't say what it really is
I'm using q6 as an example, but it applies to both questions shown in the image
So because its a reflection over the y it's -x
the x is negative because it's the transformation you have made
you are defining a new function, g(x), as the transformed version of f(x)
the transformation is a reflection over the y-axis, which is f(-x)
hence, g(x) := f(-x)
I guess I'm confused why the x is negative because I thought you were just referring to like the formula for a reflection
I mean, you went from |2x + 3| - 4 to |**-**2x + 3| - 4. how?
if you can tell me how and why you did this, then there is a high chance you have answered your own question.
I made the 2 negative bc that's the rule for a y reflection
what is the rule for a reflection over the y-axis?
,rcw
Make the x negative
there, see? f(x) becomes f(-x)
g(x) is the transformed version of f(x), and the transformation is f(-x). so g(x) := f(-x)
it's better to write it something like this to illustrate the exact transformations first
then you can do your algebra as necessary
In my examples I just go straight to g(x) so
I guess I've never done it bc I didn't know I should
Are my answers okay tho?
6 is fine, haven't seen 7, sec
Alright
And I need help with the graphing ig, someone tried but I was confused
I also lost the chat bc I couldn't graph when they were helping
7 is also correct
if you are in doubt about how to graph these, perhaps start with the basic f(x) = |x|
Thank you, I think 2 and 4 are too
No worries I'm sorry
So like at (0, 0) right
nt sure what you mean by at (0,0) but perhaps you can graph what you mean?
yes
you can then transform this graph into what you need in two ways
first, if you are not confident, you can graph the given function, then transform the given function into your answer function. if the graphs of the given and answer functions match the transformation you were asked of (eg. q6 given and answer being mirrored across the y-axis), then you can be sure you are right
if you are confident though, you can graph your answer function directly
I also have my graph calc I just don't know what to look at / type on my y's
honestly just use Demos
Desmos*
are you not allowed to use Desmos or Geogebra or anything like that?
what model do you use? I am only familiar with the Ti-nspire
I suppose each y is a function?
if so, type in your original function as y_1 (the given function) and your answer as y_2
,rcw
So then what points should I be graphing for what
Sorry it was meant to send under that
does your calculator tell you which graph is y_2?
oh it does. then you know you put your answer function as y_2. so graph y_2.
look at the graph
Yeah, cant use on test tho
it's a V shape
some y-values would be mapped to twice
OP wants familiarity on tests
Like me graph these
let's answer her question first
What's OP
This is what I get from graphing the points
I just graphed what the graph will fit and what it showed me with out scrolling
obviously the graph isn't split though, so you can join the two pieces by extending them
(works because both pieces are straight lines. does not work otherwise!)
the cheap way is to just extend the two straight lines downwards
the proper way is to find the minimum point of this graph
What should I do
I've given you two answers to that question
I guess I meant if you were me
if it were me I'd do away with these points and graph the function just using the special points (intercepts and min point). if it were me in exactly this situation, since the points are alrd there, I'd just find the min point. or I'd just extend downwards if I was asked to sketch
the best option for you is to find the min point
What is a min point
minimum point
notice that the graph never goes under a particular y-value. that point is the minimum point
But if its not going under a particular y value how is there a min point
why would there be no min point if the graph does not go under a specific value (i.e, has a minimum)?
for instance, if I say, the volume of water in a tank will never drop under 10 liters, surely there's a minimum volume of water here?
I just thought then there would be multiple min points
not for an absolute value function. you'll meet minima and maxima in later math
no, you've drawn both the original and transformed functions here when you are only asked for the transformed version, but the transformed version is correct
but as a guide for yourself, it is fine
I was taught to draw both so I did
normally if you're not told to graph both, never graph both. if you have to graph both, clearly indicate the original and transformed functions
Maybe not taught but helps me since we do it for like f(x) = |x|
if I was an examiner and I was an asshole I could look at this and ask you, "which is the transformed function?". or worse, I can purposely pick the wrong function as the transformed function and dock you marks
never give a pedantic ass a chance to dock marks
since you already marked the original function as f(x) and the transformed function as g(x), just note the left graph as f(x) and the right one as g(x)
I think I can
Thank you
I just realized we have an unexpected mutual
Finished
mhm
looks ok
yeah experiment
vary something and observe the new graph
there are only four parameters to remember
af(bx - c) + d
and then from here you can easily divide them into two categories
first, whether the parameter affects the input or the output.
a and d both affect the output of the function (a multiplies the result of f(x), d is added to the result of f(x)), while b and c both affect the input (b is multiplied with x, c added to or subtracted from x)
parameters affecting the output of the function affect its graph vertically (memory tip: output = y, y = vertical), while those affecting the input affect its graph horizontally (input = x, x = horizontal)
second, whether the parameter is a multiplier or an addition
a and b are multipliers, hence they scale the function by some amount. c and d are additions/subtractions, hence they shift the function by some amount
scaling parameters stretch/compress the graph of a function, whereas shifting parameters, well, shift/translate the graph
that's how I see function transformations
Ahhh
hope that helps
if you can and want to memorize, you could I suppose, but I am bad at memory and as a teacher I don't encourage rote memorization anyway
Well I have a test tmmr and transformations are apart of it so I need to know the formulas to solve
fun fact! memorizing is not the only way to know stuff :D
but that's besides the point Ig
anything else?
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I found the formula for power spectral density
KirbySnack
Can someone explain to me what this means?
Also
It says that for periodic sequences
KirbySnack
Can someone explain to me intuitively what the first formula is and how I should interpret it in the periodic one?
<@&286206848099549185>
I can't explain the formula due to not knowing it or any of the context, but what is X(-, -)?
Wait
since you're taking a norm/absolute value and squaring, I'm guessing it's like a vector's length?
but then what are its inputs
is the Fourier transform of the signal observed only on a finite window of length
is nu the signal and N its length?
alee
Yes
ahhh, so it's almost like an average
square their sum's absolute value and divide by the number of terms
it is the Fourier transform of the finite portion of the signal
i mean this
@jagged harbor so now can you explain pls
I don't care about the proof
Someone can explain the concept to me in a way that's easy to grasp, even without having to do a lot of calculations or memorize formulas. It should make me think, "Oh, okay, now it makes sense.
I can't, I can only say 2N+1 is the number of terms in this sum and you're dividing by 2N+1 to get some kind of average. I think it's more like variance?
I'm trying to be just wrong enough so someone who knows better corrects it lmao
wait
variance measures how much the signal disperses over time around the mean
in this case the power spectral density measures how that power/variance is distributed across frequencies
<@&286206848099549185>
<@&268886789983436800>
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β Original question: #help-27 message
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i think they got hacked
not uncommon occurrence 
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Hello if $A \cap \emptyset$ would the result be
PainAndLight
empty set
-
$A \cap \emptyset = \emptyset$ ?
-
$A \cap \emptyset = {\emptyset}$ ?
-
$A \cap \emptyset = \emptyset = {\emptyset}$ ?
PainAndLight
option 1.
but isnt $\emptyset = {\emptyset}$?
PainAndLight
no.
They're different
i remember talking about that...
an empty set is, well, empty.
the one on the right is the set containing \emptyset, so that set has 1 element.
more specifically, the set on the left here has cardinality or order 0, while the one on the right has cardinality or order 1.
but isnt it stated that every set contains atleast the emptyset?
the empty set is a subset of every set, not an element.
whats the difference between subset and beign element of (have been asking this for the last days, but didnt try to find an answer yet)
a subset of a set is a set containing the elements of another set. an element of a set is a member of that set.
I got confused and was wondering what a beign element was 
I'm fluent in typos π
so one looks like a member the other one is the member
er.... what exactly do you mean here?
forgot that? idk
Suppose you have set A as ${1,2,3}$ and set B as ${1,2}$, we would say B is a subset of A
MxRgD
yes
building off MxR's example, 1, 2, 3 are elements of A (with 1, 2 also being elements of B).
$\emptyset$ and ${\emptyset}$ are not the same.
$\emptyset$ is the set containing nothing.
${\emptyset}$ is the set containing the emptyset.
Pfhrohug
maybe im thinking simple rn but wouldnt that mean $\subseteq = \in$ in this case
no.
PainAndLight
They are different
still no.
ok this is really weird to grasp
subset-superset relationships are relationships between sets.
elementship is a relationship between a value and a set.
but ill accept it
No. $A \subseteq B$ means $\forall; a \in A.; a \in B$.
Pfhrohug
For example ${1,2,3,4,5} \subseteq \mathbb{Z}$. And $2 \in \mathbb{Z}$.
Pfhrohug
PainAndLight
a special set, namely ${ }$.
that contains no elements
\emptyset is the symbol for "the set containing nothing".
it is not the symbol for "nothing".
trilunar arithmetic (Columbina)
like A can be a symbol for a set
and I suppose some syllabi really do use {} as an alternative to \emptyset.
it can be any arbitary letter you want to reperesent a set
and $A = {\emptyset}$ would be the set a containing no Elements? or an set containing the emptyset
there's special ones like the set of natural numbers which is denoted as $\mathbb{N}$
a set containing the empty set.
A itself would therefore have one element - the empty set.
$A = {\emptyset}$ is the set containing $\emptyset$.
REMEMBER $\emptyset$ IS SOMETHING
so A is not empty.
Pfhrohug
It's not empty!
since two Helpfuls are here, I'll step back. good luck OP!
So I would have a basket with no elements, and $\emptyset$ is not even having the basket
PainAndLight
$\emptyset$ is a set.
$\emptyset$ is empty.
${}$ is a set.
${}$ is empty.
${\emptyset}$ is a non-empty set containing exactly $\emptyset$.
Pfhrohug
ya
as one helpful mentioned, the empty set is a BASKET with nothing in it
it is still something
No. ${}$ is the basket. ${A}$ is a basket containing A. ${\emptyset}$ is a basket containing an empty basket
Pfhrohug
$\emptyset$ is the empty basket
1 divided by 0 equals Infinity
so ${\emptyset} = 0$ since we also have 0 to say I dont have anything on my bank account and saying $\emptyset$ is like saying i dont even have a bank account
bruh
no but you can say the cardinality of the empty set is 0
PainAndLight
oh
good image illustration 
alternatively, {\emptyset}.
{} is an empty basket.
{A} is a basket containing A.
{{}} is a basket containing an empty basket.
$\emptyset$ is not "nothing". It's an empty set.
Pfhrohug

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Can someone review my proof?
I can't tell if im smoking or not
oops
Consider the 'induced structure' $(Y, \epsilon)$, i.e., for all $a, b \in Y$
\begin{center}
$(Y,\epsilon) \models a = b$ if and only if $a =b$ \
$(Y, \epsilon) \models a \in b$ if and only if $a \in b$.
\end{center}
\\
\subsection{Problem 5:} \textbf{Suppose $X$ is a transitive set and let $(X, \epsilon)$ be the structure induced by $\epsilon$ (see HW #3).
In the verifications of a), b), clearly indicate where the transitivity of $X$ is used.}
\\
\textbf{a) Prove that for all $a, b \in X$, $(X, \epsilon) \models b = \bigcup a$ if and only if $b = \bigcup a$}
\\
An equivalent statement would be $(\forall c \in X)( c \in \bigcup a \iff c \in b) \iff \forall c( c \in \bigcup a \iff c \in b)$
\\
$(\implies)$ Assume that $(\forall c \in X)(c \in \bigcup a \iff c \in b)$ $()$. We want to prove $\forall c(c \in \bigcup a \iff c \in b)$. We know that $c \in b$ and $b \in X$. Then by transitivity of $X$, $c \in X$. Then by $()$, $c \in \bigcup a$. Conversely, we know $c \in \bigcup a$. This means there exists some $x \in X$ such that $x \in a$ and $c \in x$. But because $X$ is transitive, $c \in a$. We also know that $a \in X$, so $c \in X$ by transitivity of $X$ again. Then by $()$, $c \in b$.
\\
$(\impliedby)$ Assume $\forall c (c \in \bigcup a \iff c\in b)$. Take any $c \in X$. Then $c \in \bigcup a \iff c \in b$ by $()$ is trivially true. $\blacksquare$
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bruh ok
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Consider the 'induced structure' $(Y, \epsilon)$, i.e., for all $a, b \in Y$
\begin{center}
$(Y,\epsilon) \models a = b$ if and only if $a =b$
$(Y, \epsilon) \models a \in b$ if and only if $a \in b$.
\end{center}
\
\subsection{Problem 5:} \textbf{Suppose $X$ is a transitive set and let $(X, \epsilon)$ be the structure induced by $\epsilon$ (see HW #3).
In the verifications of a), b), clearly indicate where the transitivity of $X$ is used.}
\
\textbf{a) Prove that for all $a, b \in X$, $(X, \epsilon) \models b = \bigcup a$ if and only if $b = \bigcup a$}
\
An equivalent statement would be $(\forall c \in X)( c \in \bigcup a \iff c \in b) \iff \forall c( c \in \bigcup a \iff c \in b)$
\
$(\implies)$ Assume that $(\forall c \in X)(c \in \bigcup a \iff c \in b)$ $()$. We want to prove $\forall c(c \in \bigcup a \iff c \in b)$. We know that $c \in b$ and $b \in X$. Then by transitivity of $X$, $c \in X$. Then by $()$, $c \in \bigcup a$. Conversely, we know $c \in \bigcup a$. This means there exists some $x \in X$ such that $x \in a$ and $c \in x$. But because $X$ is transitive, $c \in a$. We also know that $a \in X$, so $c \in X$ by transitivity of $X$ again. Then by $()$, $c \in b$.
\
$(\impliedby)$ Assume $\forall c (c \in \bigcup a \iff c\in b)$. Take any $c \in X$. Then $c \in \bigcup a \iff c \in b$ by $()$ is trivially true. $\blacksquare$
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Would be helpful to send a picture of the original problem, cuz I'm slightly confused by what's going on
Wait this is the same problem as #help-44ο½stanley-π²-v2-dans
Why are you reposting it here
<@&268886789983436800> you guys should probably take a look at this
what the blud
huh
Huh who pinged
sup dude, welcome to mathcord,
can you confirm you're not a bot in some way?
can you say ooga booga?
In the meantime I am going to close this thread since it doesn't seem to have been started in good faith, and the OP is gone anyway.
.clos
πΏ
.close
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i wanted them to say ooga booga
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How difficult (from 1 to 5) would you rate this question? Just for curiosity
And can you confirm the solutions are $z = x \pm i e^x$, with $x \in \mathbb{R}$?
Alberto Z.
what is a 1 and what is a 5 though
1: needlessly tedious
difficulty wise it's easy with no difficult insights required, just standard manipulations
looks like a problem brushing on every concept
replace exp(i pi/2) with i
although easy
z - bar(z) = 2*Im(z)
rate it
and the rhs is a real number?
I'm getting y^2=e^(2x) for z=x+iy, so looks about right
@mystic scarab Has your question been resolved?
Lol true, 1: easy, 5:difficult

that's not what i meant
what do you consider difficult
for the average highschooler, this might be the hardest question they've ever seen
but for others, this might be a completely trivial question
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.close
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,That was exactly my intention, the big number such as 2023 was to "scary" and force the student to think deeply
I invented that exercise for a student doing the first year of uni
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how do i derive this function?
im confused with the bracket
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
2(b - 1) is effectively a constant
is it not -2 * (b-1) * x?
yes i guess
b is just a number
basically
is that what u mean
yes
yes so
wait do i just multiply with the number before the bracket and the one after the bracket
generally
like -2 timest he bracket and x times the bracket
the order doesnt matter it's commutative
also i ended up with x^2 - b/2 + 1/2 = 0
is this correct
yes
you shouldn't have an x^2
oh
my god
yo
im fried
why is this happening i dont undesrtand
4x - 2b + 2 + 2b = 4x + 2 
i keep getitng mistakes like these even in the exam
thats what i got...
,w differentiate w.r.t. x 2x^2 - 2(b - 1)x + 2b
so yeah
actually i dont
so
arent you supposed to put it into vertex form
well isnt it easier if you do
ive never learned it
idk how the derivative finds the vertex
the vertex is just the extreme points
ur right maybe im the fried one
so
solve what you get for 0 to find extrema
then plug back into original equation for an inequality in b
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the red are my notes while the black is from the question itself. I solved this problem before but now i cant even remember what i did to get the answer.
@upbeat marsh Has your question been resolved?
@upbeat marsh Has your question been resolved?
@upbeat marsh Has your question been resolved?
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$\prod_{i=1}^n i = n!$
rafael bombelli
$\prod_{i=inf}^n i = n!$
rafael bombelli
Hi is there anything you need help with?
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Factorial for n β₯ 1
i meant this one
Clearly n=f=1 or n=f=-1, but since (-1)! is undefined, n=f=i=1
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Hi
depends what you're being asked to do with this
then you walk away
Solve what
How to do it thooo
!original please
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
because someone seems to want you to solve a million dollar problem
IK
It just exists
I just noticed it's collatz oof
idk where to begain
doddy blud
Ideally hit the person who gave you the problem in the face
without more info, someone is trying to get you to solve collatz conjecture,
In which case you should throw the problem in their face and walk away
Since a mod is already here
@winter patrol does this count as automod bypassing
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Don't make those comments or troll
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Hey y'all! I have been tasked to examine the relations of the mean value theorem for integrals and differentials - I do not have a teacher for this and have some struggle with the lack of structure and clarity for my assignment so bear with me please - and I have gotten to a point where I would love to give a mathematical definition / proof for why a function would need to be continuous and differential within and around the intervel respectively for the MVT to apply. It is immediately obvious with a visual, but I lack the mathematical language / skill to describe this off the cuff and I have a hard time finding any sources on it directly, making it a hassle atm!
Picture for reference, how do I explain this with math rather than "look at it" (maybe it would become easier with a different discontinuous function?)
Try to come up with an intermediate value or mean value for the Signum function on [-2, 1]
"riemann is typing" is so funny to me in context. Hi! I do not know what a Signum function means, I study in danish, I could look it up real quick?
I will move on with this and consider it closed for now, it seems there are sources related exactly to my question available when searching related to this - thank you so much!
.close
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i need help
!help
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can someone solve it with desmos?
why desmos
cuz im shit at math
solve it with your brain
what does the quadratic formula tell you?
thats what the problem tells you
no, that's what the problem statement tells you
greatest value of ac
do you know the quadratic formula
ax^2+bx+c
thats a quadratic polynomial
yh
what is the quadratic formula
x=-b-βb^2-4ac/2a
use some brackets
do ts have tricks?
or screenshot if necessary
ik this
.
so what has to be true in order to have real solutions?
no
can u solve and send me photo
no
