#help-23
1 messages · Page 407 of 1
ohhh, so were looking for the upper bound
If you had now a sine term, good luck solving for x
and then isolate the upper bound only
you isolate x in 1/(2x²)<eps
my last line is wrong why?
You are not defining M to be x that's silly
The whole idea is M such that x > M
and M is that lower bound you just derived
in other words, you made a wrong assignment of variables
there is no upper bound then
since the funct is cont
which func is constant
g(x)?
g(x) is not constant, it depends on x here obv
g(x)=1/(2x²) was an upper bound for |f(x)-L|
and M(eps) is a lower bound for x
but we used the upper bound to find for the lower bound?
yes
no
we are only interested in upper bounds
for |f(x)-L|
the whole idea is to show that |f(x)-L| becomes small enough, you can like zoom in and there will be still points inside that little window
working with a lower bound of |f(x)-L| doesn't yield anything useful, cause you cant control how small |f(x)-L| would get
so was that the answer
just solving for M was our goal
I think my prof wants to prove it
That was scratch work
yeah
the good thing is the scratch work already tells you how to start now
Only M
epsilon is something arbitrary
imagine it's something given from the outside and your M(eps) has to work with that eps everytime
so were not getting the value of epsilon
that's what your proof is about
once we prove it
once you prove it, you are saying, give me any eps>0, my M(eps) will handle it always
so once we prove it, we can see if it works by plugging in epsilon which will give the corresponding M
you can do that yea
that's why we prove things in the first place
it guarantees results
<x?
yes
isn’t it x>M
Oh it’s the same thing
yes
blud
that is given
If x>M then ... is what you prove
You did the scratch work to find a suitable M
you're not interested in the case where x < M anyway, if I may add.
cause that's thankfully never the case with our M 
You are skipping steps
If a new reader looks at this they will be like "how?" "what just happened?"
Let eps>0 was good adding that, introducing variables that you intend to use, so the reader isn't confused
From the def. is fine
Then you write a small sentence like choose M = bla such that x > bla
then you start with |f(x)-L| and show every step until you arrive at < eps
using x > bla
do you think a template for this kind of proof would help?
maybe but i wouldn't do that
alright, sorry for interrupting.
all g
I think the philosophy of letting someone fail and thus gain understanding is of more of value than handing them blindly a template to follow
that is a fair point, sorry for not considering that.
Cause a machine can also just follow blindly orders but it cannot analytically think and that is the actual skill you acquire doings math
I agree. sorry once again; I'll step back.
It's okay lol no need to be sorry, OP seems to be gone anyway
just an exchange of ideas 
@hoary seal Has your question been resolved?
Oh I’m back
Let epsilon>0 and Choose M = some number > 0 such that |f(x)-L|<epsilon,
Then solve for epsilon once u sub values in
sin(x)/2(sqrt(1/2*epsilon)^2| < epsilon
wait wait, so you're presumably using the Euro sign as epsilon, but then in your expression you have the word epsilon in it.
so is the Euro sign meant to be epsilon or some other variable?
what the blud
Epsilon
then what does the word epsilon itself mean in your expression in the last line?
Let €>0 and Choose M = some number > 0 such that |f(x)-L|<€,
such that is wrong, that's what you want to show
Edited
You choose M such that x>M cause this is what you will be using in your proof
Yes choosing a value greater than x
But we don’t know the value of M , it’s a general function
Then solve for epsilon once u sub values in
sin(x)/2(sqrt(1/2*epsilon)^2| < epsilon
That's also terribly stated
You can't just plug in stuff, it's an inequality, not equation
This is how you structure the proof, and in the middle of inequalities you have to apply x>M
Oh then we can plug in the function, limit and make it less than epsilon
Which we already have from our scratch
|Sinx/2x^2| < epsilon
But u gotta also plug in M into x
To solve for epsilon
Two things: you dont write < epsilon out of nowhere, you derive that result
Second thing, you dont plug in M for x, you bound your expression using x>M, thus you inject epsilon automatically into the inequality and the math sorts itself out
Two confusions:
- how do we derive the result
- Bound your expressions using x>M? wdym?
- Algebra (look at your scratch work on how you started out)
- I can answer that only if you did 1. because only then you will follow up with the why
After you start with |f(x)-L| this is how you continue
If you are at this step we may continue
ok but here is the think how are |f(x)-L| and |sin(x)/(2x²)| related
just two expressions and you didnt derive them in your proof
of course it is
else it's just a claim
a proof is just a chain of logical arguments that follow up
do we need to show the working out from our scratch
here is the thing, you dont need to show how you got M
but in your actual proof, again you want to show |f(x)-L| < eps
so you start with |f(x)-L|
and from the scratch work you can see how to simplify this expression in the first place
so that we can apply x>M(eps)
and then your prove ends hopefully at < eps
îf you are stuck we can also do it together
in latex
so i would need to define whats f(x) and L
yes so do we write tht in our proof
basically these are all the steps
i also realized the =< were technically unnecessary but anyway
why coudnt have we done the scratchh work in our proof because were doing the same steps
because the scratch work is not a proper proof, you are working backwards
it would be circular since you assume what you want to prove in the first place is true
is proving when u need to go from finished product to the start product
it's only for you to discover a possible M
no other way
but sometimes when we dont know how to start, we do backwards thinking in hopes of gaining something that might help
I see
If you write these steps with = after you started with |f(x)-L|
here
then this is where things get interesting for the proof, but before that i want you to be ready
the "which simplifies" step is cocky, it's not trivial, in the exam you should really do the extra step with 1/2=x²/(2x²) but yes good so far, dont forget the =
do I find the upper bound now
how can you bound |sin(x)|
I mean the same proccess from the scratch work
bound sinx by 1 and -1
1
yes
the chain of logical steps
but now comes the part that separates your scratch work from the real proof
from 1/x^2 we need to derive that it is smaller than eps
fortunately we have our assumption
so we know something about x and how to continue bounding it (thanks to our scratch work)
do we make thhis an equal sign
we dont
from the previous step
cause |sin(x)| is not always equal to 1
from the previous step it's immediate
x^2 cancels and we have |sin(x)| left and for the denom we can omit the abs values cause x^2 is always positive
read the msg
|sin(x)| is bounded from above by 1
at some point you cant forget that
but when u say |sin(x)| < 1
isnt that same as -1 < |sin(x)| < 1
what
i mean
that's true but you dont need the lower bound
our focus is going up not down
at some point you have to remember the ultimate goal of what you're trying to do with these steps.
this is why Tairi at one point told you to write what you're given and what you are asked to do.
you cannot keep losing sight of the goal like this, OP.
thanks Hanako Yukari
?
I would have thought Hanako would not be this cordial with this OP...
but either way, sorry for interrupting; please proceed.
oh you know tairi
that's not the point
we dont care at all about lower bounds right now
can u show me like a demo
right now we are climbing up a mountain, so your focus is upwards not looking down
what sample what?
with another question
im asking bc from the start of proof, my understanding is not there yet
ok but then say that sooner not in the middle of something, especially that has been repeated for like 4 times now
that does not matter, in this case it's helping figure out the limit from the fundamentalz since it is squeeze theorem, we know that |sinx| is always non-negative AND is either less than or equal to 1/2x^2, as it approaches infinity, 1/2x^2 becomes zero, so logically, what's next
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Hi
a chord is just a line containing at least two points of your shape
I would've called it a secant line
in this case the points (x,f(x)) and (x+h, f(x+h))
it's like how chord is used in the context of circles also
Ook
So average gradient across that stretch
Hu
Its gradient at any point as well
But this too?
"average gradient across a stretch" sounds like you are taking a bunch of points between two boundaries and averaging the gradient. It is simply just the gradient line between two points
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Did they forget a ... in that sum?
Yess
Because if so, I think rationalising the denominator of each term could go pretty hard
Yess this is the general term but what can i do next
Each term is $a_k = \frac{1}{\sqrt{4k-3} + \sqrt{4k-1}} $
I tried telescoping series
do what kaynex said
yes thats the idea
But terms are not cancelling
!show
Show your work, and if possible, explain where you are stuck.
u don't need exact answer for this problem
u just need to know what it's around
ok cool
,rotate
so it's going to be something like
1/2 * (sqrt(n + 2) - sqrt(n))
It's almost telescoping. It's like you're missing half the terms you need
Yess
Is it multiple choice?
But how can i do it
Nope
Single answer out of the four options?
Yess
that's multiple choice
Oh ya sorry i mistkanely thought he is saying about multiple correct
So single answer?
Yesssss
Then S > 24 cannot be the answer, because then S > 18 would also have to be true.
S < 24 cannot be the answer, because one of S > 18 and S < 18 must also be true.
Now we just decide between C and D.
If B is correct, C must also be correct.
Do you know how to solve this
Yesss you are absolutely right
Perhaps we have the choose the tighest inequality.
How can i do that??
i mean that's what the context suggests
Anyway, is it intended to be done using calculus?
No idea i have not tried that thing
Do you know calculus?
A little bit
But if i do with it i will be having (4n-1)^3/2 with the limit from 2500 to 1 with 4n-1 also with same thing
It will be so much bad
Thia question should have a other easy way
@cunning pasture any idea bro how to approach this question?
<@&286206848099549185>
hi
Hi Prof.
after a bit of work
i come to
$$
S = \sum_{i = 1}^{4999} \frac{\sqrt{2i-1}}{\sqrt{2i+1}} - 4999
$$
fluX
oh wait im wrong
How did you do this? @compact flame
.
hm.. this would yield something
try doing smth with the "missing series"
like 1/sqrt(3) + sqrt(5) + 1 /sqrt(7) + sqrt(9)
maybe a combined analysis of this with the series above yields a solution
note that they sum to form this expression
Maybe this sum can be compared to a telescoping series which is smaller than this sum.
Because root(10000)/4 = 25
And WA gives its value > 25.
a very loose bound would be due to concavity of square root function the sum of this series is less than the original.
if you add them your sum becomes telescoping
this sum will be less than twice the original sum
Maybe use that 1/root(x) > 2(root(x) - root(x-1)).
@shrewd frost Has your question been resolved?
Can you give me a little bit idea how will i do that
Gimme a small example please
I am getting confused
Ok, I know a solution (searched).
By the last inequality,
1/(4root(x)) > (root(x) - root(x-1))/2
|| 1/(2root(4x)) > (root(x) - root(x-1))/2||
||Take x = m + 1||
1/(2root(4m + 4) > (root(x) - root(x-1))/2
|| 1/(2root(4m+3)) > 1/(2root(4m+4) > (root(x) - root(x-1))/2 ||
So 1/(root(4m+3) + root(4m+3)) > (root(x) - root(x-1))/2
||1/(root(4m+1) + root(4m+3)) > 1/(root(4m+3) + root(4m+3)) > (root(x) - root(x-1))/2||
1/(root(4m+1) + root(4m+3)) > (root(x) - root(x-1))/2
||Now take the sum of both the expressions from m = 0 to m = 2499 or x = 1 to x = 2500||
||We get S > 1/2((root(1) - root(0) + root(2) - root(1) + root(3) - root(2) + ...... + root(2500) - root(2499)) = 1/2(root(2500) - root(0) = 1/2(50) = 25||
So S > 25
denote your sequence with A
general term of A $a_{k} =\frac 1 {\sqrt {4k -1}+ \sqrt{4k -3}} = \sqrt{4k-1} - \sqrt{4k -3}$
now define a new sequence for the missing terms \
$b_{k} = \frac1 {\sqrt{4k-1} + \sqrt{4k+1}} =\frac{\sqrt{4k+1} - \sqrt{4k-1}}2$
now compare kth terms of both you will find $a_{k}> b_{k}$
professor paradox
@shrewd frost Has your question been resolved?
Thank you so muchh @near sky @cunning pasture
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to guess a random number and being told higher or lower each turn the number is from 1-10000, whats the expected number of guesses to end game at picking randomly but still following higher lower criteria
the best strategy is binary search
Yeah but they said random picking
oh ok
Whilst still following if they are being told its higher
So theyll pick a higher random number
can you reword it?
cuz isn’t the answer just halving the higher/lower etc
like can i give an example
sure
say i choose say 2000
so you say 1354(random gueess from range 1-10000)
I say higher
You go 9456(random higher guess)
I say lower
You go 2679(random guess but it lies between 1354-9456)
Like this
How many turns is it expected before you get to the number
well i can be (n-1) since it’s random
for example
take i say the number 10,000
then you guess 1
then 2
then 3
….
9,999
10,000
Thats not random tho
it may depend on what the number is. like a number at an extreme can probably be guessed in a random no. of guesses faster than a number around the middle
I mean that can happen but very unrealistically
well it may look like it isn’t random
i’m just saying like
n-1
Yeah thats what, its like very hard cuz u have to account a general case for every pick too i feel like
try with a smaller number
1-5
oh wait it is just N guesses
that’s the most probable
I mean in N guesses youre sure to get it
It says expected
Like as in most probable number of guesses
yes
why not start simple, say the number is 10k. so E_10k = 1/n (1+E_0) + 1/n(1+E_1) + 1/n(1+E_2) +.... 1/n(1+E_n-1) when E_k is the expected number of guesses to get the last number for k many numbers.
please excuse me if im wrong
Wait ur cooking
this should be the case that E_n = 1 + 1/n + 1/(n(n-1)) + 1/(n(n-1)(n-2)) + ... + 1/n!
maybe not
It looks like linear search
Like ur picking one and throwing it away
Each miss eliminates a lot of numbers each turn
wait that formula isnt correct
interestingly
E_n = H_n
where H_n is the harmonic sum
so with that I wouldnt expect anything much better for non nice values of the correct number
Isnt linear the worst
i mean in terms of a nice formula
I mean yeah that formula is pretty funny
I mean why do i even have to do ts in cs
Ts pmo gng
Oh damn theres a formula for this
Yeah it definitelt looked like so
wait it doesnt depend on the correct number?
or is it averaged over all designated correct numbers
Apparently it doesnt
Its the overall expected value when youre also picking a random number
From the interval
alr thats cool
now prove it lol
you have some high level cs for pre uni
its very cool
oh sorry for the smurf 😄
damn
I got into uni 2 years ago i should change it
or just keep it ;)
Haha true that
@mossy ridge Has your question been resolved?
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Hi, I have an exam tomorrow but I needed help with a question on the continued proportion lesson
What happened in the third step here? What property exactly was used and how did it change it to that?
what exactly is the third step
this?
do you have a table of properties of proportion in your book
I do but this one was never mentioned
The ones I have:
Interchanging the means
Interchanging the extremes
Addition and subtraction of anticedents and consequents
Inverse of the proportion
Cross multiplication and its inverse
show the formulas for all of them
yea property 3
The application? (K)
But it wasn't even used.
There's no k
yea it was here
Huh?
Yes it says find x and y
I understand until they were x over y = y over 4
But how did it turn to x + y over y + 4 = y over 4?
.
Oh, but where did the y over 4 come from?
if A = B and A = C then B = C
i'll use capital letters to distuinguish from property 3
I don't get it...
which one
this?
or this?
Yeah this
I still don't understand where did the 4 over y come from
We replaced the k with it?
there is no 4 over y
in this step
I mean y over 4 sorry
did you learn this property
No
i suggest reading and learning it then. it's a very basic algebra fact https://www.cuemath.com/numbers/transitive-property/
maybe your book calls transative something else
But what does it have to do with that?
they use transitivity here
and property 3
Ok
this is all you need to read to understand
this statement
OH WAIT
"= one of ratios"
y over 4 is a ratio so we replaced k with it?
It's because the sum of the anticedents over the sum of consequents would equal one of ratios and y over 4 is already one of the ratios
?
yes that's what "are in proportion" means
Oh I get it now
I feel so dumb lol 😭💔
Thank you for helping me tho
"y over 4 is a ratio" is pretty wrong tho
being in proportion has a very specific meaning you should remember. not just y over 4 is a fraction
Ok
"Important Note 2"
.close
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I mean technically this is undefined right
$Cov(X,a) &= E(Xa)-E(X)E(a) \ &= aE(X)-aE(X)\ &= 0$
astral
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
$Corr(X,a)=\frac{Cov(X,a)}{\sqrt{(VarX)(Var,a)}} = 0$
astral
sm1 help with my statistics
yeah I suppose that's why they're uncorrelated in a somewhat pedantic sense
I mean certainly they can't be correlated (because the correlation coefficient is not defined) so therefore one could say they're uncorrelated
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Can any1 draw components in here as i cant figure it out
start with the 6 N one, it'll be like 6 sin alpha north and 6 cos alpha to the right
the 5N one is similar, use the fact that it's alphaº from south (or 90º - alphaº from the right)
@solar inlet Has your question been resolved?
Tysmm
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guys whats an easy way to figure out what the range of an function is?
for example 2x^(2) + 3x + 1
i know theres an way with the vertex form
for a quadratic you can find the vertex and direction of the parabola
Servus
is the direction upward open for my example because it is 2x^2 and not -2x^2?
yo
nvm
how do i convert it to the vertex form, i am stuck idk what now
yes
complete the square!
wym by that
completing the square is how you derive the quadratic formula
have you seen the quadratic formula before?
i'd say go google or look at your textbook for the completing the square section
do u mean this?
Brauchst du Help
yes i do
tf
that's the quadratic formula
bruh
is there no easier way to figure out the range
i dont wanna remember an weird formula
it's not a very weird formula
the vertex is perfect
the trick is to remember how to get to the formula, not the formula directly (although many people are able to remember the formula because it is used often)
for range
the thing is that its just not worth it to remember just for the range
frosst knows their stuff
thats like 0.1% of the examen
where is it used to?
if you're only trying to pass the exam you've got the wrong attitude to learning :/
i mean i wanna get an good grade
if one wanted to know the roots of a quadratic the formula will give it directly
there are many occasions when one wants to know this
if you study calculus, in integration you will again meet completing the square again
quadratics is quite the backbone to a lot of maths, it will show up all the time
😔
you can do that procedure to ax^2 + bx + c = 0
and then you will find that x = your formula
<@&268886789983436800>
okay ill try
if you get confused you can google this there are plenty of material online on this topic (completing the square)
okay ill check
Tim do you also need to study differentiation for the exam
ableiten?
yes
Because you can also use this method to find the vertex (even though it is overkill)
i always used the pq formula
is that factorising?
idk
The pq formula is for the roots, but I guess you can also use the roots to deduce the vertex
do you get something like a(x-b)(x-c)
so to be honest there is another way
for extrema i jsut do f'
well that also works actually
i didn't know if you'd studied calculus yet because typically quadratics is taught long before calculus is introduced
there's also the method of using the axis of symmetry
ye i maybe had it once but didnt needed it till yet
This quadratic stuff is taught in middle school usually
then you can plug in the point to know where the vertex is
yeah i learned about this in grade 8
is this the vertex form of the example?
<@&268886789983436800>
<@&268886789983436800>
do u know why its only b/2 where i marked it?
shouldnt it be bx/2
they've split it up
you see how in the left it's got a b * x rectangle
they cut that rectangle vertically into 2 pieces
1 of the halves got put horizontally under the square
how did they go from the top to the bottom?
how the hell did they simplified that
Try expanding the bottom
ye okay that makes sense but how did they do that
They look at it and go oh I can factorise this
(Notice that they’ve constructed this part specifically so that they can factorise it)
no
if you have (x+a)^2 it's always x^2 + 2a + a^2
yes
wait i jsut realized
can i just cut the middle from x^2 + 2a + a^2 and take the x and a and square them?
does that makes sense?
ye i think i got it
but what do i do if i got functions like these
The first two are just with a=0
3x+1 what is that graphically
and what would be e ?
okay i didnt thought abt taht one, thats just infinity
in the first one there is nothin so naturally?
-# also dont you recall x²?
wdym by infinity
the range of y is R
okay i think im stupid
i thought to comlicated, if i try to imagine the functions in an coordiante system then this isnt hard
x^2 is the range of y, R > 0 ?
how do i say that
can y=0 be attained
whats attained
angenommen werden
hä
Do you know what range means in the first place for a function
what value y can be?
yes
for what value?
x = 0
for example, if you denote W as Wertebereich
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yo this question i s regarding critical points on a 3D multi variable surface,
i need help understanding the intuition right when solving the system of equations, i just dont understand the correlation exactly here
like when i took the partial derivatives, i got infinite tangent lines going in the x direction, and infinite tangent lines going in the y direction
but how does that exactly turn into two lines intersect where the intersection is their solution
(im assuming thats whats going on there)
also how do you tell if this a local minimum or maximum or an absolute minimum / maximum without graphing
Can you clarify what you mean by infinite tangent lines?
In general one uses the determinant of the Hessian matrix as an analog of the second derivative test for 1-variable functions to classify the critical points locally.
To determine if it’s absolute you need to study the function in more detail there’s isn’t a particular all-encompassing method. (At least not for a domain which isn’t compact)
okay so
say you have an infinite differentiable 3D surface
and you take its partial derivative with respect to x
what this means is that for points in that space, y stays static and x changes
so for every point (x,y,g(x,y)), youre calculating the instantanious rate of change going from (x,y,g(x,y)) to (x+h, y, (fx+h, y))
ya know
so thats just gonna be a set of infinite parallel tangent lines pointing towards the x direction
and vise versa
At every point you get one line which is tangent to the surface with direction $\begin{bmatrix} 1 \ 0 \ f_x(x,y)\end{bmatrix}$ and one line with direction $\begin{bmatrix} 0\ 1 \ f_y(x,y)\end{bmatrix}$.
I wouldn't really think of them as infinitely many tangent lines in the x direction and infinitely many many tangent lines in the y direction though.
Azyrashacorki
@honest idol Has your question been resolved?
The goal for critical points is that if you have an extremum somewhere at a point (x,y,f(x,y)), it ought to be the case that those two lines are just horizontal, i.e. they lie in some plane z=constant, i.e. the partials are both 0.
This amounts to solving the system of equations $$\begin{cases} f_x(x,y) = 0\ f_y(x,y) = 0\end{cases}$$.\
In this specific case you showed above, those equations are linear. Generally they may not be, you just need both partials to be 0 simultaneously at that point.
Azyrashacorki
but before this though im having trouble understanding how those tangent lines in the direction of [0 1 f(x,y)]^T and [1 0 f(x,y)]^T correlate to the system of equations
Well we set the last coordinates to 0 so that the z-direction is 0, so that those tangent lines lie in a plane z=constant.
im tryna visualize it
There's lots of ways to interpret this.
It's the same as requiring that the tangent plane at that point be horizontal (like parallel to z=0).
so like, when you take a derivaitve and set it = 0 youre looking at when its horizontal
so that is at least 1 tangent line if a critical point exists
Both of the partials need to be 0 for the plane to be horizontal.
why would you think of a plane?
i mean its just two orthogonal tangent lines
right
They're not necessarily orthogonal, but they will be linearly independent, which means they identify a plane, which is the tangent plane.
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You could also interpret it without talking about tangent lines at all.
If f attains some extremum at a point, then it should be at a point where it doesn't change in neither the x or y direction (just like a 1-variable differentiable function has derivative 0 where it has a supremum)
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Hello, dumb question, but what is the value of k here?
Hello there
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✅ Original question: #help-23 message
hello
Right so for average rate of change,
You can simply apply change in R / change in T
nonono i get how toget the average rate of change and the inst
im asking for the value of k, cause the problem states that k is a constant
(f(a) - f(b)) / (a - b)
you cant comment on value of k sadly
so just.. retain k as is
Yeah
searching up the law gives k as a constant of 5.67*10^(-8)
But idts hes doing it from ohysics point of view
yeah
so what do i do? ill answer it with variable k? no need to sub k with the actual value?
K isnt a variable and since your a math student, yeah it wouldbe fine to let k as it is
Unless the value of it has been mentioned to you
right
i would write the answer in terms of k if you don't know it like what yajant mentioned
just like answering in terms of pi or something
right
so basically this

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A two-compartment, closed container holds a mixture of 50% distilled water and 50% neutral vegetable oil. The mixture is left undisturbed in the laboratory for several days. During this time, the vegetable oil increasingly settles in the upper part of the container. This process occurs at a decreasing rate; that is, initially a large amount of oil settles in the upper part of the container per unit of time, but over time this process slows down. At the end of the observation period, all the oil has settled in the upper part of the container, and all the distilled water in the lower part. The following diagram represents the container, serves to facilitate understanding, and acts as a legend for the possible solutions.
!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
What snapshots can be observed at the beginning of the period, at exactly
half the time, and at the end of the period?
I basically need to choose bwtween these options
The option that describes the liquids in the container
So im thinking
It has to be C or E
yes
Becuase. B is in the wrong direction
A is linear
So its bad
And d is bad
And i was thibking
That
It should be E
Becuase
It says that the vegetable oil rises up
At first fast, then slower and slower
And C is basically the opposite because it rises faster and faster
This is my thought process
Am i wrong?
I feel like a mirror image of c would make the most sense
yeah
Thats why i said a mirror image
Becuase more and more vegetable oil is at the top
Like, if you interchanged the position of the oil and water, then c would make sense
As it is, neither of the two make a lot of sense to me
Yeah but the others are striaght up wrong
Id probably go with e, and then challenge this question afterwards
So it has to be between C and E
The question can be incorrect
E is the most appropriate answer of the given options
I believe the question is incorrect
It makes no sense
I think they interchanged the position of oil and water in the middle observation
How is the process slowing down if the curve from C is increasing!
It makes sense if you take water on the right, and oil on the left
Water is down and oil is up
Yes
And im saying
If it says that the slope of the curve should be decreasing over time( cuz there is less and less oil going up over time)
Then how can it be C if the curve of C has a slope that is increading over time!
Increasing
Im saying that C is the correct option, but if and only if The water is on the right, and the oil is on the left, ie, a mirror image
The slope will then be decresing
As it is, neither of the 5 options are correct, unless the examiner decided to troll you and view the vessel from behind as opposed to the front
I dont understand why you think its mirrored
The starting position is 50% 50%
Then
The curve that is above
In the upper half of the container
Goes towards 100% oil, so to the right
And the one in the bottom half goes towards 100% water , so to the left
Look here
For the top half 100% is on the right side and for the bottom half the 100% is on the left side
So it's correct
The oil goes towards the right and the water towards the left
Well then, can you explain to me why there is more water in the upper portion in option E, when water is supposed to occupy the lower portion?
Ugh this is frustrating
So my idea was that there are 2 graphs in here
Separated by the middle line
The curve in the upper half describes the percentage of oil in the upper half
And the curve in the lower half describes the percentage of water in the lower half
At first they are both at 50%
So a straight line through the middle
Then the curve describing the oil, so the curve in the upper half goes towards the right
And the one on the bottom goes towards the left
Becuase the oil and water reach 100% over time respectively
So this is exactly what we would have in E
So in my view there is no curvw that shows water in the top half
Only in the bottom half
So i guess we are viewing the problem in 2 fundamentally different ways
We are viewing a problem with no correct solutions imo
Well usually these questions are solevd by eliminating the even worse options
Until the least worst remains
The curvature on E isnt correct
The curvature on C is correct, but they mirrored the graph
This is what it should look like
Yes precisely
E is the most appropriate answer, but it isnt the correct answer
Yet the book says its C
If this is something that showed up in once of your cram school/coachings tests, you can talk to your mentor about this question
Thats what we would do. And either the question would be cancelled, or it would be stated that they observed it from behind
Either they mean that it can be observed from viewing the container from the behind, in which case C is correct
Or the question is erroneous
Not all questions are correct yaknow
Brother the question in itself is wrong
Unless its from a test or something, just strike it out
Because E will not get you any marks if this is a option present
But this makes no sense
How so?
At the end the oil has to be at 100%
So how would your end look like
E
Hm so in the bottom half, your curve is heading towards the rightmost value
And you re saying that in the end, it will reach the leftmost value
?
Here, bottom part is mostly water, and upper part is mostly oil
Ok so what does your graph represent
Whats the x axis and the y axis
Honestly, all i meant is that this will be the intermediate curvaturw
Yeah but you gotta respect the x and y axis
They tell you that the x axis is the % of oil and of water
So you know that in the end you will get the end of E
I already told you, the book messed that up
The curvature on E is incorrect
Why
Do you understnad that there are 2 separate graphs?
Maybe it helps
If you cover the bottom part of the contained with your hand
So you just see the top half
Which represents
The oil
Which
- how is there more water above the x axis, and less water below the axis?
Has to go towards 100%
Ok lets look at E
It starts with
50% water and 50% oil
Yes
Now lets look at oil only
From the intitial 50%
In the top half of the container
It rises
Towards 100%
Towards the rightmost corner
Hang on a second
THATS WHAT THISE GRAPHS MEANT
I thought the Area was what we were looking at 😭
Thats totally on me
But then, why wont it be c?
🤣🤣🤣🤣🤣🤣
Because as i said
It says in the question
That
The oil is rising
But it rises slower and slower
So i was thinking
That this mens
Means
That the slope of the curve keeps decreasing
Yeah fair enough
At first the slope is big then it slowly oges towards 0
So then i look at C
And I see that
The slope keeps increasing
I think i see the mistake
It doesnt decrease
Look at the graph for the water portion, the slope is decreasing in c, and increasing in e
The slope for the graph of oil in c looks like its increasing, but its actually decreasing
The reference axis for the oil portion is the top right, not the bottom left
If you get what i mean
Yeah
How
Its concave downwards
The top part cannot be judged by taking the bottom left as the reference
The reference for the top part is top right
Yeah lets ignore the bottom half
Then youll need to take the top right as the origin
🫂
Ok
Lets just look at the top part
Just pretend that the bottom part doesnt exist
So the oil
Why
We look at.
Why do you want yo make this harder for yourself
If youre going to look at the top part
Oil goes from left to right, 0% to 100%
Then flip your phone around and look at thebottom part, thats whatll be more accurate
We can take the line separating the compartments as the x axis
where x is the % of oil in the top part
Thats the fallacy
The midpoint is not the origin
This int a standard cartesian plane
I like your name
Just prwtend it is
The this line to be the x axis
Wait
No
Omg
🤮🤮🤮🤮🤮🤮🤮🤮🤮🤮
Real
This is what i would do to that container
heyyy
Sup
Which one
How u guys doin
So, like, did we come to a conclusion?
We are trying to understand this problem
what are u guys discussing bout?
send...
Its above
ok lemme see
Check the pinned message
.
Um
So anyways
How tf do we get a curve
If
Ah shit fluids
The middle photo
Is supposed to be
A single instant
From the midway of the process
Youre misinterpreting the curve
Its not a function
Its not
Then wtf is it
Just read the whole problem, you re only supposed to choose between some pictures
The vertical distance from the base is literally the point in the vessel
And the horizontal distance is like the mole fration curve in liquid solutions
The more you go to the left, the more water
The more you go to the right, the more oil
You get my point?
Yes, but oil is only described in the top part
And water in the bottom
I think
And look
If you look at the container from sideways
,rccw
Nooo 😭
Initially its a homogenous emulsion of oil and water
Then it starts seperating out
I think its like this