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hm so either B = F and D = f, or B = f and D = f'
yeah
and we've established above that C is the derivative of D
so
B , D, C
i mean this has to be it
well C is the derivative of D (im not gonna fact check that), and D is the derivative of B, so...............
(mb)
im a bit confused here so if i were you i'd wait for another helper but i feel b,d,c is correct
which is only true for D
but D has a positive slope
so A should have been in the positive quadrant
yes
yeah also this is an easy question the only reason i am bringing this up is because someone got a different answer than me
D has a positivr slope till 1-2 or at 2 then it decresed
how?
no
C decreased till 3 then increased toward x=infinity
I agree
or B A and C
it's not exactly clear on the image if A and C cross the x axis
@thick oracle Has your question been resolved?
<@&268886789983436800> spam
That's very kind of you 
๐
Lmfao 
@thick oracle Has your question been resolved?
if F = B
f=C
f' = D
since B cant be anyone's derivative cuz B is 0 at 0 and noone's slope is 0 at 0
B is either F or unrelated
if its unrelated, the only possible way we can arrange them is
ACD or DCA
left to right in the order F,f,f'
none of them make sense cuz A and C are negatives of each other, if A is f(x) then C is -f(x)
the only option left is BCD
The diagrams show the graph of a function f, its derivative f', an antiderivative F of f and another fourth graph. Assign a graph to each of the functions f, f' and F and explain your reasoning.
Not really in a mood to assist, sorry, but I thought a translation might better help other helpers here
ok no this is correct symply because D crosses the x axis at 1 (min of B) and A crosses at 2
you can close dw
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!nosols, I believe?
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.
mb, instinct
this is a definite integral
think for a minute then tell me
is it 0
why do you think it's 0?
i added one to the power
so its 0*x^1
and thats all timesed by 1
so 0 times anything is 0
can you answer this now?
yes its 0
there we go
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Ik this is the answer but is there a way to be more accurate? I remember using a way but I forgot it
please @ me
more accurate in what sense?
@toxic harbor
in drawing it
plot some points using the transformed function.
oh uh no not really
unless u use desmos and copy it exactly
pick some values of x and compute the corresponding values of y.
then join them in the expected shape.
what is compute
calculate.
so lets say i used 2 i got 8 where does y go?
the transformed function.
also, if you used x = 2, then y = x^3 = 2^3 = 8, so x = 2 leads to y = 8 in the original function.
ohh now i see where my mistake is lmao
but you want the transformed function, so.
but also, note that the question asked you to sketch the transformed function.
when a sketch is involved you have some leeway anyway.
whats leeway
a sketch by definition need not be perfect.
but some words ive never heard of
if you are told to graph the transformed function then you should be more accurate, but you're not expected to be perfect anyway.
and the transformative one does it have to be the same size?
you're not compressing or stretching it, so...
i mean like in length
I know.
what if it was 1 box smaller
then it depends on whether your examiner is in a good mood.
โ
thank you
for your help Chiaki
it is very much appreciated
๐
have a great day
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Let triangle ABC be isosceles at B. The line BH is the angle bisector of angle B.
Let K and M be the feet of the perpendiculars drawn from H to BC and BA, respectively.
a) Prove that triangles BKH and BMH are congruent.
b) Prove that BH is perpendicular to CA. From that, prove that
BH < \frac{BC + BA}{2}.
c) Let E be a point on segment BH (with E \ne B, E \ne H, and E not on line KM).
Construct point I such that E is the midpoint of segment MI.
Prove that IK \parallel BH.
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
1
have you drawn a diagram?
รe
If you have, may I ask you to upload it?
Hold up
Here ya go
Currently on c problem
ive proven that bh is perpendicular to mk, now i have to do the same with ik
Hm I have a hint which may or may not work
In a right angled triangle, what are the properties of the median to the hypotenuse?
observe in right angled MKI
that ME = EI
so EK is a median
since its to the hypotenuse, do you know the propety that EK = ME = EI?
i feel if you could somehow show ME = EK, you're done
@vale orchid is this clear? this may not work, take my words with a pinch of salt
Well try atleast.
then you can show by the properties of isosclees triangle(angles opp. equal sides are equal) and angle sum property(angles sum to 180) that it IS a right triangle
I can clearly see two triangles, if you show congruence between them, then its done. hint: you'll have to use the fact that BMH congruent to BKH
yea the 2 small triangles on the top right
I mean, maybe, but what i as thiking of was MHE and KHE
do those triangles have anything to do with the angle that were focusing on
those triangles will show you ME = EK
as I've explained before, since ME = EI, you'll have ME = EK = IE, and from there you can deduce MKI is right angled at K
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this is gonna sound idiotic of me but (this is my teachers digital writing)
is that a "-2" or "- 2" for question 1
minus two
im assuming the 3 is also "-3" and not "- 3" in question 1
negative three times (x minus two)
the kerning is shitty but generally you assume its a minus unless its completely obvious
does this answer your question?
yes
ok cool
oh also
it appears that everything will be some combination of
- a number
- (x plus something)
- (x minus something)
- (something plus x)
- (something minus x)
(not all of those at once)
so if youre not sure just check which one its closest to
it's .close.
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Anyone?
!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
and is the point to just expand it
unfortunately no, i can help YOU try to solve it but i need effort from your end
What effort?
You've already sent it
have you tried attempting the question
Factorissation
Answer this, please. @serene jackal
1
?
How? Send a photo of your work so far, if you've written down something
where have you gotten this question from
From my book
is this schoolwork, where you've done other questions that are similar to this one
In copies...This is my first question so far
you've studied this at school, correct?
do you know how to multiply brackets in algebra
alright, so can you start with that and open the brackets
No! ....
ok
as i've tried to tell you before, no one here is going to just "solve" and give it to you
!nosols
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.
we can walk you through it if you want
!noans
The purpose of this server is to help you learn; please don't ask for direct answers. Ask for guidance, explanations, or feedback instead.
Ok
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how do I do this
my intuition is its not countably infinite
y?
I believe your intuition is correct 
cant see how there would be a bijection
hm, I don't want to give away too much, but a good idea might be to associate each subset of N to a sequence in S
that way, you construct an injection from P(N) to S, and since P(N) is uncountable, so is S
the real work comes from coming up with a sequence for A \subseteq N, but it shouldn't be too bad 
Whats P(N) here
the power set of N, which has cardinality |R|, i.e. uncountable
the power set of N is just the set of all subsets of N
how would I form an injection from S to power set of \mathbb{N}
^^
and you've got the injection the wrong way around
Yeah this is one of the few things I know ๐ญ
you want to inject P(N) into S, because that means S will have equal or greater cardinality than P(N)


my suggestion is to try fixing a subset A of N and coming up with a sequence q_A of S you can assign to it 
makes sense makes sense
that'll give you an injection automatically (via A \mapsto q_A)
but howww can I complete the set of S in that case
bc like its the set of ALL rational sequences
S is a subset of the set of rational sequences, not the rational sequences themselves 
I also don't quite understand what you mean by "completing" S 
oh wait yeah am being dumb
Idt I need to actually
if Im injecting P(N) to S it doesnt need to be surjective
a very classical example of a sequence in S is q_n = 1/n, and I suggest you think about using that sequence for this problem 
indeed, and we don't require a surjection
we aren't showing these two sets have the same cardinality
just that one has a cardinality equal to or greater than the other
I think I'm beginning to understand
an injection from the smaller set into the bigger one is sufficient
@steep pike @dusk widget consider a diagonal argument to prove its uncountable
not sure what this means sry
huh. is that necessary? 
see hlounge for my initial idea 
cantor provided a famous method of proving a certain set is uncountable. the same method can be adapted for our set
@dusk widget so with the power set of N
can my injection be
1/n * sample mean of power set
not power set but for each element in power set
bc its still rational and tends towards 0
err, I don't know anything about sample means, sorry 
I had a what I think is simpler idea 
just the mean
the method is to assume there exists an enumeration, ie a bijection N->S, then use the enumeration to construct an element of S that does not appear in the enumeration, giving a contradiction
that sounds like you're gonna be mapping many subsets to 0, since there are infinitely many infinite subsets of N 
is that not fine
that's not an injection
oh wait yeah
you're mapping a bajillion things to one :p
i have been directed here
a more natural idea would be to define a sequence that depends on the subset itself
like q_n = something for n in A, and q_n = smth else for n not in A
sry am new here ru doubt asker or solver?
asker
who solves it
higher
ohh
if it hasnt been suggested already, a diagonal argument similar to cantor's diagonalization argument to show R is uncountable is likely helpful
i did above
yeah idk how to do ts
i see, sorry then
the proof method is given here https://en.wikipedia.org/wiki/Cantor's_diagonal_argument#Uncountable_set
Cantor's diagonal argument (among various similar names) is a mathematical proof that there are infinite sets which cannot be put into one-to-one correspondence with the infinite set of natural numbers โ informally, that there are sets which in some sense contain more elements than there are positive integers. Such sets are now called uncount...
is A the power set here
I'm kinda unsure now because Roketto thinks the diagonalization argument is easier, and I don't want to confuse you by giving you another independent approach 
no, A is a subset of N, or an element of the power set
you're mapping elements of the power set to sequences of S
that is the injection I initially wanted
the core of Cantor's diagonal argument is:
- assume the reals (let's say in the interval (0, 1), for simplicity) are countable
- list all of them in decimal format (use zeros if the number terminates) out by enumerating them
- construct a real number in (0, 1) by choosing the diagonal digits of the sequence
- this real isn't in the list, which is a contradiction
note that in the link cantor is specifically proving uncountability of T=set of sequences of 0s and 1s, but the method can be adapted to our set S
I honestly might bow out of this channel for the time being, and let others give the diagonalization approach
you may also adapt this to any reals, but writing the real number in base 2 (binary)
I'll ping you elsewhere and explain my idea afterwards, perhaps 
try to see if you can adapt this to S:?
in this injection, would q_n just become every element of power set
wait I kinda remember this
q_n has to be a rational sequence lying in S, not a subset of N
yes I mean the set of q_n mb
great! I'll let Roketto and Atlantis take over then 
lemme ping you in a different channel later 
i am gone, i was just told to check this channel by someone 
so like remind me
is the argument that
ill repeat the method
the method is to assume there exists an enumeration, ie a bijection N->S, then use the enumeration to construct an element of S that does not appear in the enumeration, giving a contradiction
yes the diagonal forms an element that does not appear in the enumeration, giving a contradiction
okay okay got it
so applying this to the question
do I like assume countable and say S is the set of S_i for i in naturals
we assume countable ie there exists a bijection N->S (we call it enumeration)
then define new sequence S' st S'_j = S_i(j)
argue that this is none of the S_i s
?
I thought I had ๐
see the details of how s is constructed above
basically we make each diagonal entry different from its original value
this is the key to constructing a sequence outside the enumeration
but in this case how do I make the diagonal entries diff bc we're looking at the entire rationals
do I just to
like 1/ diagonal entry or smth
I cant guarantee that this is different in every case
remember our new sequence must be in S, ie rational entries and converges to 0
how do we change the diagonal entries to keep these properties?
square it maybe?
but we also need them to be different from the original values
doesnt work if some are 1s
yeah that was what I was thinking
can I do square then define differently for 1
what would you do for 1?
like 1/j for jth term maybe
ya
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yw!
@steep pike ah, here was my idea: fix a subset $A \subseteq \N$ and consider the sequence given by $q_{n, A} = \frac{1}{n}$ for $n \in A$ and $q_{n, A} = 0$ for $n \notin A$. each such sequence is clearly in $S$, and two subsets $A, B \subseteq \N$ generate the same sequence if and only if they are equal: $A = B$. then the map $\iota: P(\N) \to S$ given by $\iota(A) = q_{n, A}$ is an injection, hence $|P(N)| \leq |S|$, and we deduce that $S$ is uncountable.
higher!
I'm glad you managed to get the problem done via diagonalization though c:
this is rly clever
analysis enjoyers are next level
I am no analysis enjoyer, I fear 
you can find many instances of me hating the subject 
me too dw
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โ Original question: #help-10 message
@steep pike u need a different formula. for example if the diagonal is all 2s then the new entries dont converge to 0
can I construct diagonal st if entry greater than 1, take reciprocal, if not leave as is?
if 1, = 0
I feel like this still doesnt guarantee convergence
what if diagonal is all 1/2?
yeahhh tricky
hmm
i^i if less than 1, i^-i if more than 1?
def converges to 0
and still rational
@upbeat plinth
@steep pike Has your question been resolved?
its bad if diagonal is all <1..
what do I do thennn
so far u tried conditions based on 1. try a simpler condition
we want convergence to 0 so try conditions based on 0
yeah idkkk
so try .. if entry is 0, .. if entry is not 0
if entry is 0 then 0
if not then..
0?
hows that unique tho
gen losing my mind over this question
u forgot every entry needs to be different from original value..
I didn't I js dont know how to guarantee this or find a diagonal such that this is true ๐ญ
recall the conditions we need on diagonal sequence:
- rational entries
- converges to 0
- every entry is different from original value
yeah I got this I js rly cant find anything that doesnt contradict at least one of these
our conditions are if entry is 0 or not 0
whats the simplest nonzero sequence converging to 0?
1/n
so entry 0 leave as is
entry non zero choose 1/n
unless 1/n is already on diagonal
else 0?
??
will this work
thats why I said unless already on diagonal
lets try again slowly
the conditions are if entry is 0 or not 0
if entry is 0 what do i pick?
if entry is not 0 what do i pick?
i being a natural not the entry
1/entry unless entry is 1
if 1 then 0
no try simpler
just 0
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yw :))
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Why is the b not distributed but the 2 is
because the b is being added to the whole 2(b + 2b) term.
multiplication precedes addition, so the distribution (being a form of multiplication) is done prior to b being added to that product.
if it was (b + 2)(b + 2b) on the other hand, then the b will have to be distributed as well.
well because the b isnt multiplied with (b+2b)
becuse its 2( something + something)
when u have 2( x + y) for example
it means that its 2(x) +2(y)
so many helpers all of a sudden. I'll step back then.
a sorry- 
no, it's fine! think you guys will do a better job than me, so keep going.
okay lets take an exapmle
what if u have 4 (2 + 3)
how much do u think that is?
I see so it means that the two in b+2 (b+ 2b) will be the only one who is gonna be multiplied cus it is beside the parentheses?
20?
30?
yes that is correct!
notice how we didnt do
(10 + 4) (2+3) that would be incorrect- and give us a way bigger number
remeber you distrubute the outside number that touches the () into the things inside
does that make sense?
for refrence it would be
10 (2) + 10(3) + 4(2) + 4(3) = 70 which is ofcourse an inccorect answer
I see I see, I really understand it now thank you so much everyone ๐ I really appreciate y'all help
Muchas gracias
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Ningรบn problema
Alr I'm back again, I'm curious, if the two in the 2nd to the last step were to be negative, would the equation be a minus?
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โ Original question: #help-10 message
Thank you so much ๐ฑ
nw
if a(x+y) where a is negative, we flip all the signs inside when expanding
-a(x+y) = -ax - ay
Oh I see, so it's always given then that it would be addition?
wdym
im not good at english can you please explain it more clearly
So if a were to be -, the sign that I circled would be an addition sign still if expanded?
nope
there is actually an implicit addition sign before each (3d+3) term in the original equation
which gets switched in case a < 0
What is an implicit addition sign?
implicit means that by convention its there, we just dont write it out
for example would you write +9?
nope
we write 9
the addition sign here is implicit
Ohhhh I see, I see, thank you so much ๐ฑso if a would be less than zero the sign would be minus ?
Let me know if I got it wrong
Which is it ๐ญ
nope ur correct i think
(correct but potential misunderstanding, hence both. I'm using this so as not to interrupt the conversation.)
Oke! Thank you so much! I may be back again soon cus I'm currently studying for college entrance exams, y'all answers weren't taught to us way back high school ๐ญ
Why so?
I'm baffled ๐ญ
you have considered the sign in the middle, but do not forget about the (implicit) sign in front of the first (3d + 3) as well.
if that 2 was a -2, then the RHS on the last line isn't just (3d + 3) - (3d + 3), but -(3d + 3) - (3d + 3). (note the extra negative sign out the front of the first (3d + 3).)
this was also why I โ ๏ธ'd the image and the message underneath, just in case.
because I did not see you mention the sign of the first binomial.
if you remember about the sign of the first binomial, then ignore the โ ๏ธ.
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how would i find AB?
u could split the triangle into 2 right angled triangles and apply usual trig
I think there might be a few different ways here.
law of cosines or law of sines are two approaches
oh, oops.
this is another approach
but yeah
whatever you recently learnt, i guess...
the 42 gets split into 26 right?
how are you splitting the triangle
splitting it in the center
yes, by drawing a vertical line on the center right?
yep
the angle on either side wont be affected by this split
the length u compute (x) will be affected if u use one half of the triangle
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How do you solve this graph? This wasn't in the tutorial
Well, y = 0.5x + 5 has what shape?
Is it a piece of circle? Is it a straight line? Or something else?
It didn't have a shape indicated๐ญ that's why I find it hard
Ohh I see
What do you know about equations such as y = x, or y = -x + 2 and so on?
In other words, what have you been taught about them?
Yess, I know about em. It's just my first time seeing that problem
well what do you know when x = 0?
Then x would be in the middle
middle of what
The cross :))))
umm
u can put it that way
now if you plug in x = 0 in
y = 0.5x + 5
what is the y value
Is it y=5 ?
yes
so that gives you a point
of (0, 5)
now what model is y = 0.5x + 5
Ohhhh! I get it :)))
Would that be linear?
yes
now look at A
is that linear and hit at the point (0, 5)
Oke oke! Lemme look at it again
It ain't hitting ๐ญ these answers gonna make my nosebleed
okay A does hit at (0, 5) however it is not linear
B doesnโt hit at (0, 5) but it is linear
now look at C
there isnโt a point of (0, 5) but
if you plug in x = 2
you get 6
which is shown on C
YAYYY WE GOT IT RIGHT ! What was the procedure to solve it
for me i like to make a table
so you notice all graphs is always positive
so you have a table of
x y
0
1
2
3
4
then you plug in for x
in the model
y = 0.5x + 5
and then see where it matches
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Let there be 3 people Donald, Jim and Tom. Also, let there be a bag containing 10 cards, 3 of which are winners. Given that Donald Jim and Tom pick cards in that order without returning their card, find the probability of each of them winning.
they all have the same chance
this is a fair game like what?
they sorta simultaneoulsy pick a random card, so 3/10 and 3/10 and 3/10
if they return the card, it's the same thing
no hold on
you got me
If they're NOT returning cards, the chance e.g. that Jim wins depends on what Donald draws
well you also have a chance of a previous person picking a winning card, letting the bag have 2/9 instead of 3/10
then theyall have the same chacne
i you look at the first three, they all the same chacne
but they arenโt returning the card
it all depends on the previous personโs card
But they literally don't
Donald draws a card and doesn't return it
they have the same chance ok
Whether or not he wins, now Jim has to choose from NINE cards
how?
If Donald drew a winning card, then Jim can only pick one of TWO remaining winning cards to win
If not, then he still has THREE cards to win with
because the first card hase 3/10 chance to be right
Neither 2/9 nor 3/9=1/3 is equal to 3/10
and 2nd card does
no it doesnโt
because they donโt return the card
so itโs 3/9
they have no advanatage over each other
No- the card DOESN'T GO BACK
ehh the last person does
assuming the previous people have not winning cards
3/10 * 2/9 + 7/10 * 3/9 = 3/10 so yeah its 3/10 no matter how you calculate
So there is no returning cards
you;re assuming the first person wins
But I got the answer its 3/10 for all
okay assume they donโt
the second person has 3/9 chance
so the second person has no advantage
since the card doesnโt go back
yes they do ๐ฅ
no, it equalizes
bro i donโt think 3/10, 3/9 or 2/9, 3/8 or 2/8 or 1/8 equalizes
You need to add the probability of the first person wins or not to find the second person's probability of winning
okay annoyingly the maths does hold out that it does come out to that
it doesn't even matter if the card goes back
second person has advantage IF the first person doesnโt pick a winning card
it does
But the reasoning should still warrant checking each case, imo
ok you geot me again
- its actually doesn't matter if first person wins, you can calculate directly if second drawed card is win
it comes out to 3/10?
if they win second person is 2/9
if they donโt win, second person is 3/9
3/9 > 2/9
.
so it does matter
hmm
you need to include probability of first then
Actually its possible to say that we shuffle cards and put them in deck, each person picks top card. Probabilities are same but for second person, question now is if second card is win, and its easy to calculate as 3/10, and we don't care about first card
Having the right approach to count these probabilities will help determine how to find Tom's chances, I reckon
Yes it does. You break it down into two scenarios
-# I cba to check otherwise
no you dont need scenarios if you do it like
We do because if its a win we remove it from the deck
this
if its lose card also removed no?
Yes. But those are 2 different events
i'm pretty sure it doesn't matter if the card is returned
-# fr
It does. Because the event of Tim winning is dependant on Donald winning
are you agree that
we shuffle cards and put them in deck, each person picks top card.
is same probability as original problem?
Coincidentally the probability is the same
Yes should be
so if we want to know if second person wins we just need to check if second (specific in deck) card is win, it can be done without checking cases for first card
But its random, deck is shuffled random, we just say that probability of each card to be win card is same
No its not a deck it's a bag
You take random cards form a BAG
Making it impossible to compare to a deck
So i was mistaken here
get 10 persons get each take random card -> bag become a deck of ordered cards
Its not ordered its a bag
Let's say me and you are playing
If i pull a card
And I win
Whats the probability of you winning?
Total is still same, since total is calculated before game
No because its a bag not an ordered deck
Please answer this
You need probabilities before game started, and prev outcomes doesn't affect next person choice (still random)
Yes it does
you run into Monty Hall problem if you think loke that
Still waiting...
.
See how it depends on if the first person wins or not?
if you calculate like that. I just showed that you can get result without cases more easily. you can check it is for 3rd it will also be 3/10 amd for next to
Well its still dependant. You showed that is dependant
i showed its not by calculating it differently and getting correct answer
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Pls DM me for more about this @abstract vortex
there is no computation needed to see they all have equal chance to win
. yh I did eventually notice that post scriptum
them picking in sequence is an equivalent process to them all picking simultaneously
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I do not see a T in the diagram
I don't even see a T
this has really put me off because. for other questions this would be the ideal drawing
now im questioning everything
how can it accelerate this way, according to the person, if the tension are opposing it?
im going insane
@slim ibex Has your question been resolved?
what's the problem?
ok so
you see the tension on the string
here
yup
shouldnt it look like this
because in other questions
it always looks like this
and now im really confused
I'm confused, where does tension act like this
it's always supposed to act against mg
because if ur pulling a string there will be tension along the string towards you
I mean if it's towards mg it's just 0
well you pull it with a Force 'F' to left direction, so tension acts on the right towards the pulley
so tension acts away from you?
tension is supposed to act against the force being applied, at least in a string
like doctorstrangejr said, tension acts in the direction opposite the applied force along the string at the end of the string
so in general could i just point the tension arrow towards the pulley/ pivot?
yup, pretty much always
in both a string and a rod
what if the masses were flipped? would tension still be towards the pulley? i.e same concept?
yes
yup, the concept is constant
the only variable is where the system goes, i.e. the acceleration of the system
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the tensions cancel out within the string, but the system as a whole will have a net acceleration once you consider all the forces. Draw the FDBs of each mass, and the combined mass of both, and you'll see
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Hi trying to understand the monty hall problem https://betterexplained.com/articles/understanding-the-monty-hall-problem/ The author writes "Hereโs how I visualize the filtering process. At the start, every door has an equal chance โ I imagine a pale green cloud, evenly distributed among all the doors.
As Monty starts removing the bad candidates (in the 99 you didnโt pick), he โpushesโ the cloud away from the bad doors to the good ones on that side. On and on it goes โ and the remaining doors get a brighter green cloud.
After all the filtering, thereโs your original door (still with a pale green cloud) and the โChamp Doorโ glowing nuclear green, containing the probabilities of the 98 doors."
I don't understand why that pale green cloud isn't distributed into the door I picked as well. Is it because Monty can't open the door I picked?
The easiest way to think abt this is with the classic Monty Hall problem
3 doors
behind one of which is a car
I like 100 doors more tbh
One can build to that my dear friend
I think 100 doors is easier to understand without some meandering prose about green fog
Meh
He does mention the 100 doors as well
With 100 doors, your initial choice has only a 1% chance of being correct, leaving a 99% probability that the prize is behind one of the other doors. After the host eliminates 98 empty doors, that 99% probability concentrates into the single remaining door, making switching the statistically better move.
Btw your initial choice cant be chosen by the host
Bc the door I picked hasn't been filtered
Ok cool
Yeah the green fog part confused me more
Try making the fog blue
It's just I am not sure I get it logically. Like yes I can make a weird variation of the problem with 7 doors, I pick nr 1 monty removes nr 2 and then the 6/7 chance of car concentrates into 5 doors.
Yeah no that explanation is pretty weird
But that's because you told me that the chance gets concentrated so I do that. Do you know another statistical problem that's tricky like monty hall? With filtering?
Maybe you can make one?
You can google the tuesday child problem for a famous problem with filtering
But thx for the help I appreciate it!
Though its famous because its unintuitive
All these problems are just conditional probability questions. Monty Hall is just a warning about your intuition spun into a story and then you are usually introduced to more formal mathematics.
Another problem is that John has 2 children, at least one of them is a boy, what is the probability the other is a girl.
Ahh shit I keep thinking its 50/50
how does at least one of them is a boy make that conditional
There are two children, so it is either BB GG BG GB
Then condition on the statement
Its linguistically unintuitive. Many people wouls interpret John walking up to them in a park and telling them one child is a boy. So the probabikity of the other chikd being a girl is 50โ naturally
But at least one is asking smth differently then that
If John tells me one is a boy I can remove GG and GB as possibility and I am left with BB and BG which gives me 50%???
Ok can you phrase it so it's linguistically intuitive?
In the set of all families with two children where at least one is a boy, what is the probability of the other being a girl
I still think of that other child as an independent event. Like when you make two coin flips.
My first child is a boy and at least one child is a boy are two different statements
at least one child is a boy = My first child is a boy and the other child is maybe a boy?
Well lets do coim flips then. Lets say we flip a coin two times we have 4 equally likely outcomes.
HH
TT
HT
TH
Now im telling you at least one is head. But I havent told you which of those two coin is head. Ao we can exclude TT because if at least one is Head TT cant be true we land with: HH, HT, TH
Ohhh they are pairs!
Now imagine Id say the first coin is head we would get at the end: HH, HT
So the chance for the second being Head or tails is 50โ
That helped a lot!
Ok at least one is head but it doesnt specify first or second, that makes sense.
Okay how would you calculate the probablity if you did pars of 10 coin flips. I don't want to write it all out
Ah I only remove the one with all tails
thx JordenJost!
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From 9 students, 4 of them wear glasses. if 3 students were chosen at once, what is the probability that:
a. all 3 don't wear glasses
b. 2 of them dont wear glasses
c. at least 1 of them wears glasses
can someone help explain to me how to do this?
Where are you stuck
like
from what my teacher said
i'm supposed to use a formula which looks like this
i THINK i can do the first question, but i'm not sure with the second and third
Binomial distribution
yeaa that thing
what
It's much simpler than that
what am i supposed to use?
for b you will probably want to use that
like with the formula i think a looks like
9C3 (5/9)^3 (4/9)^0
so
9!/6!3! x 625/729
84 x 625/729
and boom i think i put in the wrong number ๐ญ
,, P(A) = \4{\t{number of favorable outcomes}}{\t{total number of possible outcomes}}
How many ways can you select 3 students from 9 students?
Yeah
So thats the denominator here
For a, you want to choose 3 students from a group of 5 that doesnt wear glasses. How would u do that
Yea
Yea
ok so
9C3 x (4/9)^2 x (5/9)^1
like that?
9!/6!3! x 16/81 x 5/9
84 x 16/81 x 45/81
60480/6561
what
Yeah no
Maybe its better to just stick with this for now
uhuh
ok
How many ways can you pick 2 students without glasses
5!/3!2!
10
Yep
then from the one wearing glasses
Complement
1 - (5!/2!3!) / 84
1- 10/84
74/84
37/42?
You nailed it
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Did it for you
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Hello, i am struggling to understand what it is asking me here. I cannot figure out where certain bits of informations are missing, how to find them, and its getting compounded with this platform that does not explain anything well at all.
it's asking you for the sine of that angle, by hand, presumably by constructing special triangles.
i need help in converting 2 complex numbers from triogenometric to rectangular
or, well, one particular special triangle.
!occupied
Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #โhow-to-get-help for instructions).
what exactly are you struggling with
do you wish to take over?
if so I'll just take a step back.
sure
okay.
like, most of it... Im know that the radian measure ends up pointing down, but i am unaware of how to figure out the quadrant the triangle always ends up in. Would this specific one be in the double negative quadrant?
are you aware of the ASTC mnemonic?
i am not
do you know how a coordinate on a unit circle is given by (cos(theta), sin(theta))?
i think.. sin represents y and cosin x?
yes
cool
so what you should do here is
figure out the value of sin(-11pi/6) and the sign of it
do this by first considering -11pi/6 as a more familiar angle
when you have a negative angle, you can repeatedly add 2pi to it until it becomes posaitive
using unit circle?
yes
because adding 2pi (rotating 360deg) brings you back to the same position
so it has no effect on the value of sine or cosine
what is -11pi/6 + 2pi?
joy
,w sin(-11pi/6)

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no it's closed dw
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this answer makes 0 sense to me
so is it saying that if 99 out of 100 samples gives a sample proportion as high or higher than the one obtained i would not reject the null hypothesis?
why?
thats just the definition of p-value
just the probability of obtaining data as extreme as observed, assuming the null hypothesis is true
in this case your pvalue is 0.21
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Hi. I've been assigned to find an example of a triary complete code with word lengths ${a,,b,b,c,c,d}$, respectively, such that $1 \leq a<b<c<d$. I'm struggling to find one that satisfies the Kraft equality and been searching online for a while with no luck.
Gol D Roger
Gol D Roger
is it really a, b, c, c, d or just a, b, c, d?
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โ Original question: #help-10 message
Like that, ${ a,b,b,c,c,d}$
Gol D Roger
I forgot a $b$ there
Gol D Roger
Gol D Roger
The word length is a,b,b,c,c,d?
For each word, correct
So isn't you can transfer them into: $3^{-a} + 2 \cdot 3^{-b} + 2 \cdot 3^{-c} + 3^{-d} = 1$?
Mercury.
How can I proceed to get there?
You got this sum here.
So which means you can just expand the sum.
And since we were given: a<b<c<d, then we can see 3^(-a) is the greatest contributor.
You just substitute a,b,c,d in l_i.
Hope this make sense?
Ok, $3^{-a}$ is the greatest contributor, , but I can't see how to substitute
Gol D Roger
Yeah, but more specifically, like, giving values to a,b,c and d
Should I just try brute force?
<@&286206848099549185>
Are you sure the inequalities are strict?
I'm backing up Mercury that this is impossible. A complete ternary code corresponds to a strictly full ternary tree. If you start with 1 root node and continuously branch it to 3, then the total number of leaves will be 1+2k (where k is the number of internal nodes). But your proposed set of word lengths is exactly 6 words, and 6 is not odd.
@reef gyro
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