#help-38
1 messages · Page 95 of 1
AWACS Sky Eye
after some more work, i'm at the point in the video but now i don't know what to use to recalc limits
so since we know u = 1 + 9x^4
we just plug in the original bounds into this equation
to change the bounds so that it follows u
...huhn. thanks.
the reason why we can’t use the original bounds is because they are what x is equal to
we have to change everything to u when substituting
since we are converting everything to in terms of u
$$
\begin{aligned}
2\pi&\int_0^5x^3\sqrt{1+9x^4}:dx \
&u=1+9x^4\qquad \frac{du}{dx}=36x^3 \
&a=1+9(1)^4\qquad a=10 \
&b=1+9(5)^4\qquad b=5626 \
&\frac{dx}{du}=\frac1{36x^3} \
&\int_a^bx^3\cdot\frac1{36x^3}\cdot\sqrt{u}:du \
\frac{2\pi}{36}&\int_a^b\sqrt{u}:du \
&\int_a^bu^{1/2}:du \
\frac{2\pi}{36}\cdot\frac2{3}&\biggr[u^{3/2}\biggr]a^b \
\frac\pi{27}&\biggr[u^{3/2}\biggr]{10}^{5626}
\end{aligned}
$$
AWACS Sky Eye
this doesn't look right, and it's not right at least when i put it in.....
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hello
it doesn't matter
you can have 1,2,3,4,5,6 instead
possible explanation is that in programming everything is 0 based, so it might be a habit of your lecturer to start with 0
but in general it is often conventional in math to have a 0 based list
but i digress, in this case it doesn't matter
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what if i had 1/sin(x) on (0,pi/2), its continuous on that region, but it has no maximum
ahh
the closed interval & continuity leads to the existence of minimum/maximum on that interval
which is why it's a requirement for you to use it
oh ok
I gotta leave for around an hour maybe more..
I'll be back tho!
hopefully bot doesnt close channel
sure, occupy as you wish
well it will
if you want to ask more about the above images just copy them into your dms
then you can use them later too
@obsidian hornet Has your question been resolved?
@obsidian hornet Has your question been resolved?
okk Im finally back
a continuous surjective map doesnt mean its surjective right?
wait no
continuous surjective map means its continous and surjective by the name
But if we are given the fact that the function is continuous and surjective, then it must have a min/max even if its open bounded
so heres the question
what Im thinking rn is I can apply the Intermediate value theorem, even if its open intervals
because I can find a limit as x approaches 0 from right
and limit as x approaches 2pi from left
limit exists
right so, to prove its not a bijection, I just have to prove its not injective because its already given that its surjective and continous
but for it to be injective, you CANT have two values in the domain to map to the same value in the codomain
so Im thinking then by IVT I can find such c where the limit also goes to 1 or -1
These are just my thoughts for now...
Im still working it out
IVT I can find such c where the limit also goes to 1 or -1 <- this part is just an assumption so Im gonna try finding more info about this
@obsidian hornet Has your question been resolved?
well, IVT is a good idea for sure (noting the continuity of f), and...
...yes, you do know that f has a maximum (of 1) and minimum (of -1), and must attain those somewhere by the surjectivity
If you haven't gotten an idea yet, hopefully those two statements should do it 
Hello! yup Im working on it now
after sending my last message I left to eat food😅
if f maps the interval (0, 2pi) onto [-1,1], -1 and 1 would be attained once in (0,2pi) if you suppose injectivity
and surjective just means all y in [-1,1] gets mapped by x in (0,2pi)
Sure to both, though you may find it easier, rather than assuming injectivity to contradict it, to directly show that there isn't injectivity 
how can I show that more than one x in the domain maps to the same y in the codomain...
id have to show -1 and 1 could be attained more than once in(0, 2pi)
Not necessarily -1 and/or 1 need to be attained more than once-
As per before, you know that -1 is attained at least once, say, at the point a (between 0 and 2pi exclusive), and that +1 is attained at least once, say, at the point b...
You have either a < b or a > b (you can assume either without loss of generality), but with that, you can make use of those and something else you know 
IVT, so there exist c in (a,b) s.t c=k if f(a)<k<f(b) (or > it doesnt matter)
Yep, in other words, between a and b, you attain all values between f(a) (= -1) and f(b) (= +1)
But then, there's something slight I had mentioned before that's quite important, see if you can figure it out 
right but you can also find x outside [a,b] wich is a subset of (a,b), and that x also maps to some y in [-1,1]
proving it is not injective
Yep, that's basically the idea 
On the interval [a, b], f attains all values between -1 and 1, but then, you have a > 0 and b < 2pi, so there are some elements in the domain you haven't "used", but you've "used" all the elements in the range already - you basically have to "reuse" some values
ok
thank you
ahh now I gotta write it down
thats the hard part too
cause its hard to get ideas down on paper
at least for me I think
Awwww
yea it can be hard to write out the ideas properly sometimes, even when you can see how it'd work and have the ideas 
yuppp
I definitely need more practice on proof writing
I take wayyy too long
@whole coral Im wondering if you could help check?
Of course 
oh no i did smth wrong for sure
You haven't! The comments I have are mostly "grammatical" more than anything 
I would say that to make clear that a is one of those points where f attains the value -1 (and similarly b and +1)
I would also restate the IVT part: basically more phrasing it that "for any k such that f(a) < k < f(b), there exists a c in (a, b) such that f(c) = k"
But you have it 
Just tiny things to make it pretty clear what you mean 
(also another really tiny point, I think I would say in the sentence "f attains all values between -1 and 1 on the interval [a, b]" to make it clear that it's within that subset of (0, 2pi) that you've attained the values in the range, making it clearer about the later part that you're not injective, but not super essential I think
)
there!
thank you soo much
I really appreciate the help
and you're also very good at explaining stuff
Wonderful 
Awww
why thank you 
Always a pleasure to work with you 
ohhh
wait I missed smth
its f(a)<f(b) cause I stated -1 is attained at a
so I dont need the w.l.o.g stuff in the brackets
Yeaa you know that f(a) was -1 and f(b) was 1, or at least chose a and b such that those were the case 
You could, instead, have "fixed" a and b such that a < b, then let f(a) and f(b) be either -1 or 1, then do the without loss of generality there 
Awwww
you definitely should, if you need one 
ahh my friends are asking me to go out with them
do I go do I nottt
i love staying in😂 but also i should socialize too
Awwww
I would say that you should go out
though I'm a bit biased maybe cause I wouldn't mind going out myself 
It is nice to stay in for sure though 
ye I was gonna just call up a friend and just chill at their place
but they're not picking up
so prob gonna go out LOL
okkkkkk
bbyeeeeeeeeeeeeeeeeeeee
thank yuouuuu
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.See ya laterrrrr 





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i literally have no idea how to do this
Take two points, sub them into the equation.
This gives two equations with two unknowns. You want to simultaneously solve.
Find k before you do that
Or if you really want you can sub in (infinity, 4) as a point but you have to be on some crackhead level shit for that
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need help with a
idk if i’ve done it correctly so far but not sure how to find c
cuz x-4 is a factor so if u input 4 into the eq it will = 0
i understand the factor and remainder part, just unsure of what to do since it’s a factor of f(x) and not f’(x)
it says that for f(x) but the given equation is f’(x)
does that change anything
factor theorem la
plug x=4
i think u can work out f(x)'s equation with the 2 factors maybe
set qual to 0
does it matter that the equation given is f’(x) (derivative) and not f(x)
f’(x) is given but it’s the derivative, no?
you can integrate to get f(x)
i’m trying to do that as my work is shown in the screenshot but how do i get rid of c or find it
ohh it will make simultaneous equation if i use x=-1 and x=4
remainder theorem again
and using that i can subtract them to remove c?
system of equations in a and c
solve
voila
x+1 is not factor btw
i meant x = -1
((ax^2)/3 - (7-4a/3)x + (28 - 16a/3)) is when you / f(x) by (x-4)
Also is that your dog in your pfp
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Given f(x). Find the value of f'(0)
Did you try differentiating f
Ohhh
and replace x with 0 for f'(0)
Idk what to do now..
chain rule
My handwriting looks terrible
,rcw

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fiind surrface area of each of them
yeah, you don;t need to get it to find the areas and divide
then use the formula,
%difference = ((areaBIG - areaSMALL)/(areaBIG)*100)
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You still need help? @candid valve
@candid valve Has your question been resolved?
I integrated wrt x after integrating wrt y
oh
if you integrate x²dxdy wrt y then will it be x²y.dx?
it's between the limits y=x and y=0, so I get x^3
Wait, I haven't learnt double integral
Helpers might help
<@&286206848099549185>
Here's the question
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hello please
i need elp
not really specific math hlep but rather on studying the subject any advice
what kind of help?
when im studying math
i seem to spend a l ong time answering a small amount of questions
when i mean
a long time
i will time myself while im solving the questions
but i will spend a long time wit the teacher
it is completely okay
it's okay
as i ask a lot of questions about math questions
sometimes ı spent weeks just for 1 question
That's a good thing!
if you can't ask you can't learn
ı didn't see you were handling,sorry mate
So you're taking more time because you are learning new concepts!
It's okay mate, we're both trying to help
but my problem is other people can solve 10 20 30 questions without struggling immediately after a class
So it's completely fine
It comes with practice!
and it seems other peole are getting a nice reward for studying less
no right after a class
Well you know what?
you cannot know that
They might be studying at home
god's gift then ı shall say
Then what's the problem here?
It only means that they can apply those ideas more quickly than you
What do you consider as being good at math?
but i need to solve more problems
bein able to solve a lot of problems
and be creative in solutions
Yes you can say that
Exactly!
Solving more questions in less amount of time is cool
but i want to go for math olympiads someday
But having a solution which is beautiful is ever cooler
and i canat go if i spend absurd amount of time solving questions
let me give you an example. ı have a friend that solves questions for real slow. Like when he solves 1 ı solve 5 question hovewer, he always takes the most efficiency from that questions and beats me in any test. So rather than numbers, you should focus on efficiency you get from studying sessions.
You can! You just need to find the right mentor and you need the aptitude
wait
how
For math or olys for any subjects, i would say what's most important is the passion for math
yes i have that
Then As long as you're passionate about the subject, then you will enjoy the process
gokadam can you please share more light on thsi
I just solve questions. but he creates other scenarios from that questions and think about them. he doesn't answer and skip like me
but it not only math its physics
that what i do
but my people just criticise
They are almost the same! What I say applies to both or more of them!
As long as you're passionate and don't care about what others say (in a good way), then you're going right!
have you guys been to university
In my opinion, you're going right
You have the passion and you ask questions, so it will be fine for you
no, but ı know unversity lessons
No, but I know a lot of topics
YES
A LOT
we are the same person fr
Like a say a LOT, I spent like 2 hrs solving 2 questions yesterday
And that of math kangroo of class 8
GRADE 8, when I'm going to grade 12
So it doesn't matter to me
But they use the same concepts right?
yes but olympiad math is more twisted
What's the difference? Only the difficulty is different?
Not every questions
@topaz imp what I'm trying to say is
You're going in the right path
Yes it does
But it's not "that" necessary
as im not creative
If you're passionate about math, then you should spend time solving more questions
just don't hesitate and doubt yourself. keep moving and you will be succesful for sure
Be it school math or Olympiad math
And you could ask your math teacher to be your mentor
He will definitely help!
Also There is a whole math server dedicated to it
ok
spending more time on questions is cool btw
it's not something you should be ashamed of
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"At the party, there were 8 girls and 13 boys. How many different pairs can be formed for dancing, if all the girls must participate in the dance?"
Note: Dancing pair can only be formed by one girl and one boy. There can’t be two boys or two girls in one pair
@wraith hinge Has your question been resolved?
13C1×8C1 ?
Well maybe
I looked at it this way and not sure why that would not work
Wait imma send
Ok
For first group there are 8 girls avalible and they can pick one of 13 guys (104 possibilities)
In second group there are 7 girls left and they can pick one of 12 guys (84 possibilities)
In third group there are 6 girls left and they can chose one guy from 11 guys left (66 possibilities)
and so on
And then we just do 104 + 84 + 66 + 50….
Why would that not work?
My friend said it’s done like this
We find out in how many ways we can pick 8 guys from 13 guys and just multiply that by 8 girls
Well your logic is some what correct
Yep I think this is better, you know this is same as ur logic
You tried using similar method as we do for finding number of possible numbers formed right?
" 8girls available can pick any from 13boys" u are actually pairing them all not just one girl
Thats why when one girl picks a guy, another 7 girls can pick one of 12 boys remaining and so on. Why can’t i pair all the girls that way?
Oh
I got it
Sorry
Never mind
Yeah
So u understood?
Yeah
Did u get this btw
Aight then
Let me try something one moment
I get why this doesn’t work
I don’t get why this works
Could you try to explain?
So there is basically two places left to be filled up since we need to pair up
Since number of ways of filling girls is 8 itself it is given the value as 8
But number of ways of filling boy is yet to be found
There are 13b we want just 8, they can be anyone from these 13, therefore 13C8
ways of filling boys space
Also doing it this way, does it matter if let’s say Anna and Mark are in group 2 or group 4.
Does it matter what group they are in or is it just important that they are in 8 different groups
Just think of it as numbers forming problem
8 diff grp
How would this be done if it doesn’t matter what group someone is in. Sequence of groups is not important
It is just important that they are paired in 8 groups
wdym exactly
I mean if Mark and Anna being paired in group 2 is same as Mark and Anna being paired in group 4
8 different groups?
It's not like this, it is still one group
But the problem would have to be solved differently if sequence of group mattered
There would be just 8 possible groups
If they mattered ig
Since u want particular boy and girl in a particular grp
Same girl matched with same guy everywhere
But in different groups
How would problem if this counted still as same thing and how would problem be solved if this was counted as not same thing
Is my question making sense
I'm trying to understand
This is not what the question is asking
But that's what I mean there will be only 8 such groups of ur desire
The question is asking:
Any boy + any girl
As someone whose english is their second language i am having barrier in trying to express my self xD
So mark can be paired up with cherry
I am not asking that
It's okay! I can understand what you are trying to explain though I g?, since it's my second language too it's not easy for me aswell
Okay let’s pretend that group 1 goes to one one room
Group 2 goes to another room
Group 3 goes to third room
And each room is different
That way
Okay and
If mark and Jenna got paired INTO group 1
They would to for example room that has tv and cool music
But if Mark and Jenna got paired into group 6
They for example go to room that has vegetables and stinks
Lol
So even if they paired same way
It matters if they got paired into group 1 or group 4
But now
But I don't think it means anything as grouping them is 1,2 or 3 group numbers
Let’s say that EVERY SINGLE group goes to room with vegetables that stink
It's just they have to be paired
So now it doesn’t matter if Mark and Jenna got paired in group 1 or group 4
Because it is SAME thing
Correct
It is same thing if they got paired together in group 1 and group 4
But if rooms are different it is not same thing
So how do you solve problem if number which group they are in matters
And how would you solve if it doesn’t matter what group they got sorted into it just matters who paired with who
It is , we are not finding 'number of ways to put the pair in a group'
After pairing them it doesn't even matter which grp they are
Okay
Well I don't really understand this much
So my problem from beggining
But some other helper might help you!
Was that it doesn’t matter what group they are in
Just matters who got paired with who
Just matters if they are paired or not
Yep I think so
Sure lol
I understand better now
I'm anyways going to sleep, it's midnight here
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answer for this ?
<@&286206848099549185>
most of the configurations are basically the same, so just draw it out and count
or ask how many lines each even one hits
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How can sum-to-product identities be demonstrated?
Take the identities for cos(a+b) and cos(a-b)
solve them simultaneously for cos(a)cos(b) and sin(a)sin(b)
Change the variables around by substituting.
You get the first two identities
These are really just the sum identities in reverse
bro, go to another channel XD
You tell me to do something like
cos(x)+cos(y)
x=a+b, y=a-b
cos(a+b)+cos(a-b)?
Do you know the identities for cos(a+b) and cos(a-b)?
Start from cos(a+b) + cos(a-b)
This is already looking suspiciously like the top identity
then?
Let a = (x + y)/2
And b = (x - y)/2
I don't understand the why and how of this change of variable
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I’m stuck on this problem
The hint is to use F(r)=c/r^2
@pure oak Has your question been resolved?
@pure oak Has your question been resolved?
@pure oak Has your question been resolved?
@pure oak Has your question been resolved?
@pure oak the problem is simply about setting up the integral, because it specifies not to evaluate it. Do you recall the integral form of work?
I think it's just the definition of the definite integral
If so, then use the integral form of work, you just need to specify the integration bounds, and the function of integration, which you already have
$\int_a^b F(r) , \dd{r}$
OmnipotentEntity
Ok, so c is going to be related somehow to the mass right?
What is the force due to gravity?
Mg
OmnipotentEntity
Where M is the mass of earth, m is the mass of the object, and G is the gravitational constant.
The way the professor would do it is F(4000)=c/(4000) ^2 and he lets F(4000)=weight of space module but this doesn't make any sense
That way does make sense
Because you know what g is on the surface
This allows you to find c.
And then you can reuse c
Both methods will work
How is the way you would approach this particular example
I would suggest using the professor's way, it seems easier, uses fewer facts.
I'm okay with using their way but why does F(4000)=10
It's input is 4000 and output is 10
For the second part I'm confused at is the bounds of integration
I would've said from 0 to 1000
Reason I say that is because it says "How much work is done in propelling the module to a height of 1000 mi above earth"
Honestly I'm not used to seeing integration this way, I'm used to it being area under a curve
It is here as well
The curve is force vs radius
It's just a little bit more implicit, and you have to go out of your way to graph it
That does make sense
I guess that's it for this problem even though it makes absolutely no sense. Thanks for all the suggestions
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how would i write a polynomial function with least degree and leading coefficient of one given the zeros 0, root 5, 2
is it just f(x)=x(x-root 5)(x-2) then factoroed out, but my worksheet says the factored out function starts with f(x)=x^4....
!original
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.
your attempt is correct unless you missed a detail in the question
I think you’re missing the root part
When the zero equals a root shouldn’t it be + and - that root or am I wrong
Ohhh I did this in precalc
Hold on I know I’m wrong now
only if you need the coefficients to be integers / rational numbers
if you don't care then you don't need that
Oh okay
so how would i write this function, because from what i know the highest exponent is how many zeros there will be no?, so you would think it starts with f(x)=x^3 but its x^4
x^3 is correct
they probably wanted rational coefficients, in which case you would need x^4. but they didnt say that, so whatever
is what the school says is the answer
They made -√5 also a root to get this
weird, ill just write it assuming theres only 3 cause they didn't give -root 5
that's alright
if you want only rational coefs u need -sqrt 5 too
if ydc, then yea u dont need -sqrt 5
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next question they say the zeros are 1, -1(multiplicity 3), and 3i
so you would thing it would be like f(x)=x^5 yadadada, but
Show the actual question
is the answer apparently
they (again implicitly) want real coordinates
so if you have a complex root you need its conjugate as well -- again this is them not specifying it. your answer is perfectly fine
ok give me a minute i wanna write it out
so pre distributed it would be f(x)=(x-1)(x+1)^3(x+3i)(x-3i)?
yeah
took a little bit on paint cause i dont have a notebook/whiteboard with me, but i got the answer, so i guess if its a root or imaginery i gotta assume its +-
if you want integer coefficients yeah
hay²le
so is this stuff actually precalc cause that is not the course im taking
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i need the help:( i feel like im missing something. its top to bottom yeah? so √1-x^2 - 0?
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ab and ba numbers(they are two digits not multiplied) and If ab + 24 = ba what is a+b?
on the other hand, trial and error could also work
so we try every possbility?
algebra?
9b = 9a + 24
we know that they're one digit numbers
one possibility
wait no mb
hang on
lemme try again
so was 3b=3a+8 wrong
i gues you didnt multiply it by -1
??
no wait you did
lol
it's not possible
yea thought so
I guess i created the formula incorrectly
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.
In the real question, it says ab is minute part of a digital timer and after 208 minute minute part is ba
there is no picture in the question
so it's like ab+24 = xba
not even like that either
oh i see
so i thought we need to do that like 208 minute is 3 hours + 24
so we dont care about hour etc.
so smth like
minutes since midnight = 60H_1 + 10A + B
60H_2 + 10B + 10A = that + 208
oh wait it was actually 204
not 208 mb
so it is definitely 3 hours + 24 minutes
got it
maybe we need to do it like: ab+24-60=ba ?
or im just making up formulas
*equations
what if ab+24 is higher than 60 then that would be in hour
how?
just thought of random numbers
if it went past 60 we could say that the number is something like 36, or 69
b=a+3
because it doens;t go past 60, there are other options
If we think it logically and think sum of minutes the equation must look something like: ab+24=60*k + ba
does it make sense to you
k is natural number
k is 1 or 0
i don't know how to do it logically
actually wait
there's maybe 2 answers
yeah, there's 2 ways to do a=b+4
they both work
then whats a and b?
we can't tell
a+b?
it could be 40 with sum 4 or 51 with sum 6
there must be answer the test says there is 😄
what are the numbers you used to make 6
51
correct answer is actually 6
but so what i learned from this question 😄 trying every possbilitiy?
I was supposed to solve this in 1.5 minutes
well yeah
you got a=4+b from assuming k = 1
and it gave you an answer
and it's sufficiently smart
I guess i need to make most simple equation then try every number from 0 to 9 fast
they always ask questions like this in a exam in Turkey called TYT
it's like SAT but its harder
so wait, there were like 4 options?
and there was 6 and there was no 4?
options are 7 6 5 4 3
but how can we get 4
40
okay
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i can see a whole proof kinda
so first we assume a is in {1,2,3} and b is under {1,2,3,4,5}, so nothing rolls over at all
this is a contradiction, both a and b will increase in that case, they can't become equal to ba
bro is on his way to prove test is wrong
no it's fine
nothing wrong in this one
basically you can show that "ab+24=60 + ba" holds, that it rolls over 60, and then it's solveable like you said a=4+b
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whats happening here
for the reject
i dont understand why they rejected it
wait nvm i get it now
but im stil confused on how they got the blue part
Draw line x=1 on the graph and it should be clear
oh shit
oh ok
so blue goes to where red's x-int is
from 0 to red's x-int
and then red goes from 0 to 1
@turbid leaf is that right
i dont understand why its addition tho
shouldnt it be subtract
wait no im wrong again
its blue from 0 to 1
add red 1 to its x-int
why are they doing pinks area liike this
is it just easier
@turbid leaf
Yep
so i can technically do it both ways right
Yeah you can
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During the last drought, the water table dropped so low that three villages in the plains ran out of drinking water. The council organised a light duty tanker to carry water from the main reservoir to the villages on a weekly basis.
At the start of each trip the tanker was always full of water; unknown to the driver, just as he started driving from the reservoir, the water tank developed a leak. By the time he reached the first village, the tanker had lost half of the water from the water tank and consumed half of the fuel tank. You can assume that the fuel consumption of the truck is directly proportional to the weight it carries, and that the water flow (in the leakage) and the speed of the truck were constant for the whole journey.
We also know that an empty tanker uses exactly one sixth of the fuel tank when travelling from the first village back to the reservoir.
Disregarding the fuel tank weight, what fraction of the fuel tank would be spent to reach the first village when the truck had no leak?
i need all the assumptions you made while getting this answer too :3
as long as its logical it works
@past sinew Has your question been resolved?
I think it's 1/3,
as total = 1 + w
c(1+w) = 1/2 + c(1+w/2)
c = 1/2w
1/2w = 1/6 ( empty tank uses one sixth)
w = 1/3
<@&286206848099549185> its been 15 >.<
im just wondering if it looks right
whatas the qns
.
Disregarding the fuel tank weight, what fraction of the fuel tank would be spent to reach the first village when the truck had no leak?
Assuming proportionality of fuel and water weight, no changes in the conditions that could change the rate of leakage, uniform speed of the truck
woukld it be just 1/2 the tank tho
like the fuel in the tank would have been spent since when it satrts at the resevoir it has a full tank
n when it reaches the first village it has lost half of the water from the water tank
since the fuel consumption of the vehicle is directly proprtional to the weight it carries
if it loses half water of the tank then it loses half of the fuel it contains
assuming the water density remains constant
yeah but that's half of the fuel and water including the fuel it takes to travel to the first village
which is 1/6
so the total fuel used to get to the first village is 1/2 - 1/6
and if that's 1/3, then the water should also be 1/3
well
yes u are right
if we saying the truck has no leak then f+1/6=1/2
thus f=1/2-1/6=3/6-1/6=1/3
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in vector calculus for curvature of a circle to a curve, k, with starting at r(t), and where T=r'(t)/|r'(t)| i have 3 different formulas. are they all interchangable?
k=1/|v| * |dT/dt|
k = |r'(t) X r''(t)| / ( |r'(t)|^3 )
k = |T'| / |r'|
i know 1 and 2 are but is 3?
yea 3 looks like 1 rearranged a bit
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Learned about permutations, at 12:10 they give us the problem of finding the order a 2 cycle, 3 cycle, etc;, but the order of an element x is the power required to get the identity element, but what the hell is the group and identity element in this case? https://youtu.be/MpKG6FmcIHk?si=U-loF1EP97f834jw
Cycle Notation gives you a way to compactly write down a permutation. Since the symmetric group is so important in the study of groups, learning cycle notation will speed up your work with the group Sn. In this lesson we show you how to convert a permutation into cycle notation, talk about the conventions, and discuss the key properties of cyc...
Wait the group is the symmetric group and e is (1)(2)(3)…(n), but how do i find the order?
You have to multiply element to itself unless you not get identity and it is that elements order
Here group is one to one and onto function to a set to same set
Like if A={1,2,3,4}
Then all the one-one and onto function from A to A is the symmetric group
And identity element is if
1 goes to 1
2 to 2
3 to 3
4 to 4
You mean until you get the identity right?
Ya
Is there a specific symbol for the identity?
Ya we use epsilon which is not in my keyboard
So for 2 cycles the order is 2 (i did it mentally) and according to google the order of an n cycle is n but how?
Basically function composition right
Group we working on
Ya
So what the problem you can calculate order of 2 cycle
By function composition
Yh but how do we prove the order of an n cycle is n?
Nvm i did some examples by hand and got it
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I am trying to do by induction method @tame hemlock
Aight i’ll reopen post the proof when you’re done thanks
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Sorry I couldn't do it ,i see in books it saying verify yourself no proof
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the largest eigenvalue was 3. I understand everything except why did the solution add
0
1
0
even though it's not in the null space? i thought the null space is only:
-2
0
1
@urban jungle Has your question been resolved?
When we express the solution set in terms of the free variables, we include a vector for each free variable where that variable is 1 and all other variables are 0. This is a standard way to express the solution set of a system of linear equations.
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Don’t rly understand what associated symmetric matrix is
You should be able to write that as x^t Ax for some matrix A, and letting x = (x1, x2, x3)
They’re basically asking you for that matrix A
@smoky kite Has your question been resolved?
Good question
erm…
Well you already know that the matrix A has to be symmetric at least, which makes your life a bit easier
And because you have the x1, x2 and x3 terms all appearing squared, the diagonal entries you know
But then you also have an x1x3 term, so you wanna be able to get that 
That would imply the (1, 3) (and by symmetry, the (3, 1) one as well) are nonzero, but then those entries will contribute two factors of x1x3
If any of that seems to make sense? Rather annoyingly I haven't found any resources or anything that explain it better than me
@smoky kite
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can someone explain the induction they did on this
I feel like it was done in a kinda confusing way, but i could be overlooking some things
also, im ngl to prove it is well defined cant you just use the well ordering principle
@fringe marsh Has your question been resolved?
<@&286206848099549185>
it's tricky because it's both a contradiction and induction proof. for the contradiction they have to search through all of P(N) for a set that has no minimum, and to do that they induct on sets with k in them and work their way up
so like the base case covers sets like {0,5,9}, {0,3,4,6} etc. and for the next step they look at sets with a 1, but none of the numbers less than 1, such as {1,2,3} etc.
and the proof logic is that they try the obvious minimum, k, but the induction hypothesis contradicts this so apparently you can't pick any k in the A and A is empty, for all sets A in P(N)
i hate that
no chance i would have thought of that on an exam
is there a more uh smooth solution
thanks for explaining btw, makes sense.
yea I wish there was, but I think the only way to super rigorously prove this is with induction
thank you for explaining, im going to try reconstructing the proof myself (and btw thank you so much for helping me these last few days, really really appreciate it)
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I’m trying to understand the concept of a sequence of events happening infinitely often (in the picture shown, please disregard my markings). I’m confused about the set intersection/union definition.
image cut off above
I made a toy example, where the sample space is infinite coin tosses and events A_i denote whether there is a Heads in the ith position of each sample point
The set definition of i.o. is A_1 intersect (A_1 union A_2) intersect…
but i can’t really make sense of this
can i get an explanation of how the set definition applies to my example?
namely isn’t this long intersection just equal to A_1?
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What do u need explained
?
nvm
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Not enough data methinks
i tried that way but couldnt do much either
im kinda lost
<@&286206848099549185>
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what is this notation and what does it mean
Need more context
how it's used in algebra
it looks like a screenshot of a part of text you were reading and you dont know what does it mean
maybe send a pic of all text?
so we get a more context
without context this notation might be used in variety of situations
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I need help setting up my triple integral in cylindrical form. I don't know what my bnounds should be on my radius, I've never done an elliptical cylinder before.
@fallen jay Has your question been resolved?
<@&286206848099549185> please
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@fallen jay Has your question been resolved?
x
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F = mv/t
It doesn't say how long so lets assume 1 second
F = 90*2
F = 180N
since force is preserved it is the same for both of them
180 = 60v
v=180/60
v=3ms-1
yeah
F is force in newtons and t is time in seconds
F=ma a = v/t
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Calculate lnS(x) at x=1.5. With S(x) being the sum of the series ..... know ....
I calculated that the answer to this question is A, someone please help me check the answer
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*cái đề
chao xìn
thực ra tôi cx ko biết giải:)))
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Hi, could someone help me figure out what are the total possible concatenated numbers?
@astral ore Has your question been resolved?
<@&286206848099549185>
@astral ore Has your question been resolved?
THe main ideia is to multiply the 10 numbers than X can choose with the 50 numbers of Y and the 100 numbers of Z to get it
it's only 10 numbers for X lol


