#help-13
1 messages · Page 164 of 1
Okay
Tell me what you find
nnnnope
nooo
Yes it is
You want y to be minimum
Yes
y=u-v
0<=u<=2
0<=v<=1
0-0
u=0 and v=1
-1
Is this sort of like Jacobian?
So what work do I erase and work do I start writing
what do you say!
Max of y is 1
Nooo
2?
yess
1
right right
There you go, you have them all
$$0 \le x \le 3$$
$$-1 \le y \le 2$$
$$1 \le z \le 6$$
why is this significant?
LUNA
Because
When you divide the integral into 6 integrals
Each integral will have its own bounds
depending on the face
of the paralellogram
6 double integrals
6 because paralellogram has 6 faces
and double because it is a surface integral
takes forever honestly
that's why the divergence theorem is used
my professor said
idk
for the final
we can use either stokes theorem or divergence theorem for one of the problems
whatever we are more comfortable with
so divergence theorem is prob the more comfortable one
for our final boss problem?
That's awesome!
Yeah, look
instead of computing 6 double integrals
and involving vector fields and normal vectors
you only do 1 triple integral
involving SCALAR field and no vectors
Actually divergence theorem sounds kind of nice
i have a picture of it, wait
Oh you know it!
I haven’t watched that tho
Nice
😛
You can still do it using ordinary method
but 6 double integrals
Wanna do one of them for practice?
Yes
I have like
9 more problems left
For this section
16.7
I still gotta do 16.8 Stokes’ Theorem
I gotta graph it
$$0 \le x \le 3$$
$$-1 \le y \le 2$$
$$1 \le z \le 6$$
LUNA
just imagine it, don't graph
it's like a box in the middle (origin) of 3D space
length from x=0 to x=3
width from y=-1 to y=2
and height from z=1 to z=6
I will try, wait
i can't lol
just imagine a box
around the origin of 3D space
length from x=0 to x=3
width from y=-1 to y=2
and height from z=1 to z=6
let me graph it by hand
Something like this
it's okay, it's just to observe
what we doing
does not need to be exact
K
Let's do these 2 surfaces for example
The surface integral across S1
$$\iint_{S_{1}} \vec{F} \cdot \vec{dS_{1}}$$
LUNA
Let's start with F
$$\vec{F}=z , e^{xy} , \hat{i} -3z , e^{xy} , \hat{j} + xy , \hat{k}$$
LUNA
Do you think we can simplify F here?
Like do modifications to it
Only valid for the surface S1
All points in S1 have one thing in common, which is consant
Z=1 to 6
All points in S1 have one thing in common, which is consant
How
Isn’t it Y
y is varying, z is varying
That is constant
it's constant, 3, for all points in S1
Therefore, only within this integral, you can substitute x=3
instead of leaving it variable x
$$\vec{F_{1}}=z , e^{3y} , \hat{i} -3z , e^{3y} , \hat{j} + 3y , \hat{k}$$
LUNA
,rccw
Now take curl?
$$\iint_{S_{1}} \vec{F_{1}} \cdot \vec{dS_{1}}$$
LUNA
0 0 0?
you don't calculate it
it's given by
Since the normal vector is in direction of x
you use dSx
$$\vec{dS_{1}}=dy , dz , \hat{i}$$
LUNA
Did you digest it?
No
I think this is all new to you
I mean I don’t think my lecture notes has that
This is how you express differential surfaces
we're just evaluating the integral right
We simplified F
now, dS
He doesn’t have that anywhere
eeeeh, you should do it the way you guys do it then
this one is direct
substitute F, substitute dS
integrate
check with your classmates for example, how they did it
or consult your professor
mhmm
what can i say, this is the method I know
the direct way
but stick to how you guys did it
you must learn mine though!
even when you use the divergence theorem, you will need to express differential volume
stokes' theorem, you express both differential length and differential surface
no way to get around it
😛
Why is your teacher making it tedioussss
Well
I wish you luck!
I'll help you when it gets a little bit more advanced
I hate the way your teacher is doing it tbh
😆
do i send you some of the laws?
save them for later use
i have them written in latex already
Divergence theorem
Divergence computation
Stokes' theorem
Curl computation
How to express dl, dS, and dV
Save them for later use, you will need them
Yeah yeah, im just saying, have them, not use them
Someday you will encounter them
You will have the laws ready
Are you saying doing surface integrals isn't your passion??
chris i feel you
Okay
Soo my buddy texted me this
That one is for a later question about a cube (saw it in answer guild while checking my work) but what you do after finding the crossproduct is replace all the x, y and z parts of the intial F forumla with the intial S parenters given (in this case x= u+v y = u-v z=1+2u+v) and then multiply it by the crossproduct you got
@rigid gulch Has your question been resolved?
Closed by @rigid gulch
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
What have you tried so far?
Tried getting value of R in terms of other values and stuff
didnt really work
and the trig to find sides doesnt work either
yeah without knowing another angle I don't think trig functions are going to be much help
but what else could we do with a right triangle?
awesome, go for it
.close
Closed by @ripe wasp
Use .reopen if this was a mistake.
I didn't mean you had to close the channel lol
unless you already got it, in which case, nice job 👍
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
if anyone is around to help with this again i could use some 
Just repost it here
I know nobody is going to want to help with this but I was trying to work through some of the details in a paper by Knuth and couldn’t work out the step notated by the blue arrow https://media.discordapp.net/attachments/886483914410049556/1135765501797224671/IMG_2040.png
not really sure where the $\tau_j$ terms pop out from
rubixcyouber
from $$ \frac{\sqrt{2 \pi}}{e^m} \sum_{1 \le k \le m-1,;; j \ge 0} \frac{\sigma_j}{m^j} \frac{k^{k-1} e^{-k}}{k!} \left( 1 + k/m\right)^{\frac{1}{2} - j} \frac{1}{k+m-1}$$ , we can swap order of summation and sum j first to get something like
$$ \frac{\sqrt{2 \pi}}{e^m} \sum_{j \ge 0} \frac{1}{m^j} \sum_{k=1}^{m-1} \frac{k^{k-1} e^{-k} }{ {k! (k+m-1)}} \sigma_j (1 + k/m)^{1/2-j}$$
kinda looks like the result but not really - thats currently where im at
wow knuth really didn't like writing out his steps did he....
trying to expand it out
rubixcyouber
Yeah I got no ideas
If it makes you feel any better, you're definitely not missing anything obvious....
I think riemman was onto something earlier but not sure
If anyone has any suggestions I’m all ears
@distant adder Has your question been resolved?
@distant adder Has your question been resolved?
I don’t think will be answered 
@distant adder Has your question been resolved?
@distant adder Has your question been resolved?
BillyTheDancingKid
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
Hi, instead of trying to get the 3rd line from the 2nd you can do a reverse approach and try to get the 2nd one from the 3rd. I'll leave you the steps to follow:
Prove that the 3rd line is equal to
$$
\frac{2 \pi}{e^{m}} \sum_{k=1}^{m-1} \frac{k^{k-1} e^{-k}}{k!} \frac{\sqrt{k+m}}{(k+m-1)} \sum_{j=1}^{\infty} \frac{\tau_{j}}{(k+m)^{j}} (k+m-1)
$$
Just reducing terms and swapping the order of summation
After this check that
\begin{align*}
\sum_{j=1}^{\infty} \frac{\tau_{j}}{(k+m)^{j}} (k+m-1) &= \sum_{j=1}^{\infty} \frac{\tau_{j}}{(k+m)^{j-1}} - \frac{\tau_{j}}{(k+m)^{j}} \ &= \sum_{j=1}^{\infty} \tau_{j} (\frac{1}{(k+m)^{j-1}} - \frac{1}{(k+m)^{j}}) \ &= \tau_{1} - \sum_{j=2}^{\infty} \frac{\tau_{j}-\tau_{j-1}}{(k+m)^{j-1}}
\end{align*}
Finally use the definition of $\tau_{i}$ to obtain the 2nd line.
BillyTheDancingKid
Closed by @distant adder
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
why can't we 1) solve a^2 and sqrt(a) separately to begin with and 2) how can we perform the last simplification?
if we did a^2 and sqrt(a) separately they would be 2a and 1/2sqrt(a) , which gave me a v different answer
and i cannot understand exactly how the last simplification is performed. I know sqrt(a) = a^(1/2) . But I just see the variable removed from its exponent and magically there's a square root
It's a raise to the power 3/2
3/2 can be written as (1+2)/2
Which will give you
1/2 + 1
Powers of the same base add when they are mutiplied
It's kinda the reverse of the procedure of step 2 and step 3
the way i see it is we take a^(2/2) away from the right quotient and multiply it to the left, leaving us with a^(1/2)
is that right
and still can't see why we do the multiplication of powers. I know it's a rule and that we CAN do that, but I don't see why we HAVE to do that instead of solving them by themselves
Like the 1st one why we add powers during multiplication with same base??
a^2 * a^(1/2)
i know we CAN do 2+(1/2) giving a^(5/2)
but why do we HAVE to do that instead of solving them by themselves
So really don't have to add powers you can solve it without that as well
.
Just use the multiplication rule of derivatives
Lemme see ans should be same
Like we treat them as different functions a^2 and a^1/2
But I'll recommend this method only. It's way more simpler and efficient
so if we don't add powers during multiplication, we have to do derivation for these functions separately, and then it would be the same?
what is the multiplication rule of derivatives btw ? maybe i know but
nvm, found it
then i get $(a^2 * 1/(2sqrt(a)) + (2a * sqrt(a))$
marty
Now combine them using LCM
Either way you'll have to use these rules
For the first term you'll get (a^3/2)/2
i rearrange and get a^2 (which can be seen as a^4/2) multiplied with sqrt(a) (which can be seen as a^1/2). Thus I get a^(5/2)
and then i multiply a^5/2 with 1/2 and get 1/2a^5/2
thats my left term
what am i doing wrong
ah wait
it should be a^2 * 1/a^1/2
which is equal to 4/2 - 1/2
that gives a^3/2
divided by 2
but for the right term i get 2a^3/2
$(1/2a^(^3^/^2^)) + (2a^(^3^/^2^))$
marty
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
marty
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
So now you are on second last step??
marty
i did the terms through using the derivative mulitplication rule
and now added like terms
Nah that's now same
Here
a is in denominator
You can share the pic of ur work
It's kinda confusing
where the last term in my eyes could also be 1/2 * a^3/2 which would be 1/2a^3/2
is correct?
ohhhhhhhhhhhhhhhhh it's reverse power addition rule
a^3/2 = a^2/2 * a^1/2
Yeahh
which equals a * sqrt(a)
but now i learned how to do it from scratch, used the product rule for the first time lol, and got more experience with powers
yes its faster
1st method is more convenient
but now i learned more
Instead of product rule
Ohh good for ya!!!
No issues!!
wow
Btw where are you from?
Yeahh maths is magic in itself
i'm from norway but live in netherlands how about u
India
Same to you!!!
Sure!!
@keen nova Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how do i do B?
Did you solve a ?
?
it's asking for the domain
alr
mhm
the turning point is in the middle
yeah
what is x representing in your question?
the horizontal length
the horizontal coordinate?
0
OH
xD
Yeah
Closed by @mystic abyss
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
How to find the extremum of f(x)=x^2-6x+5
?
derive them
Do you know differentiation?
*differentiate it
yp
Given that it's a parabola, I suggest you find its vertex instead of using calculus
.close
Closed by @unkempt bison
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
whats the tips with these sorts of probability questions
these ones in particular are combinatorics questions in disguise tbh
really?
yes really
they can all be solved without pain by doing the (favorable outcomes)/(total outcomes) thing
btw i really dont like the wording of question 9
what part about 9
Where's the problem?
that too, but that isnt fully combinatrics
should i repeat myself as to the grievance i take with how question 9 is written
the permutation questions i have in my book have a similar wording
I don't understand what is not correct
I still don't understand what's wrong with it 😅
@gritty galleon don't sotrue me when i'm being 100% serious and genuine.
isnt sotrue supposed to mean 'so true'??
or is it sarcasm 
so to start simple with q7 what should be my approach
using "female" as a noun when you mean "woman" is creepy
can we please help OP
sorry i didnt know

find the number of ways to draw 2 balls from the bag -- for these purposes, all 9 balls count as distinct
then find the number of ways to draw 2 balls of the colors specified
Well, but females includes girls, women and so on, so I don't see why they should use women instead of females
I am worried about the other genders ...we forgot abt them
so 3 yellow, 4 pink, 2 black
if 2 balls are randomly chosen find probability of getting a yellow and black ball
a) with replacement.
so 9 balls in total but i think i need a little more help
so do i do 3/9 * 2/9 * 3?
where did the last 3 come from
from the three different colours
well ok let's forget that you didn't follow my instructions here but like
if you're gonna do 3/9 (for yellow) * 2/9 (for black)
then surely you will want to do that times 2 for the two orders in which you could get them
(BY vs YB)
is this product rule?
if you wanna call it that
may i ask why the order matters here
isnt getting a black yellow and yellow black the same thing
drawing a black then a yellow is a different event than drawing a yellow then a black
are we drawing them at the same time
no
we are drawing with replacement
this means we draw 1, record its color, put it back, and only then draw the second one
okay
so how about without replacement
well, if you want to go the non-combinatorial way then you still have to account for the different drawing orders
since you do still conceptualize your drawing as happening one by one, you just don't put the balls back
so P(B, then Y) = 2/9 * 3/8 and P(Y, then B) = 3/9 * 2/8
do i multiply by those 4?
hm
i dont understand why we're doing what we are doing
ok let's try this
if $A$ and $B$ are disjoint (mutually exclusive) events, then $$P(A \cup B) = P(A)+P(B).$$ agree or disagree?
Ann
agree
"we draw a black and a yellow in some order" = "we draw B, then Y" union "we draw Y, then B"
and the union is disjoint
agree or disagree?
im confused here so P(A) and P(B) can have multiple things happening? not just a single thing
P(A) and P(B) are not events but numbers. do not conflate an event with its probability!
also A and B are events. i am naming the events im talking about by their plain-english (but precise) descriptions.
said descriptions can, and routinely do, involve "multiple things happening".
okay
agree
i mean you don't need to agree to the same thing a second time...
wym what's next
i told you how to do problem 7, you said you got confused, now i am uncertain as to whether or not your confusion has been resolved
help
@tropic oxide how can i do this
get your own channel in #❓how-to-get-help
a deck of 100 tickets, 2 winners, 98 losers, we draw 4 w/o replacement
there are 100C4 ways to do that
er wait no ok
what is a c4
it's not 2 indistinguishable winners
it's a gold and silver again
100C4 means 100 choose 4
variously written as ${}_{100}C_4$ or ${}^{100}C_4$ or $\binom{100}{4}$
Ann
ill just resend it here
with these n choose k stuff i dont how how to really apply it to the questions
can we start with a
Ok, how would you start for a?
Closed by @nova snow
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Can someone please tell me why is this true if the sequence of (An) is increasing
The union sign with a dot on top means that the events are incompatible
the events are disjoint, you mean..?
Meaning the intersection of the two sets is the empty set
yes, disjoint
Yes
ok
Yes thank you
have you attempted writing out a proof of this equality?
Yes ,what I don’t understand is how a serie became a limit
there are no series or limits...
there are only indexed unions
$x \in \bigcup_{n \in \bN} A_n$ iff $(\exists n \in \bN)(x \in A_n)$
Ann
Yes but we can work with sequences,and series of sets the same as with ordinary ones
not really
Since the relation of intersection and union are relations of order
Really?
union and intersection are not even relations, they are operations.
the notion of 'limit' is somewhat... involved for sets.
union and intersection are like 100 times more elementary.
I see
I am sorry for my mistake
So what are the first and second sides of the equality
I mean I can understand the first one as a union of n sets but what about the second one
no, it's not a union of n sets, it's a union of infinitely many sets
as is the right-hand side
Alright it worked since I can form any An from the union of the other sets
Thanks for your help
.close
Closed by @old basalt
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
why
which step you don't understand?
Like you mean RHS of steps 2 and 3?
Closed by @turbid spoke
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Hi
I wanna ask why can system of linear equation can be represent by matrix
Closed by @carmine pilot
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Kind of confused whats going on here
the 3rd matrix there seems like it would be inconsistent
since i have 4x_2=3 and 6.5x_2=4
oh wait nvm
.close
Closed by @crude gale
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Let the matrix A ∈ R 3×3 have the eigenvalues 0, i and -i. Then the linear system y'(x)= Ay(x) is:
stable and asymptotically stable
stable and not asymptotically stable
unstable and asymptotically stable
unstable and not asymptotically stable
I choose stable and not asymptotically stable because we only have 0 as a real eigenvalue. Am I right?
@spring owl Has your question been resolved?
<@&286206848099549185>
@spring owl Has your question been resolved?
gotta wait for the smart people
lmao
wow this hits the nail on the head, thank you!
.close
Closed by @spring owl
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
yes
Closed by @spring coyote
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
I’m tryna understand the question of my book. It says determine the period for the following rational number
What is the period
it would be awesome if you could show us the rational number in question
usually period is a term for trig functions
It shows diffrent numbers
Like 2/3
-63/99
16/7
send a picture of the question please
2
Its on swedish
tl?
translate
I just translated
I looked up period of rational numbers and it said it is the repeating digits of the rational number
of its decimal expansion
I dont have a great calculator
so 2/3 I assume it's period is something along the lines of 66
No on my book it says 6
,w compute 63/99
63
Here book Says its 63
yeah
,w compute 16/7

2 doesn't repeat
Thank you
Thank you
Closed by @lament kelp
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Hmmm trying to find the inverse laplace transform of [
\cmap {\mathcal L}{\map f t} = \map \log{\f{s^2+1}{s(s+1)}}
]
It's kind of weird though because I'm unsure on how to deal with that log
I'm not sure, but is it like with limits where you can bring it outside since it's continuous or smth?
log(a/b)=?
Yes loga - logb but you still have to deal with the log
Do you take e^log or something
Yes
Austin
Well definition of Laplace here we go
Is it in a table you have
@crimson sedge Has your question been resolved?
No truth be told I am familiar with all of those except 17-19
Any link for me to understand them?
Just follows from integration by parts
https://math.libretexts.org/Bookshelves/Differential_Equations/Differential_Equations_for_Engineers_(Lebl)/6%3A_The_Laplace_Transform/6.2%3A_Transforms_of_derivatives_and_ODEs
@crimson sedge Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Im not sure how to do this?
Do we have to re parameterize t in terms of something else?
yeah, can you write out the equation?
yup, so what's the curl of F?
awesome and then how can we parameterize the disc?
that im am not sur
okay so we have a parameterization of the circle already
we need to figure out how to turn it to a disc
maybe in terms of cylindrical or spherical coordinates?
hmmmm well
first let's start with this
what are the parameterizations of the unit circle and unit disc in 2d?
$(r\cos\theta, r\sin\theta)$
KN
yup
so the circle comes from setting r=1
and the disc comes from letting r range between 0 to 1
right?
KN
idt that is correct.
almost
so like
in 2D we went from (cos t, sin t) to (r cos t, r sin t)
now we have (cos t, sin t, sin t)
how should we "fill in the circle" to make a disc?
Based on how we did that in 2d, it should be (rcos t, rsin t, rsin t)?
yes!
no problem, do you know how to do the surface integral from there?
Closed by @crude scroll
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
actually
yes!
r=0 corresponds to the center
and r=1 corresponds to the outer ellipse
no problem!
.close
Closed by @crude scroll
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Is there more to the answer
Which part exactly is confusing
What's below the last line
Can you show it anyway
How annoying
Yea they used demorgans law for intersection of two compliment sets
Did you learn demorgans laws yet
yep
so there is more to the answer?
like doesnt wut he just proved just show that x is subset of AUB(complements) so then its also of AnB(complements) since its not in AuB?
Yeah I think the answer given there is just incomplete
@sharp viper Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how can they determine this?
here's the problem
this is a known property of normal RVs
Sums and linear combinations of jointly normal random variables, proofs, exercises.
see example one
it also contains a proof
oh ok I'll look at that thanks
it's a minus
yeah Ik
well generally $var [aX+bY] = a^2 var X + b^2 var Y$
I meant in the question
what
jan Niku
yes, but i think its better you just use the linear combo form i posted
Closed by @lethal bison
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Can someone please explain me the red underlined part?
I don't have a slick way of seeing it, but one thing to note is that if t > s then t/(1-t) > s/(1-s), so you can check the two cases t > s and t <= s.
I see. That I realised, but I don't understand how they came up with these terms?
If t < s, then E(BtBs) = (1-t)(1-s)t/(1-t) = t(1-s) = min(t,s)(1-max(t,s))
If t > s, then E(BtBs) = (1-t)(1-s)s/(1-s) = s(1-t) = min(t,s)(1-max(t,s))
Many Thanks!
.close
Closed by @ocean wolf
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
if my mom say my dad not at home to get milk yesterday, when will he get the milk today? and how many milk he have?
exactly e^(pi*i)
i know it equals -1 but where he stole it from? need the answer for that
from somewhere he wants to keep secret from you ofc
@soft wagon Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how do i solve this? it's a calculus concept that i haven't really learned much about
how would i do that?
well what's the inverse of log base 10?
is it just ten?
sorry im not good at this
6^x?
exactly
now look at the problem
imagine that everything inside log base 6 is equal to a variable u
giving you log6(u)=0
try solving for u
okay so u = 1
alright now substitute u for whatever was in log base 6
yep
alright, ty
np!
wait also sorry one other thing
for this one, is it the same method or do i start from like the inside?
you should start from the inside
okay, ty
wait would the one on the inside be equal to x too or a different number?
oh wait would i just set it equal to a different variable
you can calculate from the inside
log5(25) is 2
log2(2) is 1
well i got to 1=3^x, im not sure how to solve that
@crimson sedge Has your question been resolved?
Closed by @signal hollow
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
i can use a calculator on this, but im not sure how to interpret the given function because of the subscript 0 and the k next to the t. how should i go about solving this?
The k is constant subscript is no. Of bacteria at t=0
do i need to know the value of k?
@crimson sedge Has your question been resolved?
never mind
did you end up figuring it out
not really
no one showed up but i asked this question somewhere else
i have another question though
but its unrelated to this problem
does anyone know what it means when it says to say what values of theta does it intersect the pole? because isn't the pole the center of the polar graph? im not sure how it can have an angle measure
Math sucks
a 0 subscript typically indicates a starting condition. To find the function, start by setting t=0. When t=0 then eᵏᵗ = 1, so n = n₀ (we are given the start amount in the problem).
then solve for k with the value you have for n₀, and with the given information (n = 1200 when t = 1)
for certain values of θ the function will return r = 0. remember that multiple different polar coordinates can point to the same spot
oh okay, thank you
also do you know what it means when it says to tell the values of theta that make it so the graph is drawn only once
for some of the graphs once you get a high enough value of θ it will go over the exact same points over again (because sin and cos are periodic functions), so you want to find a range for θ where it draws the whole function without going back over itself
do you know how i would figure that out?
probably easiest to work it out from the graph
oh okay
so would a circle just have the range of 0 to 2pi
yes
okay - and would that be for any circle or just a circle that isn't touching the pole
it would be true for the usual form of a circle in polar coordinates, which is a constant radius (e.g. problem 60)
so it wouldn't be true for 61?
it wouldn't, no
is there another way to figure it out for that type of problem then? or do i just need to look at what polar coordinate lines the graph touches?
it can be difficult to tell purely from where the graph touches since any given angle can put you in one of 2 quadrants. if the graphing software you use supports it, try changing the angles used as inputs until you find the smallest range that still has a complete graph
i can't use any technology on these types of problems though
for this specific assginment
in that case i'd start drawing until it seems like it "completes a loop". that may be before or after you reach 2π
i drew out the graph and it's just a circle thats on the right side of the y axis
while you're graphing, try to keep track of which angles you're going through. in that case, it started in the first quadrant, then went to 0 at θ=π/2 and completed the circle at θ=π
@crimson sedge Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
is this a good enough tesselation?
Yeah
@hot python Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
/
Idk what to start
generally in statistics when we look at a sample we're trying to use the data to find a statistic (calculated from the data in the sample) to estimate a parameter (calculated from the population, difficult to measure).
Parameter?
Idk, but if i answer. Ill answer B, but the answer A and C i dont understand
just because the mean number of dramas was 15 doesn't mean many people watched exactly that number. It may be that none of them watched exactly 15 dramas.
remember we're talking about the mean, or average
Ya
But like
It also say like margin of error of 3
Thats the part i felt most uncomfortable with
basically we couldn't interview every single student. but we want to have some idea of what the average is for every student anyway.


