#help-27
1 messages · Page 369 of 1
oops guys
the calculator didnt show it anymore
i think i pressed smth wrongly again several times
again, reproduce it
sorry sorry sorry
wait whats reproduce
do the same calculation again but be careful to do it with the exact same steps as the first time
2.3 is correct
Closed by @sour spire
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 you get BD? Is there some sort of theory I'm missing out on here? I'm in 12th grade & this is a bit embarrasing that I'm stuck on something like this lol. Shouldn't have slacked off in 9th grade...
I went & solved for BC using a^2 + b^2 = c^2, but I can't seem to figure out how to get BD. The explanation says some angle similarity theory but I have no idea what that is & would appreciate some more detailed explananation!
@opal mantle Has your question been resolved?
have you drawn a pic/sketch
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 solve this ?
do I need to substitute values of n and just try random hit and trials?
not really
Idts it seems like a recursion based problem
i found few values like $a_2=1 , a_3=4 , a_4=11 , a_5=26$
Prathmesh
u can rewrite the recurrence to note something about the nature of the sequence
wdym by recurrence?
This sort of thing, where new terms are defined by old terms, is called a recurrence
ohh
It can be solved. Have you been taught how to solve it?
Have you searched up any online resources? Khan academy can be quite useful.
if possible, you dont want to do that here, since the solutions might be complicated exponentials
there maybe some pattern
can you help if you noticed it?
,, a_{25} (a_{23} - 2a_{22}) - 2a_{24} (a_{23} - 2a_{22}) = (a_{25} - 2a_{24}) (a_{23} - 2a_{22})
mmmm7
so you want to learn something about a_n - 2a_{n - 1}
rewrite that to accomodate for that
$a_{n+2} -2a_{n+1} - 1 = a_{n+1} - 2a_n$
Prathmesh
yep
so you can imagine defining a sequence like t_n = a_{n + 1} - 2a_{n}
to then have t_{n + 1} - 1 = t_n
looking back here, your task is then to find t_{24} and t_{23}
i don't understand
which part?
$\underbrace{a_{n+2} -2a_{n+1}}{t{n +1}} - 1 = \underbrace{a_{n+1} - 2a_n}_{t_n}$
by definition^
for convenience sake we define a new sequence t_n and we note that the difference between consecutive terms in the sequence is 1
won't it be t_n+1 in the lhs
yep typo
^
ohh
mmmm7
that's it
i mean you're tasked with finding t_{24} and t_{23}
can you find any t_i for some i from given info
if you can do that then you can find t_{24} or t_{23}
not for any i but I can find few particular values with the given info
like ik this so i can plug in and calculate few values
you have a_0, a_1, and possibly some more values
surely you can find t_0 or something
yea

btw how did you think all this up ?
well since this looks like a jee problem or smth
you're certainly not supposed to "solve" the recurrence
so factorizing and hoping that there's some pattern dictating a_n - 2a_[n - 1} was the next natural step
damnnnnn genius
far from it 😭
still that was so slay
💅
Closed by @fervent helm
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
well, you already know that its an arc of a circle
and its centered at B, coz thats given
so, all that remains is to find the angle ABC to determine how much of a circle that arc forms
then bcs is 90 its a quarter?
i dont understand how the other unshaded region is a quarter of a circle
And importantly, they are talking about the semicircle + shaded region,
yes, coz whole circle is 360 deg, 90 is quarter of that
type .close
Closed by @vivid summit
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Hey, do i write 3sinx³ or 3x², the last line where i just wrote 3
I think this will help you resolve your question.
@dusty fox 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
No, it doesn't. Just explain pls 🙏
I thought u put the constant at the front and then write it as is
But the answer had -3x² -not 3x³
That is correct.
Which part are you confused about?
You wrote: $y' = cos x^3 \cdot 2 sin x^5 \cdot cos x^5 \cdot 5x^4 - sin x^3 \cdot 3x^2 \cdot sin^2 x^5$
Erebus
Hold on
$y' = 10 : cos x^3 , sin x^5 ,cos x^5 , x^4 - sin x^3 \cdot 3x^2 \cdot sin^2 x^5$
Erebus
-3sinx³•x²•sin²x⁵ ?
YES
Hih???
That's correct.
Really
The last part.
I put the u then v
The answer I'm looking at had v then u
$- sin x^3 \cdot 3x^2 \cdot sin^2 x^5 = - 3 :sin x^3 , x^2 , sin^2 x^5$
So i did u•v' + u'•v
Erebus
They did v'•u+u'•v
Could it be because of that?
Oh
It's the same.
Ok but they had -3sinx² is that correct too?
A and B, B and A, the same
The last part should include that part.
But it should not be the entire last part.
I didn't include that part...is it still correct?
I didn't include that part...is it still correct?
Nope
It should contain all
But i wrote what u wrote
Then, you're correct.
I mean, from this conversation, your idea is correct and your answer is also correct.
Let me write it out fully
Ok but -3x² is a diff value then none of us wrote
$y' = 10 : cos x^3 , sin x^5 ,cos x^5 , x^4 - 3 :sin x^3 , x^2 , sin^2 x^5$
Erebus
What do you mean by that?
The postioning of the terms?
You could write $- 3 :sin x^3 , x^2 , sin^2 x^5$ as $- 3 : x^2 , sin x^3 , sin^2 x^5$ or $- 3 : x^2 , sin^2 x^5 , sin x^3$
Erebus
what the hell is going on here
It just depends on your preference.
I don't know.
I'm just hitting all the dialogue options for now.
we have $\dv{}{x} \left(\cos(x^3)\sin^2(x^5)\right)$, yeah?
lemme rewrite that
ok.
Περσυ
@pure flower
yeah idk what the fuck they did
that derivative is so wrong
ok first term is right sure
whats the second term
3
Which part was wrong?
..whats the 3.
This part?
weird
...do you mean prefered order
like it super doesnt matter
but clean order is $-3\sin(x^3)\sin^2(x^5)x^3$
Περσυ
or maybe $-3 x^3 \sin(x^3)\sin^2(x^5)$
Περσυ
@dusty fox 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Hey, this is the proof of finding coordinates of a excenter , Im confused at the highlighted part i dont understand how that is true can anyone please help prove the highlighted point
@charred turret Has your question been resolved?
@charred turret Has your question been resolved?
Note that $BI_1$ is the external angle bisector at $B$. So, by the exterior angle bisector theorem,
$$\frac{AI_1}{I_1 L}=\frac{AB}{BL}=\frac{c}{\frac{ac}{b+c}}=\frac{b+c}{a}.$$
Civil Service Pigeon
You can also do this with barycentric coordinates if you want to
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 would I go about proving this ?
So say I assume N is a normal subgroup of G then show that gng-1 is in N
But surely that’s just obvious
Cause of the definition of the normal subgroup
which is gNg^-1 = {gng^-1 such that g in G and n in N}
Then the other way, if gng-1 is in N then this just implies that it’s a property of a normal subgroup
Idk what I’m missing 😭
What is the definition of normal subgroup that was given in your class? Was it a subgroup N such that gN = Ng, for all g in G?
If so, you are right, there is almost nothing to do for your exercise, but your writing above is a bit inaccurate
I was given gng-1 one
Not the gN = Ng
Where would u say it’s flawed?
Here for example, you claim this is the definition of N just before
And you use N in the definition itself
Well I mean is that not it, like a normal subgroup contains its conjugates
Idk how else to prove this for th exercise
Can you show the definition of a normal subgroup exactly as it is stated? Assuming you are doing this for a course
Yea sure
Ok, can you see the difference with the definition and the exercise?
No, the definition tells you $N$ is a normal subgroup of $G$ if (and only if) $gNg^{-1} = N$ for all $g \in G$. \
The exercise, however, asks you to show that $N$ is a normal subgroup of $G$ if and only if $gNg^{-1} \subseteq N$, for all $g \in G$.
all matrices are invertible
In other words, for all g in G, it is sufficient to only check for the inclusion of gNg^{-1} into N, to conclude that N is a normal subgroup.
Well, this is what the exercise is asking you to prove.
Oh I see
OHHH bruh
Nah that works 😭
I think I was overthinking it
lol tysm
.close
Closed by @pastel rose
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 not sure if this is so suitable for this channel, but I am to write up a proof of any geometry theorem using vectors. any suggestions?
@crude anvil Has your question been resolved?
cosine law is a good place to start
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 determine all the continous function f:D->R where f(2x)=f(3x) for every real x
i rewrote that as f(x) = f( (3/2)^n * x) for every n natural
hint: take a limit
for n or for x
what do you think
limit of n, not x
this is kind of spoiling but you are trying to show that f(x) = f(0) for all x, thus the solutions are the constant functions
how would you do that with a limit?
oh
i understand
i rewrite
it as
f(x) = f((2/3)^n * x
.closed
done it thanks
.close
Closed by @prime vigil
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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, can someone help me with this?
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
3
Show your work, and if possible, explain where you are stuck.
it's not normal trust me
1
wdym
if i remember correctly, 1 appears more than other digits as you go along
@weak lichen Has your question been resolved?
@weak lichen Has your question been resolved?
Isn't base 10 just the base we use? 0-9???
So it's not normal
And for the second part.
As you go farther and faster.
Consider 11111 and so on.
You will see that the numbers 1 and 2 will appear more frequently than any other number.
what level of math are you studying? I've never been taught to do this yet this seems elementary but tricky
So no. They don't have a limiting frequency of 1/10
Prove it bro
Best I could come up with is that if you take an interval from 1000-1999. Then all numbers between that interval can be represented as a sum of 1000 + k. if 1 appears only 1/10 of the time. It means that only 1/10 of the numbers starts with 1000. Which implies that 9/10 of the numbers have a number greater than 1999. Which means that between the interval 1000-1999. There's a number, such that 2000 + k = 1000 + k. Which would imply that 2000 = 1000, Which is a contradiction.
(This is the best I could come up with, I know it work for all number 1-9)
Can't come up with anything better
😭🙏
But wait, would it work if you take this approach on every place?
Oh my fuckin god.
Not the leading digit.
AAAAAAAAAAAAAAAAAAAAAAAAA
I mean, i don't feel like trying it
But i'd start by considering the frequency of the digits 0-9 for n-digit numbers
What about uhh.
What if you start by trying to like. Make a pattern or somethin.
Like. 9 appear 100 times through 1-1000
Not sure what kind of pattern you're thinking of making.
Idek myself. 😭
It appears more than that
I mean it's just an exercise in counting
1st year
Yeah fuu
You have 100 occurrences for 900-999, sure, but there's at least 101-th appearance in, say, 9 itself
That's why restricting to digits is probably the right move
I don't understand your question
Aaaaaaaaaaa
I think the number of nines should be that.
9.11?
I haven't done any calculation but I'm almost 100% sure that's not it
Yesh
How many 9 digits appear in two digit numbers?
It's easy: we can start with the 90's
It appears eleven times.
Then you have seven other starting digits, in which 9 appears once, and the ones, where 9 appears once
So yeah, 19.
there's a recursion
There ya go.
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Theoretically, what would the result be if this did work? Does this even make sense?
(such that i is the square root of -1)
I am only more confused
but like theoretically wouldn't it just be 16+30i, because the integral from a to b on 2x is just b²-a² i think
but also how does this extend to other functions
no, because complex numbers lie on a plane, unlike real numbers
think about what it means to go from 0 to 5+3i on the complex plane
versus going from 0 to 5 on the real number line, for instance
still travelling in a line tho right
well yeah the answer is right in this case, but you cant always just integrate like that
it doesnt generalize
if its path independent, you can essentially integrate normally
so for f(x) = x^2 it works as well
so technically it works for almost all functions you would want to integrate, but it doesnt apply to any function
and its very sloppy in general, because it doesnt give you the proper intuition of what complex integration actually means
@severe anvil Has your question been resolved?
if you're curious, i would reccomend you looking at the link riemann posted above
i think where we're confused is that im thinking of integrate this function from 0 to x which works normally when x is a real number, so why wouldn't that work if x is complex
it does work (so long as the function is analytic everywhere)
You should also read about line integrals first
yes
@severe anvil integration for functions like this works because the integral is path independent, so you can choose the straight line path from 0 to z, and integrate normally
Closed by @severe anvil
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 E
What have you tried to solve it
@echo dragon Has your question been resolved?
Nothing
You know what sin(pi/2) is?
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 property/axiom should I cite to justify multiplying by (a - 1) so that the left hand side is divided by (a - 1)?
Closed by @scenic 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 should be the limits?
the limits of what?
the triple integral, using cylindrical cordinates
oh
surely you don't have to triple integral, im not super well-versed in calculus but it looks as if thats excessive
my intuition tells me to shuffle the two non-trivial equations to look nicer
i dont understand?
should it be: z: 0 to r^2/4; r:0 to 8sin(theta) and theta: -pi/2 to pi/2?
no
Mb
well the answwer i get from the limits is 96pi but the answer given is 64/3 pi
96 pi is cuz you converted it into the sin integral I presume?
theta would be from 0 to pi, no?
what is sin integral?
what limits did you get?
both still give the same answer
no they won't
for this integral sin must be positive cuz r≥0
i dont understand?
lemme explain
since r = 8sintheta
you can say that this is a circle of radius 4 centered at 0,4
and since r is a distance
hey 👋
and cannot be negative
r≥0
because by definition r is equal to the root of x2+y2
ohk, got it
yes
that's why -pi/2 gives an incorrect answer
try 0 to pi and you'll get the right answer
wait a min, i will try
and substitute u = r2
mkay I calculated the integrals
in cartesian and cylindrical both give the answer to be 96 pi, I believe the book is wrong
The answer given is certainly wrong or I'm missing sumn
yeah i think so too
mkay
.close
Closed by @sly oyster
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Solve the following equations by using the given substitution. Leave your answers in exact form.
Q1. x^2 + 2x - 2root(x^2+2x) = 3. Let u = rootx^2+2x
Q2. x^2 + x + 12/x^2+x = 8. Let u = x^2+x
show ur work
main focus currently is q1 right now
working is up to (for q1
u^2 - 2u - 3 = 0
skipping a step
u = 3, -1
LordFelix
u got the equation
whats the doubt then
okay, so you have u
solve for x
no i'm kinda confused let me type my workkng out
Case 1: $3 = \sqrt{x^2+2x}$
LordFelix
yep
you need to define u >= 0
no you dont
no u just need to square so it doesn't matter
k
what he DOES need to do is check all the solutions of x when he gets them
nope i'm really confused right now, skipping a few steps i'm up to x^2 + 2x - 9 = 0
that's correct (for case 1)
can you solve that?
do i use the formula x=-b rootb^2-4ac/2a ?
well, it is a quadratic, right?
Use whatever method you like/have been taught for quadratic equations
okay so would the answer be -1 plus minus root10?
i'm trying to figure out if i went wrong or not bc my friend is asleep and her answer is not simular
that sounds correct for case 1
okay thank you
now you need to solve case 2
and for case two i got -2 plusminus root8 over 2
Case 2: $-1 = \sqrt{x^2+2x}$
LordFelix
and now you need to check all those 4 solutions
you have to check that, first off, the original equality holds for those values, and second, that x^2+2x is positive (assuming you're in R)
Pay attention to the signs here. Is this even solvable 😉 ? @blazing hollow
u = -1
he's not asking that
Forget about u, also because you've already found the values of u
can the sqrt of a number be negative in R?
i'm so confused rn
in the real numbers
i dont remember the latex code for it
\mathbb{R}
huh
LordFelix
there we go
i'm so confused can you elaborate on how -1 = rootx^2 + 2x is unsolvable
In other words, can you solve $\sqrt{x} = -1$ ?
this isn't
Alberto Z.
precisely
There you go
it doesnt matter what is inside the root
but how is it the same
so -1 equaling to
OHHHH
thank you very much
so both values obtained from u= -1 are not gonna hold on the original equation
that makes more sense
but you still need to check the values that you obtained from u=3
are we not taking complex numbers
so u can only be -1 plus or minut root 10?
I don't think so at all
those CAN be solutions, but you do not KNOW they are until you check them in the original equation
okay thanks
?
the variable is x, not z. I'd assume we arent
Alright, that confirms it 😅 @thorny bloom
currently in y10 so sorry
Don't worry
y10 tutor math at least
that tells us very little, we dont know your school system
australian
oh no like in quadratic equations the answer can be in form of i without z
yeah we aren't using i, i tried googling a few of my questions that came up with the answer 2i or something similar but i figured it was unsolvable -- idt im up to that level
thank you guys
you should get to that level in 1 or 2 years probably, but just not yet
what i tell my students is that they should keep in mind that those exist, but that we're not gonna use them yet
kill me now
because knowing they exist is helpful for other things, like factoring polynomials
so when they get a result where they cant continue, it's because one of those appeared, and they dont need to continue
and not because they got it wrong
ohhh okay
that way some theorems are easier for them to understand as well
Closed by @blazing 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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, would someone be able to explain how to sketch sinusoidal waves??
you need two things:
- the range, or minimum and maximum
- the starting state
how do you find those??
Find derivative
Or just plug max and min value of sin and cosx
dont find derivative 💀
do you know the min and max of sin x?
is it 2?
is what 2?
i just want sin(x) lol
not necesary at all
@mellow nest Has your question been resolved?
Closed by @mellow nest
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Hello
yo, have a query?
No
This channel is only for on-topic discussion. Please take casual conversation to #discussion or #chill.
Ok 👌
type .close
.close
Closed by @midnight echo
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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’m so confused here
These definitions are too much 😭
It’s just saying all the valid outcomes which have a probability of being greater then 0
So for the question
How can I even think abt it
😭
What is an outcome that has zero probability?
Well a fish that’s not tagged?
According to X
It could very well happen that some of the fish are not tagged, so the probability of throes outcomes are nonzero and in fact are apart of the support
And the probability of a fish being tagged is also non zero
Oh wait
Unless u get all 10 fish which aren’t tagged
Is that 0?
Nah no that wouldn’t be
That’s still in the support
Surely what ever type of fish you get, the chance of that being in the support is 100%
Wait uh
I think I read ur RV wrong
RV?
X
What’s rvx?
Random variable = RV
Ohh
Okay outcomes in this case are numbers
Support of X just means the different scenarios of X with non-zero prob.
Yea so surely that’s just all possible outcomes no?
So can you come up with an outcome (a number of fishes) that have probability zero?
Cause you either get a fish with a tag or a fish without
There’s only 10 cases here
So a probability of 0 means no tagged fish?
And that’s the support?
You’ve intuitively already answered the question in some sense
Is it possible for X = 11?
So what’s the support?
Yes (integers and >= 0)
Ah I have to state integers cause of them being while fish
Would I I write that formally?
Just the support so X = {0,1,2,3,4,5,6,7,8,9,10} ?
It’s all the x such that P(X = x) > 0
Well its an outcome which have probability of more than 0 to occur
Yes
Oh so this is fine
This was already in some sense clear to you before even thinking about the problem I bet
Yes
Yea its just this way of formalising which I’m trying to understand in some sense
Mhm
I’d say the key here was to recognise what the outcomes in the first place looked like
So give each outcome a probability then
Not fishes but numbers
Oh alright
When we say probability mass function what do we actually mean
Is it like, in this case for each possible number of tagged fish x, what is the probability that exactly x tagged fish appear in the sample of 10?
And the probabilities of each of them summed is 1
Hm idk if that even makes sense
How would I use ur idea of thinking of them in terms of number rather than tagged fish as
@pastel rose 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Channel closed due to the original message being deleted.
If you did not intend to do this, please open a new help channel,
as this action is irreversible, and this channel may abruptly lock.
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Given an almost exact equation here, is it legal to like put the dy and dx back to dy/dx? aka y’
Ik we can change y’ to dy/dx and separate but someone told me if we started with dy dx we cant glue it back to y’ idk if it’s true
depends
On?
its legal. the issue is it doesnt seem separable
well it depends if the function doesnt change like people in physics do du/dx*dx/dt= du/dt is a lil invalid but moreover in variable separable method (which is the method used to solve the given question) it is allowed
which is one of the method that CAN be used*
Yeah I’m giving an example that’s it
I would just like to know if legal
its legal
Ah ok ok
Ty
Okay so in every case where you know dy/dx are linked it’s legal right?
if u can see that y and x terms can be separated do for it
to solve a differential equation it is best to form dy/dx first
so yes it is legal pretty much
in fact the form with dx and dy on separate sides is a sort of abuse of notation (until you rigorously learn differential forms later) and is just meant to be a mnemonic for the form with dy/dx on one side
true
@lament schooner Has your question been resolved?
Ok thanks guys
Closed by @lament schooner
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Hello I need help
Can someone pls look over this work and tell me if this is correct
If not tell me what I did wrong and correct it for me
Thxxx
Any body
could have been done easier by checking that
2 - sqrt(5) = - (sqrt(5) - 2).
Multiply numerator and denominator of 2nd term by (-1)
In original q
2 -root5 = (root5 -2).-1
Where in the picture
at the start
Where should I change it
u would have to change the whole proccess shlawg
Im good
yeah
1st step
Do I just have to change that
no
Will I still end up with the same answer
no
u went with the most complicated way lmao
u prob got something wrong in the middle of all that stuff
The answer he got is incorrect right?
@surreal orchid Has your question been resolved?
sqrt(5) - 2sqrt(5) is not 3sqrt(5)
1-2 = -1 in my book!
thats backtracking from the result btw, im not sure if you've made any other mistakes
@surreal orchid .
Op went to sleep
as in you know that they went to sleep or is that a metaphor
Assumption
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 working on Linear Algebra Done Right 4th edition question 6.A.19:
Given that this is meant to be true for any basis, my intuition is to phrase this question in terms of operations on T and basis vectors. However, I am stuck. Is this approach wrong, or could I have a hint at how to phrase it?
Help. FAST, why in 3. Am i getting the line in wrong direction?
f(x) = 2-sqrt(1-x)
I did the table…
Your intuition is correct, but the question is much easier to solve maybe if you think about the coordinate vectors F instead of thinking about the T operator.
@fair fjord Has your question been resolved?
I'm not sure that helps - I've been playing around with 2x2 real matrices trying to get matrix multiplication w/ a vector to look anything like a sum of squared entries, and I think I'm missing something
Yes, your steps are absolutely correct. Have you thought about trying the Couchy Schwartz inequality next?
I'm thinking I need to end up there eventually, but in order for that to get something relevant I need vectors v, w w/ one of <v, w>, ||v||, ||w|| looking like something in the question
which is where Im stuck
thats why I said this actually, in this way we can get what we needed as vectors.
ok so I get that the original sum is the same as $$ \sum_{i=1}^{n} || T\vec{v}_i ||$$ - is this what you mean
Plaisk
That's right
OH - so with some eigenvector v of norm 1, we have $<Tv, Tv> = |\lambda|^2$ and these terms are all in the right sum somewhere if we break v up to basis vectors?
Plaisk
nah that doesnt work nvm
When you decompose $v$ into basis vectors ($v = x_1 v_1 + \dots + x_n v_n$). We need to prove that the sum of the squared matrix entries on the right is greater than or equal to your $|\lambda|^2$. Then Cauchy-Schwarz inequality to get rid of those $x_k$ coefficients and establish the $\le$ sign.
ShaddowDagger
Since you've already reached this point I think you can handle the rest from here
prob eventually! thanks!
Im glad I could help 
@fair fjord Has your question been resolved?
Closed by @fair fjord
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
uhh my brain is throbbing cause my friend asked me this question
and he has to describe the transformation in words
i assume that how each component of g(x) transforms f(x), such as how "-3" transforms f(x)
the thing that im going insane about is the f(x+1)^2
What does the ^2 notation mean in this context? f(x+1)*f(x+1)?
i'm going to assume that the notation $f(x)^2$ means $f(x)\times f(x)$
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
in my opinion there's really no other way to word the transformation f(x)^2 without just saying it turns the parabolic graph into a quartic-shaped graph
yeah uhh apparently his answer key says otherwise... its looking at it without the ^2
yeah uhh
is it just a typo
so it's 2f(x+1)-3?
without ^2 it looks more reasonable
uhh apparently thats what the answer suggests...
but he is even more confused about this...
apparently its x cannot be equal to -1..
one question at a time please
ah mb
so i assume g(x) here means 2f(x + 1) - 3
yeah
think about what each constant does here, they must be transforming the graph in a way
what does multiplying by 2 mean? what does adding 1 to the variable x mean? what does subtracting 3 from the whole function mean?
if it helps, play around in desmos
i know what it actually is without the ^2, was kinda just puzzled by the notation..
vertically stretched by a factor of 2 about the x axis, horizontally translating it 1 unit left and vertically translating it 3 units down
yup that's the way
.close
Closed by @slate kite
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
would it be 4050 instead of 4900 after optimization because it cannot be a square?
because the barn takes a side
that's correct, cause if the area was 4900, you would need 70 + 70 + 70 + 70
but then 100 metres would be longer than one of the sides
I think you might need to check 4500 actually
@formal wraith 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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
Yes
Can you briefly explain the concept of unit circle?
I got to csc 1/sqr5 over 3 but I don’t know where to go from there
And after that, try to find the value of k based on the explanation
oh wow, lemme check
reminder: $cos(\theta) = \frac{\text{adjacent side}}{\text{hipotenuse}} = \frac{2}{3}$
Tales78945
call "adjacent side" as "a" and "hipotenuse" as "h" for better notation 🙂
Assuming your calculation is all right, that’s the answer, no?
They’re asking csc theta
It’s reciprocal on answer key
3/ sqr5
Could you show your work?
If u can decipher
,rccw
This looks correct to me, what is the problem?
I got $\frac{1}{\sqrt{(\frac{3}{2})^2 -1}}$.
@echo dragon did you too?
Tales78945
Okay for A I got 1/sqr5 over 3
Do I need to simplify that?
And for B I got 1 over -3/5
But the answer on the answer key is -5/3
$\frac{\frac{1}{\sqrt5}}{3}$?
VerifiedCrank
Isn’t it 1
Which one you on?
@echo dragon 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
Closed due to timeout
Use .reopen if this was a mistake.
.reopen
✅ Original question: #help-27 message
∀B,C ∀S,T: Functor(S) ∧ Functor(T) ∧ B, C are groups →
(∃η: NatTrans(η,S,T) ↔ ∃h∈C ∀g∈B, T(g) = h·S(g)·h⁻¹)
-h->
<-h⁻¹-
g-S->
B--S-->C
| |
v v
B--T-->C
g--S-->h
g--T-->h
trying tto build the diagram and figuring out what this pattern is
g = h ∘ f ∘ h⁻¹
this is equal g ∘ h = h ∘ f ?
then this is imilar to the pattern of topological conjugacy
magic:
g ∘ h = (h ∘ f ∘ h⁻¹) ∘ h = h ∘ f ∘ (h⁻¹ ∘ h) = h ∘ f ∘ id = h ∘ f
* ──S(g)──> *
| |
η* η*
v v
* ──T(g)──> *
η* ∘ S(g) = T(g) ∘ η*
η* = h ∈ C
T(g) = h · S(g) · h⁻¹
* ──S(g)──> *
| |
h h
v v
* ──T(g)──> *
* ──S(g)──> *
| ^
h h⁻¹
v |
* ──T(g)──> *
∃ h ∀ g seems like local-global pattern!
h is maybe something global to S and T,
a natural transformation connecting them
∃ h ∈ C s.t. ∀ g ∈ B = global map
η: S → T = global structure map
this seems very similar to how functor is global to arrows
.close
Closed by @fierce matrix
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
My friend had a question that baffled me.
Suppose we have f(x)=x^2 maped from R to R, can you change it's codomain to make the function injective?
From what we learned in the lessons, in order to make a function injective you need to limit its domain and not codomain.
But my friend suggests limiting the codomain to y<0 or even y<=0, and in both cases the function f(x) seemingly follows the definition of an injective function.
Is my friend correct?
you can limit the codomain to make a function surjective, but it wouldn't change injectivity
if you had f(x) = x^2 as a function from R to (negative reals) that wouldn't be a well-defined function, since most inputs would produce outputs not in the codomain
@heavy basalt Has your question been resolved?
Why? If we define x^2 this way, each line parallel to the x axis that we'll draw, will intersect the function at 1 point or not ay all
every input from a function's domain must be assigned to an output in the codomain
Because the function essentially is just the origin point
your function must have a valid output for every input in the domain
if you want to restrict the domain to the origin as well then it works, but otherwise not
Why? There are functions with discontinuies, in which there is a value in the domain that doesn't have a valid output in the codomain
strictly speaking the domain does not include those values
e.g. the usual domain for the function f(x) = 1/x would be R \ {0}, the nonzero real numbers
Or am I confusing domain with "preimage" I believe it's called in English?
What about change codomain to 0?
∀x₁, x₂ ∈ ℝ, f(x₁) = f(x₂) → x₁ = x₂
f: ℝ → {0}
f(x₁) = f(x₂) ⟶ x₁ = x₂
¬(x²(x₁) = x²(x₂)=0 → x₁ = x₂) --- oh no it does imply that because the only thing is 0 that can be sent to 0 via x^2, maybe
x²(x₁) = x²(x₂)=0 → x₁ = x₂
∵ ∃!r∈ℝ r²=0, r=0
there is a notion of "partial functions" where not every point in the domain must have a defined output, but these are not used very often
ℝ---x²--->0
the problem remains that "x^2" is not a valid formula for a function R -> {0}
Oh wait I don't think my logic holds there
So the function 1/x can be mapped from R to R but its domain would be R \ {0}?
And not R?
yes, but we wouldn't say it's mapped "from R to R", we would say it's mapped "from R \ {0} to R"
what do you think?
injectivity: ∀x₁, x₂ ∈ ℝ, f(x₁) = f(x₂) → x₁ = x₂
change co-domain to 0: x² : ℝ → 0,
so x²(x₁)=x²(x₂)=0 → x₁=x₂=0
∵ ∃!r∈ℝ r²=0, r=0
again, you are presupposing the function is well defined in the first place, which is precisely the problem (it is not well defined)
also your logic makes no sense, in the third line you just assert it's injective with no proof. i suggest writing out your proof in words
I wrote I think, if for any input from ℝ you get the same output, then the inputs were the same:
x²(x₁)=x²(x₂)=0 → x₁=x₂=0
that's the definition of injectivity. you have not proven that the function satisfies that definition
What else does it need?
maybe
proposition:
change co-domain of x² to 0: x² : ℝ → 0
→ ∀x₁, x₂ ∈ ℝ, x²(x₁) = x²(x₂) → x₁ = x₂
proof:
x² : ℝ → 0,
∀ x₁,x₂∈ℝ, x²(x₁)=x²(x₂)=0, because x² maps to 0
∃!r∈ℝ r²=0, r=0,
∴ x²(x₁)=x²(x₂)=0 → x₁=x₂=0
ok still we have the problem, your function remains not well-defined
∀x ∈ ℝ, ∃! y ∈ 0, x²(x) = y,
for x²: ℝ → 0,
∀ x, x²(x) = 0
every input from ℝ has a unique output, 0 in the codomain {0}
sure but that's just a different function at that point
because the formula is f(x) = 0, not f(x) = x^2
but then how do you change the codomain?
you can only change the codomain while keeping the same formula as long as the image is a subset of whatever codomain you choose
can we change the codomain of x² : ℝ ⟶ ℝ so it becomes injective?
f : domain ⟶ codomain
codomain change ℝ to 0, f becomes injective
x²: domain ⟶ codomain
x²: ℝ ⟶ ℝ not injective
x²: ℝ ⟶ 0 injective
you cannot change the codomain of a function (while keeping the same formula!) to make it injective
only changing the domain can work for that
what is the formula? x ⟼ f(x)?
something like that
x ⟼ x² ?
strictly speaking the same graph, pairs (x,f(x))
@heavy basalt Has your question been resolved?
Graph(x² : ℝ → ℝ) = { (x, y) ∈ ℝ × ℝ | y = x² }
Graph(x² : ℝ → 0) = { (x, y) ∈ ℝ × 0 | y = x² }
second one is not a valid graph of a function
Oh I think I see what you mean, every element in ℝ should have an output, but for example 1² doen't map to anything, because {0} has only one element
but is that not a slightly different concept?
f : ℝ ⟶ ℝ domain codomain are sort of types? so don't have to include all elements
preimage and image
all elements of the domain must be included for a relation to be a function
Closed due to timeout
Use .reopen if this was a mistake.
What if you change the codomain to something larger, where source is recorded?
like f⁺ : ℝ → ℝ × ℝ
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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 change codomain of x^2 : ℝ ⟶ ℝ to make it injective
Change the codomain to the image
dont you want to change the domain
Oh right injective
What if you change the codomain to something larger, where source is recorded?
like f⁺ : ℝ → ℝ × ℝ
Yeah so there is no one way to do that

at that point youre just straight up changing the function
f⁺: ℝ → ℝ×ℝ
f⁺(x) = (x², x)
1 ↦ (1,1)
−1 ↦ (1,−1)
→ injective
thats not wrong but not the intention
the idea is to replace the Rs with subsets
we still want the same formula f(x)=x^2
Oh I didnt see that you only want to change the codomain. then yeah you'll have to use something like that
This seems kind of pointless
yeah a bit
Because you make the function injective while forgetting its original structure
someone asked this question, and I am learning about injectivity so I am curious
you can now ask someone about the same question who can ask someone etc
Damn my question gained some interest
your friend's question, maybe they were asked by someone also
I still dont get that
Since you still say about x^2 that it's mapped from R to R and not R to R+ and 0
Nah it was his originally, we answered some questions together and then the question about x^2 came up and he asked the question I wrote
that's a good point
I know that this is matter of pure definitions, but I think I need to get better at that, especially in English because I don't study in English
Like there is domain, range, image, and something that relates to domain the same way image relates to range
f : ℝ → ℝ
f(x) = x²
maybe this is to say, the domain is ℝ, the codomain is ℝ, where f(x)=x^2
While the image is {x>=0}
preimage ⊆ domain
image ⊆ codomain ?
yes but you should be careful
there is an image of a function
there is no preimage of a function
only a preimage of a set under a function
Thank you @stone stump for this! I don't yet understand this, but I find it interesting, and I found literature on this just now
@heavy basalt check https://webhomes.maths.ed.ac.uk/~tl/ast/ast.pdf writes about just this , domain, codomain, image, etc, and look has the same example of changing the codomain of x^2
Thank you everyone 🙏
@fierce matrix 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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
@frank cloud Has your question been resolved?
Channel closed due to the original message being deleted.
If you did not intend to do this, please open a new help channel,
as this action is irreversible, and this channel may abruptly lock.
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
.close
Closed by @copper harbor
Use .reopen if this was a mistake.
they're a known spammer
rip to that
ah
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.
• Do not immediately ping people or roles. After 15 minutes, feel free to ping <@&286206848099549185> once.
• 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.
not a concrete question but why i the fuction f(x)= x^x only defined for postive numbers?
well, for starters
(-1/2)^-1/2?
what is that supposed to be
?
its discontinious before 0?
yeah
why doesnt atleast show the points that do work?
well for the points you can define
because -1/3 isn't an exact value that a computer can store
computers cant do that
so its more of computational limitation and to make the fuction easier to understand?
I guess you can technically define k^k when k is a negative integer
But when you plot functions on desmos
usually the argument is a float type
and so there's no good way to define x^x for any those values, even when there are rare exceptions
my teacher told me functions like f(x)=1, when x is rational, 0 when x is irrational
cant be plotted by computers because they change values so rapidly in a discontinuous manner
i see
oh thats the dirichlet fuction

