#help-43

1 messages · Page 40 of 1

prime loom
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ohh k I found this

urban flicker
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2

winged lion
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.

prime loom
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srry for wasting time lol

urban flicker
#

anyway, it's less then f(n)=n

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that's enough

prime loom
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f(n) <= n

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yeah

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so f(n) is decreasing

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so upper bound is x_0,

devout wraith
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i think its right

urban flicker
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thank you @prime loom

prime loom
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wait tho

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my proof doesnt work for the 2

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for 2 the bounds are sqrt(2) and x_0 I believe

urban flicker
#

how to prove that converges at sqrt(2)

prime loom
#

AM-GM?

urban flicker
#

uhmm

prime loom
#

$f(t) = 1/2(t + 2/t) >= sqrt(t * 2/t)

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so thats sqrt(2)

urban flicker
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$f(t) = 1/2(t + 2/t) >= sqrt(t * 2/t)$

boreal girderBOT
#

Starland

prime loom
#

y

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't's cancel

urban flicker
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aha

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and upper bound with n..?

prime loom
#

you can do it with derivatives

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$f(t) = \frac12(t+\frac2{t})$, then
$f'(t) = \frac12(1-\frac2{t^2})$

boreal girderBOT
#

AlmondAxis987

prime loom
#

for $t \geq \sqrt{2}, f'(t) \geq 0$

stoic crescent
#

Hello

boreal girderBOT
#

AlmondAxis987

prime loom
#

and t is always greater than sqrt(2) as its lower bound

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so f(t) is increasing

urban flicker
prime loom
#

ok etc (End of Thinking Capacity)

urban flicker
#

it has a lower bound sqrt2 and converges to sqrt2?

prime loom
#

lower bound is def. sqrt(2)

urban flicker
#

uh okay

prime loom
#

<@&286206848099549185> can someone help this man and me out pls?

mighty lance
prime loom
#

Prove and find the bounds of the recursive sequence $x_{n+1} = \frac12(x_n+\frac2{x_n})$

boreal girderBOT
#

AlmondAxis987

prime loom
#

we have found lower bound sqrt(2)

urban flicker
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sure it's not increasing

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it converges at sqrt2

prime loom
urban flicker
#

compare x_n and x_(n-1)

urban flicker
prime loom
#

ig

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$f(t) -t = \frac{2-t^2}{2t}$

boreal girderBOT
#

AlmondAxis987

prime loom
#

for all t>=sqrt2, this is negative lol

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and t is >= sqrt2 as thats lower bound

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so $f(t) < t$

boreal girderBOT
#

AlmondAxis987

prime loom
#

is this correct?

#

anybody?

winged lion
#

I am sure you cannot just replace x_n with t because x_n can be any arbitrary sequence, right?

prime loom
#

?

prime loom
fathom raven
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It does not matter if its replaced I think

prime loom
#

yeah

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it starts with f(x_0) = x_1

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then f(x_1) = x_2

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and so on

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and all x_n >= sqrt2

fathom raven
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Yes

prime loom
#

so it is a monotinicly decreasing function

prime loom
#

and its always >=sqrt(2)

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so it converges to sqrt(2)?

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@urban flicker I think this was the answer?

urban flicker
#

indeed

prime loom
#

ok cul

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I feel a little dumb that it took me that much time tho

fathom raven
#

So with just that info is enough to say it converges to sqrt2?

prime loom
#

well thats yer questions solution done

winged lion
prime loom
#

so?

winged lion
#

it doesn't prove anything

prime loom
#

I am using t to analyze the function and the restrictions on t placed in the analysis are placed on the recursion too

prime loom
winged lion
#

Induction would be a better choice to show possibly that sqrt(2) is a lower bound

urban flicker
prime loom
#

just not stating each step individually

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f(x_n) < x_n

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so x_n+1 < x_n

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and x_n+1 >= sqrt2

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so by induction x_n converges to sqrt2

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also another way is to just set x_n+1 = x_n

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in the recursion funxtion

thorny kestrel
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if we suppose x_0 > 0, then clearly the sequence is positive. with AM-GM we find one lower bound to be 1.
then for t > 2, f - id is less than a strictly negative constant so the sequence is decreasing, less than x0, and will be less than 2 after a certain point
we can then show that x_n is strictly bigger than a constant C that is strictly more than 1
and when t is between C and 2, f' is < 1 thus proving both boundedness and convergence

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x_n can be strictly decreasing & bigger than sqrt2 without converging to sqrt2

prime loom
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oh so like it can converge to 1.5 and the conditions still hold

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interesting

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I have no idea how to find the limit of the sequence then

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ohh lol I just solved by mistake

prime loom
#

here

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this gives x = sqrt2

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if you set f(x) = x

fathom raven
#

Idk I am new in how to do proofs

prime loom
#

I am not, but still I struggle

fathom raven
#

Thanks for discussing these topics it helps me explore the different views of everyone

prime loom
#

K Bai

#

OP close channel

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*If youre done

#

@urban flicker

compact pewterBOT
#

@urban flicker Has your question been resolved?

#
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thorny kestrel
compact pewterBOT
thorny kestrel
#

ok mb it works

#

nvm nvm

#

.close

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pseudo wasp
compact pewterBOT
kind viper
#

!status

compact pewterBOT
#
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
pseudo wasp
#

Ehhh ig no idea

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All I got was 18 * {11.....1(51 times)}^2

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And I am somehw supposed to get 52nd digit

kind viper
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well that's a good start actually

pseudo wasp
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Okay....... any hints or patters?

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I am just like 111....1^2 is always in the form of 123.........321

kind viper
#

try to look at the squares of 1, 11, 111, 1111 etc.

pseudo wasp
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but ther than that idk

kind viper
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why did you say "form" twice?

pseudo wasp
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Ehhh cause doesn't it end with what it starts

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like 12321

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in this way

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1234321

kind viper
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no but why use the word "form" twice

pseudo wasp
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so 123.....321

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oh nvm that

kind viper
#

also consider looking at the expansion of $(x^n + x^{n-1} + \dots + x + 1)^2$ more generally

boreal girderBOT
pseudo wasp
#

So......... eh........ well isn't this only true upto 9 1's

kind viper
#

and also expressing your number made of 51 ones as that but with n=50 and x=10.

kind viper
pseudo wasp
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okat....

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ya

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i know that..... :)

pseudo wasp
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see if I can find some pattern

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Ok Just a hint

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I tried to use Gp right

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(X^n+1-1 ) /x-1

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so I would get smth like eh.....( 10^51-1/9)^2

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@kind viper

kind viper
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GP will be kind of a no-go here sorry

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also i am going to be slow to respond bc im cooking myself food rn

kind viper
#

the 52nd digit from the right in any number is the 10^51 place

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figure out how to account for that

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and all the carries from places below

pseudo wasp
#

ehhh

kind viper
#

and do not forget about the 18 factor

dusky quartz
#

maybe try smaller cases.

i.e. 333×666
3333×6666
note any patterns you notice

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then try generalizing it

kind viper
pseudo wasp
#

Bruh

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I truly don't understand

pseudo wasp
#

in that way it will be one

compact pewterBOT
#
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prime loom
#

@pseudo wasp

#

I can give a hint to solve the question you have above

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if yu want, that is

#

ehh k whatever

compact pewterBOT
#
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west isle
#

hi can I get some help? I’m unsure of my answer ☹️

viscid canopy
#

money from sales tax is 9.4% of the money from the merchandise

west isle
#

??

viscid canopy
#

what are his two sources of money?

west isle
#

1219.58 and 9.4

viscid canopy
#

no, the 1219.58$ is the total he earns from the two sources of money

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what is his job?

west isle
#

artist?

viscid canopy
#

yes and what does he sell

west isle
#

pottery.

viscid canopy
#

good. So he sells pots and everytime he sells it, he taxes 9.4% money of the total sale. If he sells $100 worth of pots in a day, he earns an additional $9.4 from the tax

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Does that make sense?

west isle
#

yes and no? that’s different from what I got when I solved it eeveethink

viscid canopy
#

I was giving an example

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What was your working btw?

west isle
viscid canopy
west isle
#

1.00777 = x

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and 9.47

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because I had to solve for x

viscid canopy
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what is x here

west isle
#

1219.58 = x + x ( 9.4)

viscid canopy
#

ah here is the problem

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it is 9.4%, not 9.4 itself

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9.4% = 0.094

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9.4% of 100 dollars is 9.4 dollars, not 9.4*100 dollars

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so the actual expression is: 1219.58 = x + x (0.094)

west isle
#

OH OH

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I GOT IT

west isle
viscid canopy
#

you misinterpreted the meaning of percentage but the idea was correct

west isle
viscid canopy
#

for x?

west isle
#

yes

viscid canopy
#

,w solve 1219.58 = x + x (0.094)

boreal girderBOT
viscid canopy
#

,calc 609790/547

boreal girderBOT
#

Result:

1114.78976234
west isle
#

unless I simplify it

viscid canopy
#

hmm that is supposed to be x

west isle
#

erm

viscid canopy
#

how did u get 1219.486

west isle
#

WAIT

#

I DID

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oops

viscid canopy
#

did you figure out the issue? mikuyay

west isle
#

yes

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wait am I putting

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1219.48/ 1114.789

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like the full numbers for 1114.789?

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or is it just 1114.78?

viscid canopy
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for x, just 1114.79

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because we are rounding to the nearest cent

west isle
#

o

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this is what I have rn

viscid canopy
#

im not sure what you are doing here

#

1219.58 = x+0.094x
hence
1219.58 = 1.094x

Do you agree so far?

west isle
#

hey so

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I am still fixing my equations.

viscid canopy
#

ah okay, let me know once u fix them!

west isle
#

1.094x??

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where are u pulling that from 💔

viscid canopy
#

we are combining terms

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as an example, what is x+x?

west isle
#

im overwhelmed.

viscid canopy
#

oh I apologize

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have you seen stuff like x+2x = 5 before?

west isle
#

???

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x+2=5 you mean or?

viscid canopy
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yeah like in general

west isle
#

yeah I know x+2=5. not x+2x=5.

viscid canopy
#

okay so in algebra (the field of math we are doing right now), when you see something like
x+3x
we can combine the terms to get
x+3x = 4x
just like 1+3 = 4

#

with this logic, what would x+9x be?

west isle
#

umm

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I don’t know, this is just overwhelming me more.

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I think im going to stop here.

viscid canopy
#

alright

#

you may type .close

#

to close the channel

west isle
#

.close

compact pewterBOT
#
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compact pewterBOT
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mystic crater
#

hey

compact pewterBOT
mystic crater
#

I have the starting equation

#

5sin(2x)cos(2x) = sin(2x)

#

so then i divide both sides by cos(2x)

native shard
#

,av 82jz

boreal girderBOT
#
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mystic crater
#

leaving me with

5sin(2x) / cos(2x) = sin(2x) / cos(2x)

which is

5tan(2x) = tan(2x)

#

which doesnt look right

kind viper
#

LHS is incorrect for one

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and also you should be really careful dividing both sides by cos(2x) unless you wanna lose solutions

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but also 5sin(2x)cos(2x) divided by cos(2x) does NOT give 5 sin(2x) / cos(2x).

mystic crater
kind viper
#

whichever x's would satisfy cos(2x)=0 might be solutions but after this division they won't be.

nocturne gate
kind viper
#

also, third thing: i don't even think dividing by cos(2x) helps you at all.

kind viper
mystic crater
kind viper
#

you won't accomplish it that way.

mystic crater
nocturne gate
#

but dont

mystic crater
#

possibly

viscid canopy
#

that is why, the optimal path is to take everything to one side and factorize

nocturne gate
kind viper
#

non trigonometric, for simplicity

mystic crater
#

sure

mystic crater
viscid canopy
#

yups!

kind viper
viscid canopy
#

this way, you get two factors that can possibly be equal to 0

kind viper
#

on the one hand, you can tell it has solutions x=0 and x=7 by a similar technique: put all terms on one side and factorize -- this gets you x(x-7) = 0.

#

on the other hand, if you give in to the temptation to divide by x immediately, you are left with x = 7 -- and now the solution x=0 is lost.

mystic crater
#

does this only happen when x (or the solution) = 0?

kind viper
#

rather it's when the expression by which you divide equals 0.

#

bc again, division by zero no good.

#

so funny business like this happens precisely when you divide by maybe-zero.

mystic crater
kind viper
#

note that division by x, or another variable quantity that may be 0, isn't wrong in itself -- it simply requires knowing the consequences of doing such a thing.

kind viper
#

one counter-measure is to explicitly look at whichever x's might be lost as solutions, and note which ones among them really are solutions and write that down explicitly on the paper -- that way, they'll still be there and you'll still be able to put them back in the solution set.

mystic crater
#

.close

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mystic crater
compact pewterBOT
mystic crater
#

.close

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frigid furnace
#

yo guys

compact pewterBOT
frigid furnace
#

whats the smartest way to integrate 6arctan(8/w)dw

#

i mean

#

quicket

#

DI method?

pseudo shale
#

U sub

#

Then By parts

frigid furnace
#

I did

#

by parts

#

then u sub

#

.close

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eternal pulsar
compact pewterBOT
boreal girderBOT
eternal pulsar
#

So far so good?

eager cipher
#

can someone helpme wth something quick, its a really easy thing by the looks of it but i just have a little question

short lantern
#

id write it as a column vector of zeros

compact pewterBOT
eager cipher
#

why do you subtract 8ab from 15ab

#

oh sorry

short lantern
#

!occupied

compact pewterBOT
#

Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #❓how-to-get-help for instructions).

eager cipher
#

sorry sorry

eternal pulsar
#

Too lazy breadhehe

#

The problem comes when row reduce

short lantern
#

yes, you can see the sums of the columns are all 0

eternal pulsar
#

Ik that R1+R2=-R3

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So we can "replace" the equation 3 with the equation w1+w2+w3=1

#

Right?

short lantern
#

wha

slate sand
#

Yea

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Thats from the definition of a stochastic matrix

eternal pulsar
#

Oh ok

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Good to know

short lantern
#

oh ok

eternal pulsar
#

Ok wait Lmao

boreal girderBOT
eternal pulsar
#

Ok so now aug should be

boreal girderBOT
eternal pulsar
#

Ow lag

#

Aaaaaaalright

#

So first row operation will be R2-2R3->R3

boreal girderBOT
eternal pulsar
#

Lets seeee

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Next one will be 2R1+9R2->R2

boreal girderBOT
eternal pulsar
#

Good god

#

Y'all have any tips before i dive into this hell of a calculation?

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Ok I feel like I did something wrong

#

Cause it's gonna result in w1=w2=w3=0

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Sooooooooo

#

<@&286206848099549185>

slate sand
#

Did you try put it in a matrix calculator

eternal pulsar
#

Lemme se

#

,w rref {{-0.9, 0.2, 0.3, 0}, {0.2, -0.7, 0.4, 0}, {10, 10, 10, 0}}

eternal pulsar
#

Oh well

#

💀

#

So da method is wrong

#

,w rref {{-0.9, 0.2, 0.3, 0}, {0.2, -0.7, 0.4, 0}, {0.7, 0.5, -0.7, 0}} with fractions

#

Gah

#

So

boreal girderBOT
keen granite
#

mult and div by 10?

#

then shouldn't the bottom row be all 10s instead of all 1s?

compact pewterBOT
#

@eternal pulsar Has your question been resolved?

eternal pulsar
#

,w rref {{-0.9, 0.2, 0.3, 0}, {0.2, -0.7, 0.4, 0}, {10, 10, 10, 0}}

boreal girderBOT
eternal pulsar
#

Aw

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Damnit

#

You get the point

eternal pulsar
keen granite
#

[
\begin{bmatrix}
-9&2&2\
2&-7&4\
10&10&10
\end{bmatrix}
]

boreal girderBOT
#

PajamaMamaLlama

eternal pulsar
#

Yeah...

#

No clue

keen granite
#

wait do I suck at math?

eternal pulsar
#

This stupid questions and fractions

keen granite
#

,calc -9*lcm(2,9,10)

boreal girderBOT
#

Result:

-810
keen granite
#

,calc -810/180

boreal girderBOT
#

Result:

-4.5
keen granite
#

guess I do KEK

eternal pulsar
#

wolfram won't give fraction output

keen granite
boreal girderBOT
#

PajamaMamaLlama

keen granite
#

[
\begin{bmatrix}
-180&40&40\
0&-59&40\
0&220&220
\end{bmatrix}
]

boreal girderBOT
#

PajamaMamaLlama

eternal pulsar
#

Ugh

#

Well I got it

#

may or may not have asked gemini to do the brunt of the work

keen granite
eternal pulsar
#

I gaev up

#

There's no way shit like this will appear on the exam

keen granite
#

well wouldn't the full augmented matrix be:
[
\begin{bmatrix}
-9&2&3&0\
2&-7&4&0\
7&5&-7&0\
1&1&1&&1
\end{bmatrix}
]

boreal girderBOT
#

PajamaMamaLlama

keen granite
#

why is that 1 in a_44 so far out? kek

eternal pulsar
#

OHHHHHHHHHHHH my lord

#

I'm dumb

eternal pulsar
#

I guess I can do it but I make sill ymistake

keen granite
keen granite
#

just make sure it doesn't during an exam happy

#

easier said than done tho happyb

eternal pulsar
#

Yep bleak

#

Aight cya, I'm VERY tired

#

.close

compact pewterBOT
#
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keen granite
#

,ti ;(

boreal girderBOT
#

The current time for exiled_hype is 06:33 PM (EDT) on Fri, 29/08/2025, the same as xxmrfancyu2xx!

compact pewterBOT
#
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livid spoke
#

How do I do this

compact pewterBOT
bleak dock
livid spoke
#

yes

bleak dock
livid spoke
#

so i just do that for both?

bleak dock
#

the domains of both functions?

bleak dock
#

and then note your domains, so for the inverse you will have $y \le 0$ and $y > 0$

boreal girderBOT
bleak dock
#

h = y here

#

or actually, just find what h is when r = 0, so that would be 1 and 1 respectively, and that gives you the domains, cause you swap h and r

livid spoke
bleak dock
#

cause you need the domain to be in terms of x surely

livid spoke
#

so what are the domains again?

livid spoke
bleak dock
livid spoke
#

wait wdym

bleak dock
#

if you've done it you can just say what you think the domains are

livid spoke
bleak dock
#

okay so do you agree that (x, y) = (0, 1) is where both of those piecewise functions meet?

#

the functions break at x = 0

livid spoke
#

okay

bleak dock
#

yeah, and for the inverse functions

#

you just swap y and x

#

so that gives you which point?

livid spoke
#

1

bleak dock
#

well, (1, 0)

#

but the new x is indeed 1

bleak dock
boreal girderBOT
livid spoke
#

like where you got it from

bleak dock
#

and you get 1 and 1

livid spoke
#

ohh in the orginal thing

bleak dock
#

yeah

livid spoke
#

i thought i had to do r=0 on my new ones

bleak dock
#

yeah you could do it that way but I realised this shorter way

#

you could indeed solve for inverse of 1st function $\le 0$ and inverse of 2nd function $> 0$

#

it's not that much longer but still

boreal girderBOT
bleak dock
#

it'd be repetitive actually

livid spoke
bleak dock
#

if you're done type .close

compact pewterBOT
#

@livid spoke Has your question been resolved?

compact pewterBOT
#
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deft forum
#

How do i do this

compact pewterBOT
deft forum
hushed magnet
#

yeah its not well written imo

#

my interpretation: the clock in the mirror looks like its 6:45. so draw that, then mirror it, then read what time it shows now

kind viper
#

i think thats the only thing that makes sense yeah

compact pewterBOT
#

@deft forum Has your question been resolved?

deft forum
#

This is ment to be a mock test so that pretty much can't be the solution

hushed magnet
#

why not

#

its definitely not any other subject

deft forum
#

Wait I solved it it's either 6:15 or 12:45

#

Depends on which axis which it didn't states

hushed magnet
#

neither one of those

#

where is the hour hand

kind viper
prime loom
#

is mirroring that high-level?

compact pewterBOT
#

@deft forum Has your question been resolved?

#
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compact pewterBOT
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native veldt
#

can someone help me with this integral? I really cant find which convergent theorem i can use to bring the limit inside

compact pewterBOT
#

@native veldt Has your question been resolved?

native veldt
#

I now have that the integrand goes to zero, but i don't know how to proceed.

compact pewterBOT
#

@native veldt Has your question been resolved?

sage sonnet
#

<@&286206848099549185> 💔

rotund sphinx
# native veldt can someone help me with this integral? I really cant find which convergent theo...
native veldt
#

But it's more to get the hang of changing the integral and limit from place, not just to solve it

hazy yew
#

Niemand kan bro helpen 🙏

native veldt
#

Ja ik denk da ik er gewoon mee ga moeten leven 😢

#

help jij mij

hazy yew
#

Ik kan je spijtig genoeg niet helpen 😔

native veldt
hazy yew
#

Ik heb daar niet de capaciteiten voor

native veldt
#

.close

compact pewterBOT
#
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compact pewterBOT
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strange pendant
compact pewterBOT
strange pendant
#

analize the existence of this limits and if they exist, say their value

winged lion
#

🐻‍❄️

strange pendant
#

take for example y = x and x = 0

#

we get

winged lion
#

(in case you wanna save time use polar coordinates)

strange pendant
strange pendant
#

what is r then?

winged lion
#

r goes to 0

strange pendant
#

and t?

winged lion
#

t is arbitrary

#

u let it vary

#

letting t vary is like taking an arbitrary path

strange pendant
thorny kestrel
#

the numerator is y

winged lion
#

x²y

#

you can also simplify the denom

#

you can prove the limit with the squeeze theorem (use that sine and cosine are bounded)

strange pendant
winged lion
#

yea

thorny kestrel
#

Another way to prove this is using AM GM, though polar coordinates are probably the more general approach

strange pendant
turbid surge
#

Bro how are you already doing multivariable calculus ?

winged lion
#

yea and if you take the abs value and bound it you are done

strange pendant
#

anal 1, is multi var calc

turbid surge
#

I mean usually multi var calc is done after doing a calc 1 course with one variable idk

#

Ig its different for different unis

strange pendant
#

calc 1 course was what we covered in pre university math, idk

turbid surge
#

Oh

strange pendant
#

intro to mathematical analysis

turbid surge
#

Oh i see thats why

strange pendant
#

I am also taking this sem, algebra I which is intro to proofs, relations, basic set theory, functions, combinatorics, polynomials, and basic diophantic eqs, aswell as modular arithmetic

winged lion
#

crazy start

strange pendant
strange pendant
#

cos^2 is bounded between 0 and 1?

winged lion
#

Yea

strange pendant
winged lion
#

,, \lim_{r\to0} |f(r,\theta)| = \lim_{r\to0} r\cos^2(\theta)|\sin(\theta)| \le ?

strange pendant
#

le?

boreal girderBOT
strange pendant
#

ahh

winged lion
#

write it

strange pendant
strange pendant
#

the absolute value, no?

#

I am maybe tripping

winged lion
#

Yes

#

,, (0 \le) r\cos^2(\theta)|\sin(\theta)| \le r\to0

turbid surge
winged lion
strange pendant
winged lion
#

no

#

You still have r left

strange pendant
#

r tends to 0

#

lim r -> 0

winged lion
#

Yes

strange pendant
#

what about it?

winged lion
#

Why did you writr then 1

strange pendant
#

what about lhs of the ineq

#

why the absolute value ?

winged lion
#

Dont write limit

strange pendant
#

ok

winged lion
#

Squeeze theorem says since lower and upper bound go to 0, then so must the middle term

strange pendant
#

its a completely different limit if we do that

winged lion
#

no

strange pendant
#

like, it would be simpler to argue that
since image of sin is [-1,1] and image of cos^2 is [0, 1] it follows that the image of cos^2(t)sin(t) is [0,1]

winged lion
#

You can bound it with 0

#

You dont have to take -1

strange pendant
#

but both things are equivalent

strange pendant
boreal girderBOT
winged lion
#

I wrote the 0=< to make clear its not negative

#

If you resolve the abs value you get your function

#

Thats what I meant (I am cooking right now)

strange pendant
#

then what?

#

the problem is that I am having trouble concluding that its equal to 0

boreal girderBOT
strange pendant
#

that is equal to 0

winged lion
#

Then what

strange pendant
#

but proving the original limit, is equal to

#

0

winged lion
#

Pull up the squeeze theorem

strange pendant
winged lion
#

g=-r
h=r
L=0

#

So f -> L as well

winged lion
strange pendant
#

actually, I think that works

#

we dont need the absolute value on sin

winged lion
#

huh?

#

I just wrote the same thing shorter

#

I am on phone

strange pendant
winged lion
#

Remove the lim

winged lion
strange pendant
#

my bad dude

#

im cooking

#

some milanesa de pollo

winged lion
#

yes

strange pendant
#

I appreciate the help

#

how did you knew this was always zero?

#

also, cant i just use polar coordinates for all of this multivariable limits?

winged lion
#

not all

#

its like asking, can i always use a usub for integration

#

different tools for different problems

#

but when i see the x²+y² sure go with 🐻‍❄️

strange pendant
#

i appreciate it dude

#

.solved

compact pewterBOT
#
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turbid surge
#

Given $\tau \sigma \tau^-1 = ( 1 2 5 4) \in S_7$
Given permutation $\tau \sigma^k \tau^-1$ is the inverse of $(\tau \sigma \tau^-1)^{40}$ find k

turbid surge
#

How do i do this

boreal girderBOT
#

prograce

turbid surge
#

I know that ord($(\tau \sigma \tau^-1)^{40}$)=1 and ord($\tau \sigma \tau^-1$) =4 and that the permutation is odd from the previous parts

boreal girderBOT
#

prograce

kind viper
#

$\tau^{-1}$ first and foremost

boreal girderBOT
kind viper
#

also other wordbadtex

turbid surge
turbid surge
kind crane
#

should simplify $(\tau \sigma \tau^\inv)^{40}$ first

boreal girderBOT
#

riemann

kind viper
#

gonna second riemann tho

turbid surge
#

Oh,

kind viper
#

alternatively

#

(tau sigma tau^-1)^4 = e

turbid surge
#

I could simplify it to (tau sigma tau^-1)^10 then

kind viper
#

simplify WHAT to that?

turbid surge
#

I think im looking at tau sigma tau^-1 as a whole when i should be looking at sigma=(1 3 4 6)

turbid surge
kind viper
#

a^4=e does NOT imply a^40=a^10

turbid surge
#

Can I get a hint?

turbid surge
kind viper
#

yes

#

a^40=e indeed

turbid surge
#

So I need to find k such that $\tau \sigma^k\tau^{-1} = e^{-1}=e$

boreal girderBOT
#

prograce

turbid surge
#

And since o($\tau \sigma \tau^{-1}$)=4 then k=4 ?

boreal girderBOT
#

prograce

upbeat gorge
#

is this the smallest possible k?

turbid surge
#

Yes?

upbeat gorge
#

you seem a little unsure - can you back it up?

turbid surge
#

Since the order of the permutation is 4, then any smaller power would not give me the identity by definition

upbeat gorge
#

exactly, so you can be confident in your answer :D

turbid surge
#

Problem is my answer is wrong haha

#

Idk where it went wrong tho

upbeat gorge
#

ah.

turbid surge
#

The solution is supposed to be k=8

#

I'm quite lost on how to get that

upbeat gorge
#

well, i double checked by hand and also by theorem, and $\mathrm{ord}(1 ; 2 ; 5 ; 4)$ definitely seems to be 4

boreal girderBOT
#

haseeb

upbeat gorge
#

is there more to the solution with k=8?

#

oh wait it's $\tau \sigma^k \tau^{-1}$, not $(\tau\sigma\tau^{-1})^k$

#

🤦‍♂️

boreal girderBOT
#

haseeb

upbeat gorge
#

so we want $\tau\sigma^k\tau^{-1} = e$

turbid surge
#

Hahahah

boreal girderBOT
#

haseeb

turbid surge
#

Oh right

upbeat gorge
#

can you simplify something here? perhaps make something reduce to e?

#

wait that also gives k=4 sully

turbid surge
#

I think our answer is right, I just realized that 4 is not in the options,,

#

Sorry yes 4 is correct

#

8 is also correct and since it is in options

#

Wow that was a huge time waste haha

upbeat gorge
#

ohh of course oopsie

turbid surge
#

Any multiple of 4 is correct... so 8 is the answer here

#

Sorry I didn't realize 4 wasn't in the options

#

.solved

compact pewterBOT
#
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upbeat gorge
#

. its on me too, didnt say smallest value opencry

eternal pulsar
#

s

compact pewterBOT
eternal pulsar
#

Ok

boreal girderBOT
eternal pulsar
#

Now I wanted to go by induction

boreal girderBOT
eternal pulsar
#

Hence true

#

Now we assume it true for n=k, and want to prove it for n=k+1, k>=2

#

The other stuff can be ignored since they will not be polynomial of degree k

boreal girderBOT
eternal pulsar
#

So since it is true for n=2 and n=k+1, k>=2, it must be true for n>=2, hence proven

#

Is this good?

compact pewterBOT
#

@eternal pulsar Has your question been resolved?

azure vault
#

and for constant coeff what did you do?

eternal pulsar
#

Well that's just f(0)=det(A-0lambda)=det(A)

eternal pulsar
#

Shouldn't be too hard

boreal girderBOT
eternal pulsar
#

Since there's n-2 entries with a lambda term, we have that the degree of the polynomial formed will be at maximum degree n-2=k-1

#

Since the same thing will happen for the other minors, the degree of stuff <= k-1

#

@azure vault is this good? I know its rough but I'm too lazy to elaborat emuch

#

<@&286206848099549185>

eternal pulsar
#

<@&286206848099549185> afraid

azure vault
#

yes this should be good

eternal pulsar
#

Typa timing lmao

azure vault
#

basically the minors from expanding

#

they are all k*k matrices

#

but they all get a row or column destroyed

#

where there was a lambda term

#

so only k-1 terms with lambda

eternal pulsar
#

awight

#

ezpz, cya

#

.close

compact pewterBOT
#
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compact pewterBOT
#
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flint wing
#

i need help starting 2a iii)

compact pewterBOT
spark folio
#

what did you get for i and ii?

#

like yes/no

flint wing
#

it is not injective and it is surjective

spark folio
#

good

#

so, you can find the trivial preimages for this right?

flint wing
#

like 2,4,8,16,...?

spark folio
#

preimages are gonna be tuples

#

you might also wanna recall the rules of exponents

#

like for different values of k, the preimages gonna differ

flint wing
#

uh so

#

wat do i do

spark folio
#

lets start with some specific values of k

#

lets say you got k=2

#

what can you tell about its preimage(s)

flint wing
spark folio
#

yes

#

and uhh, format it better? like (2,2) and (4,1)

flint wing
#

{(2,2), (4,1)}

spark folio
#

what about if k=6?

#

no need to calculate the stuff exactly

#

I want what insight can you get from the values of k

flint wing
#

so we want the pairs (m,n) such that m^n = 2^6

spark folio
#

yes

#

so, how does that k affect the possible values of m and n?

flint wing
#

well like depending on k the amount of pairs u get are different i think

spark folio
#

ofc

spark folio
flint wing
#

are we trying to look like more generally ?

#

not like for specific k now

#

so i guess

#

like

#

we are solving m^n = 64

#

since output must be power of 2 then m has to be power of 2

spark folio
#

yep

#

and what about n?

flint wing
#

well if we let like m = 2^a so

#

m^n = (2^a)^n = 2^(an)

spark folio
spark folio
flint wing
#

so 2^an = 2^6 if k=6

#

so therefore an = 6 and we have to find a and n that make an=6

#

we can have

a = 1, n = 6
a = 2, n = 3
a = 3, n = 2
a = 6, n = 1

spark folio
#

good, so this time you got 4 different tuples of possible preimages

#

and ofc, by now you must have realized how that depends on k

flint wing
spark folio
#

well, yea

#

thats a part of it

#

specifically, I am talking about the factorization of k

spark folio
#

each factor of k is gonna yield a different pre-image

flint wing
#

do we solve for n?

#

n = k/a

spark folio
#

hmmcat how are gonna solve for n when you only know k and not a

flint wing
#

well like we need an = k right

#

so n = k/a

spark folio
#

imo going for prime factorization of k would make more sense

flint wing
#

uh do we need it if we're just looking at preimage?

spark folio
#

well, you did factorize k=6 as 2*3 and thats how you got the preimages no?

#

you put n=2 for one case, and n=3 for the other

#

and ofc n=1 and n=6 too

#

what are 1,2,3,6 if not the factors of k

spark folio
#

yea, so same way, you are gonna need the factors of k for any of its values so that you can write $2^k = (2^{a})^b$ and thats gonna get you $m = 2^a$ and $n=b$ yielding the preimages as $(2^a,b)$ where $k=a \times b$

boreal girderBOT
#

Bacter14Fr0g

flint wing
#

ohh so (2^a, b) is our preimage

#

should we say b = k/a or it makes more sense to leave it as ab = k

spark folio
#

either way is fine

#

both statements mean the same thing anyway

flint wing
#

i see and if i needed to write a sentence about like the factors of k what should i say

spark folio
#

you can just write that the preimages depend on the factors of k, and that each of the distinct factor gives rise to a distinct preimage

#

and that trivially, since k = 1*k, you will always have at least two different pre-images for all k>1

flint wing
#

ohhhhh okay i think i get it now

#

thank you

spark folio
#

np

flint wing
#

.solved

compact pewterBOT
#
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compact pewterBOT
#
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remote garden
#

Can someone please help me with this question

remote garden
#

I just have no idea how to even start

kind viper
#

This physics video tutorial provides a basic introduction of standing waves in organ pipes. it covers the closed tube air column which is open at one end and the open tube air column which is open at both ends. The first problem explains how to calculate the fundamental frequency of an organ pipe open at both ends / open tube, the frequency of...

▶ Play video
ionic python
#

!nosols

compact pewterBOT
#

As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.

ionic python
#

and this looks like ai...

#

!nogpt

compact pewterBOT
#

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

ionic python
#

pretty sure no one will type latex without dollar signs

#

and not correct it

kind viper
#

<@&268886789983436800> AI answer

ionic python
#

and no one will add so many empty lines

kind viper
#

OP seems to be away

ionic python
#

probably watching tutorial

#

yep deleted

remote garden
remote garden
ionic python
remote garden
#

ya

#

good thing i didnt see it lol

#

.close

compact pewterBOT
#
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compact pewterBOT
#
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quartz yoke
compact pewterBOT
quartz yoke
#

,rccw

boreal girderBOT
quartz yoke
#
  1. ii. and iii.
#

I dont know what to do

potent berry
#

ah yes 10th grade ncert

#

@compact olive do you wanna join here

#

mujhe maggi banani thi KEK

cursive harbor
#

This is just basic conditional probability stuff right

potent berry
#

yes

#

12th grade ncert actually

compact olive
#

I wouldn't be the best at probability and PnC

#

Trust

urban kindle
#

oh these are fun! i have a deck of 52 questions

cursive harbor
#

Draw one

compact olive
#

In your own channel, diva

potent berry
#

we drew this

#

where is op

#

@quartz yoke

quartz yoke
#

Ok so how do i solve

quartz yoke
potent berry
compact pewterBOT
# quartz yoke Ok so how do i solve
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
quartz yoke
#

1

urban kindle
#

what is the probability that the lost card is a king without taking out any cards

quartz yoke
#

1/13

urban kindle
#

explain that first

quartz yoke
#

Oh 1 min

#

There are 52 cards and 1 card is lost, the probability of lost card is a king

#

So its 1/13

urban kindle
#

how many kings are there in the 52 cards

quartz yoke
#

Am i right?

#

4

urban kindle
#

given that you take out one king how many kings are there in the remaining deck

#

and how many cards are left

quartz yoke
#

3 king and 51 cards

urban kindle
#

within that, what is the probability of a random card being king

quartz yoke
#

1/17

#

Thats it?

#

Oh

urban kindle
#

do you know how to do part iii now

quartz yoke
#

Les see

#

1/425?

#

😭😭

urban kindle
#

wait

#

how did you arrive there

quartz yoke
#

3/51 x 2/50

#

Removed 1 card just like b4

urban kindle
#

wait why multiply

quartz yoke
#

2 cards to be drawn without replacing

#

Cuz 2 cards are drawn

urban kindle
#

they're drawn but you don't care abt the probability of that

#

you're just told that they're both aces

quartz yoke
#

Yes 1 ace is lost

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We have 3 aces

#

Out of which 2 drawn are aces

urban kindle
#

how many aces do you have left after drawing 2, in the remainder of the entire deck including the lost card

quartz yoke
#

1

#

Since another is lost

#

2*

urban kindle
#

how many cards

quartz yoke
#

Including drawn + lost?

urban kindle
#

mhm

#

not drawn

#

everything not drawn

quartz yoke
#

51 excluding drawn

#

52 if no loss

#

First of all, i have a doubt in ii

#

How does probability of lost card being king relate to the kings after losing a card

quartz yoke
#

Like b4 losing it was 1/13

urban kindle
#

conditional probability - you're told that you remove a king from the cards

#

if the probability of losing any card was uniform before, it's still uniform now, except you take out a king

quartz yoke
#

Elaborate further please !

west fern
#

thats calss 8th ques guys

quartz yoke
#

Could u please explain me even further 😭

urban kindle
#

consider the probability of losing any specific card, 1/52 at first

quartz yoke
#

Yess

urban kindle
#

after removing a king, that's 1/51 in the remaining cards

quartz yoke
#

1 or 3?

urban kindle
#

any specific card

quartz yoke
#

Ok

urban kindle
#

(because you did not lose the king that you removed)

#

there are 3 kings left

#

3*1/51 = 3/51 = 1/17

quartz yoke
#

Oh

urban kindle
#

the same with the 2 aces

#

you take out 2 aces—how many cards do you have left?

quartz yoke
#

50

urban kindle
#

how many aces remain

quartz yoke
#

1

urban kindle
#

there are 4 at first

quartz yoke
#

Then 2

urban kindle
#

2/50=1/25

#

do you get this

quartz yoke
#

Uhh

#

To some extent

urban kindle
#

don't consider losing a card until you have to calculate the probability

quartz yoke
#

Probability of which

#

The 2 drawn ace?

urban kindle
#

you're asked to calculate probability of lost card being an ace

quartz yoke
#

Ye

urban kindle
#

don't care about the drawn ace probability

quartz yoke
#

Then how do i proceed

urban kindle
#

you're not being asked to calculate the probability of drawing two aces

#

you take out two aces from the deck and want to find probability of the lost card also being an ace

safe kelp
#

In the bag of 5 red and 6 black ball whats chances of drowing the 2 red

cursive harbor
urban kindle
quartz yoke
#

5/11x 4/10 without replacing

quartz yoke
#

I forgot the total

urban kindle
# quartz yoke 😭

you want a probability on the lost card, not what you take out from the deck

quartz yoke
#

So could explain like how did u for ii

#

And tell what to take into consideration 1st and what not to

urban kindle
safe kelp
#

No perhapsp(r) =5c2/11c3

urban kindle
cursive harbor
#

Arpit please get your own help channel

quartz yoke
#

Without removing we have 1/13 chance

#

After drawing 2 aces the cards are 50

#

Then the probability of ace being lost from 50 cards?

#

Or probability of ace being lost after 1 ace is removed then 2 cards are drawn

#

Which are also ace

urban kindle
quartz yoke
#

Then caluclate lost ace?

urban kindle
#

calculate P(lost card being an ace | deck of 2 aces in 50 cards)

quartz yoke
#

1/25 simply

urban kindle
#

yea!