#help-49
1 messages · Page 58 of 1
that's merely a very simple counterexample
It is absolutely not a necessary condition
its not the unique condition ?
va falloir bosser tes compétences en logique car après 1 an de prépa, je sais pas comment t'en est encore là
t'es bien en sup dans une petite prépa?
oui je me débrouille bien en plus
oui
désolé mais je n'arrive pas à me l'imaginer quand je bute sur quelque chose j'ai l'impression juste quand je le code de toute façon je fais déjà une rotation
donc forcément elle existe
SL2(R) est naturellement isomorphe au groupe (R / (2piZ), +), lui même isomorphe à R / Z aussi connu comme S^1, le cercle
L'isomorphisme en question se base sur le fait qu'une rotation est définie par l'image de (1, 0)
Pour tout autre point, il existe un changement de base orthogonale (plus précisément la composée d'une homothétie et d'une rotation) qui l'envoie sur (1, 0). Donc une rotation est aussi définie par l'image d'un point fixé, en regardant où elle l'envoie sur le cercle du bon rayon.
Bref, une rotation centrée en l'origine est donc déterminée par l'image de n'importe quel point différent de 0, définissant ainsi une fonction f : R* x R -> SL2(R) U {pas de rotation} surjective
Il est alors naturel que pour une paire quelconque donnée, il est fort peu probable que f(x, x') = f(y, y') soit dans SL2(R)
Encore moins 3 points
le problème étant que quand je l'ai codé effectivement je connais tout les points avant la rotation forcément et j'applique une rotation d'angle theta aléatoire à ces points donc la rotation à déja bien lieu, le mieux serait alors plutot de prendre 3 points avant et après sachant que ceux après conservent la même distance par rapport à l'origine et les distances entre eux, il n'y aurait alors pas de rotation que quand il n'y a permutations de 2 points après
donc tu construits tes points de tel sorte que la rotation existe toujours
c'est le problème de mon programme je viens de me rendre compte
c'est pour cela que je ne comprenais pas
après construire des points de manière aléatoire de telle sorte qu'il existe une isométrie les envoyant comme tu veux, ça parait compliqué
faudrait juste que je dise ok je conserve les distance par rapport à l'origine et entre eux et voyons voir si une tel rotation existe
non si c'était vraiment aléatoire j'en aurais jamais des rotations
jusqu'à ce que tu te rappelle de ce que sont les isométries de R²
pas vu encore
c'est le dernier chapitre à voir cette année
ok
on conserve la norme dans les isométries ?
par définition tu préserve la distance
une isométrie directe
la notion de directe est arbitraire et inutile ici
ça conserve l'orientation de la figure si j'ai bien compris
donc c'est plutot à partir de 2 points ou plus qu'on a pas forcément rotation
pourquoi m'a t'il parlé de 3 points ou plus ? je n'en ai aucune idée
C'était ton idée ?
oui enfin c'est mon prof qui m'a dit qu'a partir de 3 point ou plus ça va poser des problèmes
je lui demanderai ce qu'il voulait dire par là
La question est bc plus intéressante si tu considères des rotations de centre quelque
c'est ce que je voulais faire au début, pourquoi donc ?
Car c'est soudainement plus trivial
mon prof m'a juste dit que je devait rester avec l'origine car $f : x \mapsto xe^{i\theta}$ était une app linéaire
Oui sinon 0 n'est plus fixe
phoestaclies
meme un isomorphisme ici
Mais les espaces affines c'est pas le diable
C'est juste hors programme
on en a parlé très vite fait oui
bon bah merci bien, j'éclaircirais tout ça demain avec mon prof. T'as fait prépa aussi alors ?
Comme tu le sais
À moins qu'on n'ai pas parlé depuis 1 an car j'ai changé de pseudo ici
tu as déjà une école, enfin tu es peut etre meme déja beaucoup plus loin que ça
nan je me rappelle pas de notre discussion
Non je finis la L3 là
juste de ton pseudo
LLG -> Ulm
c'était il y a deja longtemps je pense, après j'ai la mémoire courte pour certain trucs
tu était à llg et tu est allé à ulm c'est ça
bonne fin de soirée, merci encore
👍 je tacherais de ne pas oublier ce pseudo
.close
Closed by @pulsar sun
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
could somebody explain how the 4/log2x-2 3 becomes log3 2x-2
i dont understand how
2x-2log3 becomes 4log3/ 4log2x-2 right
look
do you know that log base a of b
is log b over a
@spice prairie
sorry im back
yes
so
so do you know change of base formula
alogb = clogb/cloga
this thing
oh yea
yeah
so it reciprocal so we flip
oh and thats log2x-2
so log(2x-2)/log3
/ log3
yeah
u get it now
and then 3log3 is just 1
yeahh
i have one more question tho
2sec
actually 2 more steps that i dont understand
first this
why does the above become that
and then just this
yes
so if you have lnx=2
for example
you exponentiate both sides with base e
to get x = e^2
doesnt it become e^lnx = e^2
one sec
😭sorry
lemme write it out
aight
😭
wait do you get it
a is the base
yeah
and also the base of the logarithm
its a to the power of log base a of b
aighttt i understand
its easiest to apply that rule
yeah
why does it become 1/4 tho
do you see that the expression is squared
out of the parentheses
yh
yh
@spice prairie Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
is the radius 8.9?
CAN SOMEONE HELP ME WITH 1+1
do you have it in the form (x-a)^2+(y-b)^2=r^2?
let's back up for a second. are you sure it's 16+64?
make sure you're accounting for the constant correctly
what i suggest is that your first step is to move the constant to the other side of the equation:
x^2+y^2-8x+16y = -16
yes
gj!
yep
looks right
submit and find out
that doesnt tel me if its right or not
you dont ever get feedback?
No
idk why she just doenst let us see our grade immediately
to stop cheatin gig
ig
but you see it at the end?
No
never?
it shows u after the due date
liek
if u submit
u can see after the thing is due
yes, so afterwards
i mean like
so its due at midnight tonight
i wouldnt be able to see it til it was midnight
that makes sense
yeh you have to
go to the form (x-a)^2+(y-b)^2=r^2
youve found a and b
now if you plug in the other point
you can find r
i have everything
honestly same
so friends cant tell each other the answer
exactly
where the questions r mainly diff for each person
i mean you can still ask friends for help
ah wait
nvm that wouldn't work
if the questions are diff then there is no point in hidiing the grade
if you know the answer is right, then you know (almost certainly) that the method is correct
hello, could anybody help me out with this question?: A store offers a one-day 10% discount on all cell phones. They also offer a warranty that costs either 5% of the discounted price or $35. Write an equation based on the original price that models each possibility for the warranty.
(sorry if this isn't how asking questions is supposed to work I can delete my message if so)
create your own channel under Math Help (Available)
ahh ok sorry i should have read that first
find an open channel and ask your question
@mighty pelican Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Consider the following subset of the XY plane $S={|z-iz|,|z|^2:z \text { is a complex number}}$
ƒ(Why am. I here)=I don't know
then which statment is correct
- S denotes an ellipse but not a circle
2)S is a parabola
- s is a circle
- S is a hyperbola
so $|z-iz|= |x+iy-i(x+iy)|$
ƒ(Why am. I here)=I don't know
ƒ(Why am. I here)=I don't know
can you give a geometric interpretation to |z - iz|
it feels like it should be a hyperbola
so z and iz are perpendiular to one another, right?
yes
no tell me what |z - iz| is first
this
z and iz are perpendicular of the same length
yes
I don't really know the equations of conics in $\C$
ƒ(Why am. I here)=I don't know
knowing this
you don't need to
this is all real stuff
z and iz are perpendicular and of the same length
what is |z - iz|
$\sqrt{2|z|}$
z is outside with a | |
ƒ(Why am. I here)=I don't know
ƒ(Why am. I here)=I don't know
so the x coordinate is just sqrt(2)|z|
and the y coordinate is |z|^2
i think at this point it's obvious what S is
a parabola
evidently
Closed by @twilit field
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
$let f \Q \rightarrow \Q$ be a function such that $f(x+y)=f(x)+f(y)$
ƒ(Why am. I here)=I don't know
where $x,y\in Q$
ƒ(Why am. I here)=I don't know

f(2)=f(1)+f(1)...
(this function happens to be Q-linear)
no idea what that means
this is supposed to be solved using HS level knowledge
yeah
don't
Define $x$ as a ratio of two integers $x=\frac{p}{q}$
it's derivative will be constant
SWR
it's not linear if it's a map from R -> R
consider what you can do with that
it might not be continuous
so this proves it's increasing on $[1, \infty)$( can be shown by induction)
what
ƒ(Why am. I here)=I don't know
SWR
can I present my method first please
Then prove $f(\frac{x}{n})=\frac{1}{n}f(x)$
SWR
sure
ƒ(Why am. I here)=I don't know
this proves f(0)=0
and similarly I can show It's odd about 0
so this can be extended to prove surjectivity

none of these yield an x such that f(x) = 5
f(3) is 30 for example
(which you CAN get from what you said, i agree, but surjectivity won't come from that)
for instance for $\Q^+$
ƒ(Why am. I here)=I don't know
$f\left(n\right)=\sum_{i=1}^nnf\left(1\right)$
ƒ(Why am. I here)=I don't know
I'm not done
$f\left(1\right)=2f\left(\frac{1}{2}\right)=4f\left(\frac{1}{4}\right).....$
ƒ(Why am. I here)=I don't know
this isn't enought though
I agree
should probably just find a general formula for $f(n) , n\in Q$
ƒ(Why am. I here)=I don't know
any thoughts?
I'm thinking
any rational can be expressed as the sum of an integer and a rational number
I guess I use that?
Probably not the best route imo
Because then you're still left with a rational number between 0 and 1. It'll end up taking the same amount of effort to prove. It is wasteful.
hmmm
ƒ(Why am. I here)=I don't know
could I have a hint
$f\left(\frac{p}{q}\right)=f\left(\floor{\frac{p}{q}}\right)+f\left(\floor{\frac{p}{q}}-\frac{p}{q}\right)$
SWR
Sorry that's not a hint. I was just writing out your tex
Do this first
I mean this is still enough
enough what?
$f\left(\frac{p}{q}\right)=f\left(\left[\frac{p}{q}\right]\right)+f\left(\left[\frac{p}{q}\right]\right)-f\left(frac\left{\frac{p}{q}\right}\right)$
ƒ(Why am. I here)=I don't know
This is my hint for you btw.
ƒ(Why am. I here)=I don't know
No. You did it for x=1 only
$f\left(nx\right)=f\left(\frac{n}{2}x\right)+f\left(\frac{n}{2}x\right)=2f\left(\frac{n}{4}x\right)+2f\left(\frac{n}{4}x\right).....$
ƒ(Why am. I here)=I don't know
like this?
Not quite. No. You proved $f(nx)=2f\left(\frac{n}{2}x\right)$. I'm asking you to prove that $f(nx)=nf(x)$
SWR
then I'm not sure
Hint: You'll need induction
Okay, for starters, what is your base case?
f(1)
Our base case is to prove that $f(1x)=1f(x)$
SWR
yes
I'm huessing that doesn't take a lot of effort to prove
Yes. Exactly.
do f(1x)=f(x)=1f(x)
Yes. Perfect
Base case proven.
Now, for induction, what do we need to assume is true and what do we need to prove is true from that assumption?
exactly right
it's certainly not "trivially" true
Trivial-ish. You still need to use your given property of f
even if it is "trivially" true, you should be even more so able to write a proof
Does anyone know about groups? I'm just looking for more information, nothing more (if you know Spanish better, the truth is, English is difficult for me xd)
!occupied
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).
Alguien más ya está usando este canal de ayuda. Si necesita ayuda con una pregunta, abra su propio canal o hilo de ayuda (consulte #❓how-to-get-help para obtener instrucciones).
How did you get this?
Hint: $f((n+1)x)=f([nx]+[x])$
SWR
brackets 
this is pretty unfortunate notation, since a lot of people use [] for the floor function
SWR
Closed by @twilit field
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
I'm lost on part b. I tried plugging in 5 for x in the equation above.
Did you solve
.05 = (0.8409)^x
?
Because that will get you a different answer.
Closed by @flint rampart
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
How to solve this?
you sum up each element individually if I'm recalling the notation right
Alright wait
or type it out
,rotate
The notation here is Sigma btw
It's fine dw
you do it step wise
as in first j takes a value (subsequent sum of all is)
then j steps up by 1
I can't understand this fully
But what happens when j takes the value of 1 ?
so your final sum is like this (all iterations are wriiten as (i+j))
(j=1 nothing)
(j=2) = i =1
j=3 i =1 and i =2
j=4 ; i=1 i=2 and i=3
j=5 not possible
Oh
nothing i cant take values so no sum
Okay
Oh I see
Wait lemme try this
Do you know any other method?
Something that helps when the range is large
I struggle with these kind of problems too
mostly discrete summations use the nested loop method
the thing to do is just nest the summations
so you will get it as sums of sums
but if the value is large people generally arnt sadistic enough to make you do it by hand
What will i be there
it will be like this
(1+2) + (1+3) + (2+3) + (1+4) + (2+4) + (3+4)
thats it
notice the ranges of i and j
minimum is 1 and i can never be equal to j as its strictly less than)
Oh I see
This will be the final answer right
How do we do that tho like I know the identity but how do we do it in this particular question
Double Sigma?
yep
Won't it be multiplication here then
the inner sigma is done first then the outer sigma
youve done some basic coding?
Ohhhh
Nope ;-;
This was done yesterday in my math olympiad preparation class
ohk so basically it is always summation but the step up for the outer sigma will happen once when the entire case of the inner sigma is evaluated
so j will increase by 1 after summing all possible i values in the range
if you have i<j<k then its 3 sigmas deep
so k will increase once when all of J finishes which it turn steps once when all of i finishes
but the internal function always remains same
this is very important
i +j will be the same in both the sigmas then?
wait ill give you a sample question tell mw how you will solve it
Alr
same sigma
the condition is (2 <= i < j <= k < 10)
the function is (i+2j+k)
step 1 write down the ranges of each variable starting from the rightmost variable
k will be [j,10)
think again
it takes everything from 2 to 10
cuz j can even be 2
Ohhhh
the outermost variable has no issues
so you can blindly just put the exact range mentioned in the question
no comes the tricky part
try for j
I see
again no lower variable its 2 to k
the k is correct though
I see
basically the same reason works i can take values from 2
Wait I get it now it's cuz 2<= i
yep
Yea
now i's range?
2 to j
equal to j?
Perfect
now step 2
expand the summation into n seperate summations and add the previous results
innermost variable is ?
k?
check again
i + 2j +k?
Mb I'm dumb af ;-;
[
\sum_{1\leqslant i < j < 5} (i + j)
]
mid
I see
now simply just go summation by summation for each subsequent j and k value
again KEEPING THE FUNCTION THE SAME
the (i + 2j +k ) part
and you are set
This the main issue
Like
I have to go one variable at a time?
yea 😅
Wait lemme try to solve it
@sinful river I'm clueless ;-;
Do I use n(n+1)/2 or something
Isn't this just a nested for loop
Basically
raged summations are nested for loops
the problem comes when you dont know what a for loop is XD
Yea idk what this is ;-;
lessgo
Closed by @manic bison
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
so to start, I approximate sin(sin(kx)) as kx
so I get
$(kx+cos(x)+x)^{\frac{2}{x}}$
ƒ(Why am. I here)=I don't know
which is in the form $1^{\infty}$
ƒ(Why am. I here)=I don't know
so the limit is effectively
well cos x is essentially 1
$e^{\frac{2}{x}\left(kx+x^2+\cos\left(x\right)-1\right)}$

ƒ(Why am. I here)=I don't know
nah nah
the limit of this at 0
i'd rather try find a form of $\left(1+\frac{a}{n}\right)^n$
Frosst
hmm, but is this approximation valid
it's this + some o(x^2) terms or whatnot
which disapear in the limit
yeah
$e^{\frac{2}{x}\left(kx+x^2+1-\frac{x^2}{2}-1\right)}$
ƒ(Why am. I here)=I don't know
I just need the answer for now, have an exam in 2 weeks
I'll care about rigour later

nah i'd do something like at this stage, let y = 2/x
so k=3
then go $(1 + (k+1)x)^y$
Frosst
then x = 2/y
huh, okay
$\left(1 + \frac{2(k+1)}{y}\right)^y$
Frosst
take the limit you get $e^{2(k+1)}= e^6$
Frosst
because x goes to 0, 2/x goes to inf
so k=2
yes
Closed by @twilit field
Use .reopen if this was a mistake.
👍
sorry for not caring about the rigour atm
the answer is here tho
because you have e^6 as what you want to get to
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Hi! Does anyone know what N is?

beats me
i really can’t think of what that could be. do you have a statement of the intermediate value theorem somewhere?
Nothing with N in it 🥲
Closed by @undone pawn
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Could someone help me determine what approach I should use when solving this? ie. u substitution, integration by parts
I don't see that identity on my sheet, which one are you taking that from?
sin^2(x) + cos^2(x) = 1
ah ok
I split it like you said but I am not sure what to do about the denominator
split as in distribute
also this is wrong
I meant something like\ $\int \frac{(1- \cos^2(x)) \sin(x)}{\sqrt{\cos(x)}} \dd x = \int \frac{\sin(x)}{\sqrt{\cos(x)}} \dd x - \frac{\cos^2(x)\sin(x)}{\sqrt{\cos(x)}} \dd x$
ginny
integral of (ab) is not equal to (integral of a)(integral of b) in general
May I ask why the 'dx' gets placed next to both terms?
oh I guess it's just how you've written it
usually it is factored out: (a-b)dx
but you wrote it a(dx)-b(dx)
regardless, I am hitting a brick wall with the square root of cosx in the denominator
how about a u substitution to get rid of that then
@jovial birch Has your question been resolved?
.close
Closed by @jovial birch
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
suppose $log_a(b)+log_b(a)=c$the smallest integral value of c $\forall a,b >1$
ƒ(Why am. I here)=I don't know
so to start
$\frac{\ln\left(b\right)}{\ln\left(a\right)}+\frac{\ln\left(a\right)}{\ln\left(b\right)}$
ƒ(Why am. I here)=I don't know
AM>GM?
u are overcomplicating
ƒ(Why am. I here)=I don't know
you welcome
.close
Closed by @twilit field
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
how is it a quadratic
Try expanding the RHS
,w (n+2)(n+6)(n+20)
so you have $n^3=n^3+28n^2+172n+240$
ƒ(Why am. I here)=I don't know
Closed by @craggy yew
Use .reopen if this was a mistake.
.reopen
✅
how did 151/7 come
I don't know the context
notice how the equations are in the from $a^3=2+abc$
ƒ(Why am. I here)=I don't know
$b^3=6+abc$
ƒ(Why am. I here)=I don't know
and $c^3=20+abc$
ƒ(Why am. I here)=I don't know
do you follow so far?
...yes
continue
now we have $abc=n$
ƒ(Why am. I here)=I don't know
yes
so we solve for n, yes?
just explain me this part
now we have $a^3+b^3+c^3=28+3abc$
ƒ(Why am. I here)=I don't know
im confused
i just wanna know why is the answer 151/7(i think i might have explained my question in a dumb way before so sorry)
,w 28+3(-15/7)
@craggy yew does this make any sense
ohhh
yes
cool, good luck
someone recommended me this book which has american problems as practice sums so im usin it
also solve past putman problems IMO
?
google past putman papers
if i recall correctly isnt putman an undergrad math exam?
i think ill need to study wayy more to solve em cuz i just started oly prep and the only math knowledge i have is like 0.1% nt and 8-9th grade math
and school math is useless for olys anyways
hmm, ok
these were the kind of questions they asked in teh 50s
this in the 30s
still tough for me cuz i dunno calculus
but yeah, do calculus first
this might be sort of solvable for me
what was the first question of the first putman paper?
lol i cant even understand the question
@craggy yew Has your question been resolved?
Closed due to timeout
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
A uniform sphere of weight W and radius 5 cm is being held by a string as shown in the figure. The tension in the string will be
Why is it at vertical equilibrium and not at equlibrium on the side
like not in the direction of string?
cuz it's not moving?
if you mean translational equilibrium
i mean tbf there's equilibrium in all directions
work with what you please
yeah
how do you do it in the direction of string?
like if you take the component of W in the direction of string
W_s = Wcosx
T = Wcosx
but the answer is incorrect
Ah okay
It's not "incorrect" per se
thing is if you're balancing forces along the string then you need to consider the normal due to the wall as well
oh
but you won't be able to calculate that
right?
T = Wcosx + Nsinx
Yeah it's kind of hard to
Better to just balance the vertical
Might be able to do it with torque
Closed by @rare cloud
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
pls send help
i dont know how to read this in order
For all epsilon > 0, there is some N > 0 such that for all n in R, if N < n, then 1/n is less than epsilon.
I just don't see why must 1/n be less than epsilon
wait
so, if oyu choose $N=\frac{1}{\epsilon} \leftrightarrow \epsilon = \frac{1}{N} < \frac{1}{N}$
Flappie
can i pick N to be 1/e
yes
if epislon and N were swapped, then thats not allowed
why tho
they are both > 0
but epsilon is stated earlier, the terms after are allowed to be dependent on it
ic ic
so if I have for all in front of there exists, the variable for there exists can depend on the for all in front of it
if the statement was: $\exists N>0, \forall \epsilon, \forall n$ then $N$ is just some number
Flappie
or if you have something like: $\exists x,\exists y,\exists z$ then z is allowed to depend on x and y, yis allowed to depend on x, and x isnt allowed to depend on anything (unless something else was stated earlier)
Flappie
Closed by @gaunt nimbus
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
Hello! how to proof that this equation has only got solutions in real numbers when sin(omega) and sin(delta) are equal (didn't put /2 because sin is positive for all possible angles because they belong to first quarter)
𝚃𝚛𝚒𝚜𝚝𝚎
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
@pale ravine Has your question been resolved?
@pale ravine Has your question been resolved?
I've found only one solution which is close to the restriction which is pi/2. Are there 0 solutions if angles belong to (0; pi/2)?
hey its you xdd
yes and again with weird questions XD
btw $\omega$ and $\delta$ are supossed to /2?
clonesolopros
both angles and both half-angles are in the first quarter and both must be half-angles
let $a=2x, b=2y, c=2\omega, d=2\delta \implies$
$sin(a+b)cos(c)=cos(a-b)sin(d),$ where $a,b,c,d \in (0,\pi)$
clonesolopros
@pale ravine Has your question been resolved?
This seems false. If you choose x = y then you get delta = 2 arcsin(LHS). Your choice of x and y are not unique, so you will get solutions where omega does not equal delta.
But what will happen if x can’t be equal to y?
One counterexample is enough. x = y is simpler because the cos term on the RHS goes away.
I understand it. but what counterexample will there be in case if x cant be equal to y?
The same argument would probably work except now it's uglier and you have to check for the constraints.
You just need to prove that for some omega there is more than one choice of delta.
You gave me an idea and I tried to redraw graph in Desmos. What will be a solution here if we look at graph? Everything in this crossing area? Or another function that should cross this red line?
Nvm, I think I understood what I was missing in this task and probably fixed it. At least it looks like I've fixed. After your message, I wondered what I was missing out on. So I decided to draw a full graph, made some constrains also took some things from the exercise and probably got what I needed. Thanks!
.close
Closed by @pale ravine
Use .reopen if this was a mistake.
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
The table shows 3 values of x and their corresponding values of y, where y=f(x) +4 and f is a quadratic function. What is the y-coordinate of the y-intercept of the graph of y =f(x) in the xy-plane?
did you try to graph it?
do you know the standard formula for a quadratic?
And also told to put it in factored form then substitute from the values on the table
can you write it out please?
AX^2+bx+c
great, now what happens if you plug in the numbers that you are given?
I can't plug in the values
why not?
I don't know a b and c
you have x and y values
doesnt matter if you dont know a b and c
thats what we are solving for
you should get a system of equations
you have 3 equations
and 3 unknowns
that means you can solve for the unknowns
do you know how to do that?
so, if you plug in the first point, you get $21^2a+21b+c=-8$
Flappie
Okay
and for the second one $23^2a+23b+c=8$
Flappie
Okay
and then also the third one
Okay
you can solve this for a b and c
Okay
if you do that, then you have a b and c for you quadratic equation
Okay
Well I don't have a b and c 😅
I think you stopped at substituting the x and y values from the table
Sorry if there's a misunderstanding
😅😅
thats what you are solving
like i asked you at the start
what do you notice about these points
Okay, thank you.
😊🙏
I think I will close this ticket now 😅. Thank you sir 😊 @sweet wing
.close
Closed by @abstract aurora
Use .reopen if this was a mistake.
can i open a ticket?
Yes
so do i just send a question here?
Send your question here to claim the channel.
Remember:
• Ask your math question in a clear, concise manner.
• Show your work, and if possible, explain where you are stuck.
• After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!
Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.
ah🙏thx
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
i have finished 12i), i'm confused for the rest of the two parts. i have no idea at all on how to begin question 13, it looks horrific
oa is y = x(x+3)
ob is y = x - 1/4x^2
ab is y = x^2 - 6x + 9
coordinates would be at the point of intersection of the lines
no
doing that gets u the point of intersection which is 0,0 or point o
u want to find a and b
yes
@analog saddle Has your question been resolved?
got x = 2 and x = 3.6
do i sub it back into any equation to find y?
2 x values means 2 points of intersection or am I confusing myself?
right ok
how would i be able to work out the area under graph?
i know its integration but not sure nhow
@analog saddle Has your question been resolved?
@analog saddle Has your question been resolved?


