#help-4
1 messages · Page 19 of 1
In e^iπ.... Or in cos + i sin
Which is easier for simplifying into a real function like the expansion of sum
its more intuitive to write e^{i pi} and use exponent laws imo
if you don't want to leave it as eta_k for some reason
Ok thanks
actually
But like result is supposed to be real
if you want to look for relationships to get rid of i appearing
you should consider conjugates
because
So somehow ak/-24 times ln(x-ak) + the conjacutive should be real
z+z* is real for all compex z
Yes but thing is
The conjacutives have different factors
But im guessing they are just opposite
So should be good
Yes
like ak/-24 should be matching with ak overline /-24
so put them back inside
Ok so i write it in e^iπ form
Can i somehow match Pairs before expanding sum?
Like sum 0 to 11 ak/-24 ln(x-ak) + ak* /-24 ln(x-ak*) prob
This correct ?
oh i thought you wanted to try combining them before integration
Oh no
Thats much more effor
Trig sub needed
I just use complex ln
But i think its better with csc with eulers trig identity
Instead of e^i..
That way i have both directions
@worn sparrow this correct ?
yeah but this can probably be simplified too
no
$z+z*=2\Re{z}$
gfauxpas
my cat is trying to get my attention by blocking my pc one moment
no because
If you dont integrate you'll get integrals of the type Ax+B/Cx^2+Dx+E
Needs square completing and trig sub
btw you don't want to write "ln" here. Or at least I wouldnt
there's more than one convention, but
you don't mean the principal branch of the real natural log
you mean any branch
but it' s not a big deal because it's all collected into the +C anyway
ln(x-ak) = ln|x-ak| + iarg(x-ak)
I wouldnt write that, I would wirte
ln(x-a_k) = log|x-a_k| + i arg(x-a_k) because otherwise ln means something different on the RHS and LHS
but then again there are different conventions about this
Log though you dont mention base
it's implied
Whats the diff
there's only one log worth mentionin as soon as you use complex numbers
because otherwise
ln means something different on the LHS and the RHS as I said
on the LHS it's a function of complex numbers, on the RHS it's a function of real numbers
"the" which one
it doesn't matter at the end of the day because it's implied by the +C but
there's nothing stopping you from choosing a different log for each factor
so nothing cancels out
alright nm, i 'll stop annoying you about it
Wdym
i'm asking you to figure out the answer on your own
the conjugate of a number a+bi is the number a-bi, for real a,b
Well id just consider the function with cosx -i sinx equal to e^-ix
And proce its true
Ok so it is this
i didnt want to hand the answer to you, i wanted you to figure it out
yes
for |z|=1
Whats the command?
,rccw
You see anything i can do
I can factor out cos and have multiplication of ln but cant really do none with that
Yes
honmestly it's hard for me to think about that many terms at once
but trig identities about supplementary and complementary angles might be relevant
Great idea
I gtg do some ill check trig swaps later
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can i take the 2^2x as 4^x ?
sure
that looks horrendous
are you trying to simplify it?
sin cos^-1 can be simplified
consider a triangle 👀
I'd prolly start with that
draw out a triangle
yup
and think about what the cosine function is in terms of the triangle

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This problem is giving me trouble. It asks specifically for an induction proof; but when going about it, I encounter a term that I can't get rid of
do you recognize that this term is positive
Yes
apply that to your last line and this goal should be immediate
I'm not following. How does that help?
you see this right?
do you see how it differs from the right side from the goal?
Yes, it differs by that ka^(k-1)h² term
I also just noticed I'm missing an exponent of k for the kah term
do you see why if x >= y + z and z > 0, then x >= y?
No
try adding y to both sides of z > 0
Okay, I've got y + z > y then, where does the equals come from?
combine what you got with x >= y + z
Right, that gave me x >= y + z > y
and u > v implies u >= v
Right, because of inclusive or
Forgot about that
Thank you. I found where the missing exponent went and it worked out!
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can yyou guys help me make a word problem
for?
so you just need to make a word problem that can be modeled and solved using a quadratic equation
projectile motion problems usually involve quadratics
i got an idea but i think thats a cool project for you to think about!
can we even give any hints that would not amount to doing the problem for op
no im just bad at logic based things 😢 like what would be an activity or somethign that would result in a quadratic
uh
visualization
projectile motion
i mean
since its a creativity based project i think that it can be pretty satisfying if you come with an idea
whats focii
no
oh nvm then
@silk peak Has your question been resolved?
@silk peak one class of easy real world problems involving quadratics are anything involving tracking the position of accelerating objects.
how
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Hello! I'm taking my TEAS exam, and I need help with visualization on certain geometric shapes. In this problem, I already know the answer, but I guessed instead of sketching it out, and I REALLY want to be able to visualize it properly. Is it possible for someone to sketch a quick diagram of the problem and what they mean by "the perpendicular distance between the pair of opposite sides"?
well wudnt the perpendicular from left to right be 45?
i originslly drew that out too, but dont see how L>R wud be 40.5
its not perpendicular so no
the 30cm and 45cm sides arent perpendicular to one another
My random ass guess was that I should divide the area by the other number. I don't even have a good explanation as to why, it was a random dice roll.
cant read
oh is this the ultimate server for overlyintellectuals
Its just that the formula for area of parallelogram is base x height
so you can take any of the two bases/heights
i have no idea how to draw this tho
and therefore you should have that 30cm x height = area
therefore the height is area/30
:)
Welcome 
So maybe I don't understand parallelograms as well, because I'm a little confused as to how 30cm counts as a base...
thank you!
pleased to be here
any side can be the base
all sides can count as a base, and then the height is the distance to the other side
get it?
Let me see if I can sketch this
i can on paint if you want
holdon
might not be pretty
either multiply the two reds, or the two greens to get the area either way
yeah thats what I thought
👍
They wanted that green length
yup
That is so vaguely worded though. Ugh
I hate the TEAS exam.
Thanks for the help everyone!
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I'm planning on returning to uni this fall to finish my engineering degree which is basically just all 4 years anyway... I have been going from very early math up to uni and still have a while to go. However, I haven't been getting enough just algebraic manipulation practice and I know how important that is. Are there any compilations that just lay out all of the manipulation rules/properties in an easy to understand way ? If so that would be great
a lot of the implied things like a negative exponent is just a reciprocal so in exponential decay when your common ratio is 1/2 and you go backwards with a negative exponent I understand how that makes sense in that you're now dividing by 1/2. There are a lot of little things like that I forget though, does anyone know what I mean?
khan academy maybe
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not sure if i did the calculations here correctly
mhm, that seems right, but make sure you phrase that correctly: it's p(x) when x=0 and x=1

ohh ok ok thank you!!
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it is a different question for the homework, do i have to make a new channel?
-# I'm not sure about this one sorry 
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I went with this question because
0.3 - 0.5 = 0.20
then the standard dev is 0.0707 so
i divided 0.20 / 0.0707 which got me 2.83
oh sorry I hadn't sent the full question yet
!original
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thats the original
might be because this question has multiple parts
we can see that by the phrase "larger bag of skittles"
this screenshot is the entire question sorry
this is a part of a bigger problem, and it's not the first part. We need the parts before
by that I meant the question with the options
there isnt any other parts
From the answers provided, it is sensible to assume there are 5 colors, and the color picked for a specific skittle fits a discrete uniform distribution
what comes immediately before of what you posted?
this question
this one i already got it tho
are there any questions before this one that mention skittles?
nope
hmm
we are just supposed to make an assumption
apparently skittles bags have 5 flavours
i guess they just force you to assume what the fuck is in a skittles bag
It is implicitly stated in the possible answers that we assume the expected amount of green skittles is 20% of the total. So we have that p = 0.20.
and you also have explicitly that you have 100 skittles in the bag
so n=100
so... run the simulator with that? i guess?
that's... not the value of p that you're supposed to use
Then remember to use the provided value for p̂
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Okay, so I know what to do once I have the magnetic field vector
But I don't know how to get the magnetic field vector...
the equation I know just gives me the magnitude, but I need the direction as well
This is the equation I have, but it gives a scalar quantity
The direction can be found based on whether your currents are parallel or antiparellel
How so?
oh wait. Sorry I'm thinking force
😭
For direction of B, use right-hand rule
outta da page, then?
I'm lost on what happens, though
Because I know that
$\int\frac{Lsin90}{r}$
Blake
How does that become what that equation simpliefies to?
I think it's into the page, actually
How do I know the direction of the L vector?
It's the same direction of your current flow
Mm
That seems arbitrary
But intuitive
It's 9:30, let's go with it :)
@neat locust What's the angle between B and the vertical and horizontal wires in the rectangle?
I'm pretty sure the vertical are 90
I'm confused about the horizontal, though
parallel would be 0, and antiparallel would be 180
So B is into the page
and the horizontal run in the x axis
I don't see how they're either parallel or antiparallel lol
Oh, wait
B for I_1, yeah that's what I'm getting
Would they be 90?
Surely they're not both 90, though...
Well, why couldn't they, I guess
90 with what
between the horizontal wires in the rectangle and the magnetic field
Oh. Yes.
all the wires are 90 with B?
And if you don't mind, could you tell me if it's accurate to say that the magnetic field is greater at point B because the two wires add together for point B, but subtract (because the magnetic fields are in opposite directions) for point A?
Is this an entirely different question?
:D
Well, I did say "if you don't mind"
feel free to abandon me
and make be completely fail summer school, and live under a bridge because I couldn't get my degree
btw yes this is a loose way of saying the correct answer
I tried to do the right hand rule, but it seemed like for both points the wires contributed a magnetic field in the same direction
You may want to mention which direction the magnetic field is going
At point B, the magnetic field is out of the page, due to wire 1
Break it down case-by-case
I1 on A
I1 on B
I2 on A
I2 on B
Which directions are the magentic fields going in each case?
wire-to-point
I1 on A is into the page?
Now I2 on B
I'm thrown off, it seems like it's out of the page
Which lines up...
You're saying I2 on B is out of page?
So I1 on A, then is into the page
that's what I thought...
You are correct
okay
So the magnetic fields on B add
I1 on A is into the page
and I2 is out
so they subtract
okay
Then do the math for part b, then use some equation for torque for the explanation in part c
Thank you @neat locust
Have a good night my friend
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@neat locust I have another question :D
So, what distance, r, do I use for the vertical lines? It changes as you go along the line
(please don't say integration)
this is why you need a line integral 🙂
😭
We don't have equations with any integrals for force, only for magnetic fields
F = IL X B
Force would be the same thing
$F = I B sin \theta \int dL$
Blake
Please tell me that's right, that would be so easy
$\vec{F}=\int I\dd\vec{L}\times\vec{B}$
SWR
I is constant, take that out
dL cross B is dL times B times sin theta
oh wait, is B not constant?
it would depend
on distance
B and L are functions of distance, yes
So what happens to our integral?
It depends on the exact problem
the distance from the long wire to the top of the rectangle is 7cm
So the distance for B is dL + 7cm?
$\vec{F}=\frac{uI}{2\pi}\int I\dd\vec{L}\times\frac{1}{R}$
Blake
$\vec{F}=\frac{uI^2}{2\pi}\int \dd\vec{L}\times\frac{1}{\dd\vec{L}+.07}$
Blake
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what the heck is happening here
I don't know, I tried...
I'm not good at integrating in physics
Calculus belongs in calculus 😭
Not in Calc based physics
calculus was invented for physics 
And this course is called "Calculus-based physics"
life was simpler when we lived in huts
who cared about velocity? Farm, raise children, die, day of judgment, resurrection
Okay. First, what question are you trying to answer? You;ve been asking a few and I don't know where you are exactly
So, I'm back on the first one
I thought I was cooking with gas
then I realized I didn't know what distance to use for the vertical wires
Horizontal are easy, I've got R, I've got L and I, no problem
the R and L varies for the vertical, though
@south sorrel Has your question been resolved?
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help
I need someone to walk over this quesiton with me, its simple but i dont get it:
You won't need kirchoff
Calculate the equivalent resistance
I think, you already know how to do that, by looking at the ckt. From the back, or as they say.
I'm not too sure, i went from coulombs law to this in a weel and have an my first exam tmr(today) i'm more lost than u think
cooked ggs
Yes
do you know how to calculate equivalnt resistence
alr look at 4r and 2r
for series u add them for parallel u do ^-1
arent they in series
so can you replace them with one single resister?
oh wait, so u add them, and than do parallel with the 3R right? and then after solve that by adding the regular R?
yes
omg
thats just for total equivalent resistance by the way
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0.2 A is not total current
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what does this imply?
Did you check your answer with the key
kirchoff rules are required
how do I apply that?
the junction tule and the loop rule?
I think youll need only the current sum rule
IN current sum = OUT current sum
into a junction
yea I remember, but how will that be applied here? after summing the resistance?
At the junction between R , 6R and 3R the current splits
In going current is total current
Current going through 3R is given
Draw the circuit keeping everything the same except the 2 resistors in series combine them to 6R
yea
alr now theres a junction between the resistors labelled R, 3R and 6R right
so the original current will be 18V/R hat split to I for 3r and 6r right?
but then how do u solve for current three going to 6R?
The resistance of 6R s double that of 3R right
So half the current flowing through 3R will flow through 6R
do you want a different approach
lowkey
You knw abput voltage law?
not too sure
or do you wanna continue with current approach
IG stick with the current one
Alr so current passing through 3R is 0.2 right
so the other half is 0.2 as well going 6R?
No
oh ok.....
The same current doesnt go to both
Because it is "tougher" to go through 6R than 3R
How much more "tough" is it to go through 6R compared to 3R?
So current through 6R will be half of current flowing through 3R right
so its 0.1
so total current?
so 0.3
so R will be 60, 18/0.3
You can verify this using voltage rule
so just voltage of each right and add them up?
yes but choose the loop properly
You can use the voltage rule alone to get to the solution also
dang
yea I did get 18V by adding R and 2R after parallel
that made akot more sense, thanks for the enlightment, gotta go before i get no sleep
preciated
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How do you solve xlnx = 2i(pi)
aln(b) = ln(b^a)
ln(x^x) = 2ipi
x^x = e^(2i*pi)
Try from here ig
Idk about solutions in C tho
Ig some branch of lambert W
Idk
e^(2i*pi) is 1
Yes
that was the original problem
i put the ln of both sides
because idk i thought it would be easier
Ah so you are going in the wrong direction
but idk how to use lambert w
wait so like
what do i do then
Let u = ln(x)
I mean yes you are going right but need one correction
To make it appear
I mean the original question is x^x = 1
I think
oh
He didnt include the n multiple after taking log
so we are solving x^x = 1 in C?
I think so
Otherwise it would be trivial ig
x^x = 1
Take log
xlog(x) = 2n(pi)*i
And use lambert W ig
Its the inverse function of f(u) = ue^u
yeah i made it up like an hour ago 😭
I wanted to find complex solutions to this
not real ones
its quite obvious what the real solution is
do we need to
Yes
I wanted to just assume n = 1
Then you'll find a very specific solution
like i wanted to find the smallest complex solution too
exactly
i wanted to find the solution in the form x + yi
There is no ordering in complex numbers
There is no "smallest" complex number
what about the modulus of the complex number
can't that technically be considered the "size"
I'm not sure if n=1 will yield the smallest magnitude
ah
what will then
well could we even know
Not sure how to check tbh but my guess is as n goes to infinity
The value will be smallest
oh
nvm then
ig i just want
a specific solution
Ohk
so like how do i use lambert w again
Ig using different branches of lambert W, there'll still be infinite solutions to your problem
yeah ofc
but lets just say i set n = 1
then it wouldnt be infinite
It gives complex values too?
blue is Im((x+yi)^(x+yi)) = 0 and red it Re((x+yi)^(x+yi)) = 1
yeah it gives everything
bruh this pattern is cool
but im guessing the biggest value that gives x^x = 1 goes to infinity?
yeah, seems like it
hmmm
goes to infinity in magnitude
i wonder what im gonna say as a solution to this tbh
i feel picking any complex solution would feel super random
Well you made the question yourself
Pick 0 
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basically
you have these equations and u need to find the minimal value of 100x+10y+z
my question is
it says in the solution in the picture:"from the asumption 96=xy+yz+zx>=3x^2 where did we get this from?
<@&286206848099549185>
o yeah and x,y,z are natural numbers
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given the equations and x,y,z are natural numbers,find the minimum value of 100x+10y+z
solution:we can see that the equations are simetrical,without the loss of generality we can assume x<=y<=z
from the first equation ....=1680 <=>(96+x^2)(y+z)=1680
from the asumption we have 96=xy+yz+zx>=3x^2
Alexis_Fx
my question is where do we hey the last inequality from(the one with the 96(on the bottom))
When $x=y=z$ we have $xy+yz+zx = 3x^2$
Alexis_Fx
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I’m so mad
I’m so mad
A (1,0,0)
B(0,2,0)
Now project it into xy plane and tell me the equation
People
Find the normal first
It is (2,1)
No problem
the normal to what
So the line can be written as 2x+y=r
r is 2
Is it how it is done
Please Mickey lord
Tell me
Any shortcut
Please
Mickey lord
Should I say Mickey lord or lord Mickey
!original
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what was that
That pmo
lol
bro went on a schizo rant
Fr
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How do I know whether my LU factorisation is correct?
There are really many answers depending on how I go about my Gaussian elimination... correct?
How do I check if it's correct? The answer key has a different L
LU = A, you can check your work simply by doing the multiplication.
,w {{1, 0, 0}, {2, 1, 0}, {2, -2, 1}} . {{1, 1, 2, 4}, {0, -2, -3, -7}, {0, 0, -6, -11}}
Looks like you made an arithmetic mistake at some point, the last row is incorrect.
It's can't be multiplied tho....3x4 with 3x3
3x3 with 3x4 can be
AB is not equal to BA for matrices
The answer
In this case LU exists and is a 3×4 matrix. UL does not exist because of the incompatibility of the dimensions
Ahhh my bad I saw wrongly
Mhmm
,w {{1, 0, 0},{2,1,0},{0,0,1}}.{{1,0,0},{0,1,0},{2,0,1}}
,w {{1,0,0},{2,1,0},{2,0,1}}.{{1,0,0},{0,1,0},{0,-2,1}}
I see
I'll double check!
The error would need to be in the last row of the L matrix
And you performed the matrix multiplication correctly, which implies that perhaps the issue is with turning your row operations into matrix values.
Is there any way to find L without multiplying 3 matrices?
I feel that it's ripe for arithmetic errors
I found the error, but the answer is still incorrect
Hmmm
If you can find a way to make an upper triangle matrix with fewer row operations then you need to do fewer matrix multiplications.
Wait is it definitely an error with L?
I know the middle 1 should be -1 instead
But the output is stil wrong
Well, that's the most likely cause of just the last row of the product being incorrect
Here
I've checked multiple times but I can't spot the error
O.o
Strange
Ah i multiplied the matrices in the wrong order
For L
It shld start from the right
,w {{1, 0, 0},{0,1,0},{0,-2,1}}.{{1,0,0},{0,1,0},{2,0,1}}.{{1, 0, 0},{2,1,0},{0,0,1}}.
I don't think that's correct either
Bottom left entry must be a 4
,w matrix inverse {{1, 0, 0},{2,1,0},{0,0,1}}
Your three row operations seem to have been done correctly.
,w {{1,0,0},{-2,1,0},{0,0,1}}.{{1,1,2,4},{2,0,1,1},{4,4,2,5}}
,w {{1,0,0},{0,1,0},{0,-2,1}}.{{1,1,2,4},{2,0,1,1},{4,4,2,5}}
,w {{1,0,0},{-2,1,0},{0,0,1}}.{{1,0,0},{0,1,0},{0,-2,1}}.{{1,1,2,4},{2,0,1,1},{4,4,2,5}}
,w {{1,0,0},{0,1,0},{0,2,1}}.{{1,0,0},{-2,1,0},{0,0,1}}.{{1,0,0},{0,1,0},{0,-2,1}}.{{1,1,2,4},{2,0,1,1},{4,4,2,5}}
@devout holly you had your row operations wrong
,w {{1,0,0},{0,1,0},{0,2,1}}.{{1,0,0},{2,1,0},{0,0,1}}.{{1,0,0},{0,1,0},{0,-2,1}}
That should be your L matrix
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or its a complex analysis q. in which case byeeeee
You can do what you want, all you need is an upper bound
Might be useful to consider z = 2e^(ix)
it's complex analysis
what is maximum modulus principle again i forgot everything abt cmplex numbers
This is on the boundary so not helpful
It says a holomorphic fucntion attains max at boundary
im generally not any helpful if it concerns complex numbers lol
all you need is to use triangle inequality, like always in these problems
Once you have factored like this
complex analysis
🥀
What’s the fuzz about saying complex analysis
should be |z^2 - 2||z^2 - 3|
It’s easier than real analysis, and very elegant 
it can be also factorised to |z^2 -3||z^2-2|
that's what i wrote two messages above
no it isnt lol
No way
His factorization was false
yes this
mine was z^4. -5z^2 - 6 🥀
shi
I took complex analysis before real analysis 
You can't factorise two ways
you have a messed up syllabus
can yall discuss your preferences in math elsewhere so we can help aditya with his problem please??
I made the choice
thank you
One is right and other is wrong
stop clogging the channel plz
her? 💀
seriously, residue theorem is easier than heine borel bro???
You think aditya is a girl???
what are u? "it"?
maybe
ok jokes apart
consider a geometrical approach
.
at least, i guess
No you dont need all that
thats my first sentence
triangle inequality
it didn't i am getting multiple answers
there are multiple
Oh it says find an upper bound lmao
there's an infinite amount of upper bounds that work
if x works, x+1 too
so if you find something, its enough
no , it has to be single answer. according to book (it seems)
might be the best answer they are asking for then
Then the question is ill formed
Yeah
maybe i tis the least upper bound?
Unless the upper bound is infty lmao
yeah, the best one
just use triangle inequality you should get single upper bound
i used inequality but there's more to it, it seems
i am getting 1/2, 1/10, 1 and infinity
i need to eat food, i'll be back. hopefully someone finds a solution
just use |z^4-5z^2+6| <= |z^4|+|5z^2|+6
|z^2 - 3||z^2 - 2| <= (|z^2| + 3)(|z^2| + 2) = |z^2|^2 + 5|z^2| + 6 <= 16 + 20 + 6 = 32, right?
I think that will give lower bound instead of upper for the reciprocal
that gives u the least upper bound
oh right
🤔
upper bound of
[ \frac{1}{|z^4 - 5z^2 + 6|} = \frac{1}{|z^2 - 3|}\frac{1}{|z^2 - 2|}]?
nahh
k
also didnt notice
|z^4-5z^2+6| >= min( | ±|z^4|±|5z^2|±6 |)
now i understand your issue
in this case you can use any combinations of signs, but you need to understand that value that you will get is bound but not necessary is exact
nvm what i wote above seems incorrect
@quiet ledge Has your question been resolved?
upper bound means maxima?
we can
|z^2-3| >= |z^2|-3 = 1
|z^2-2| >= |z^2|-2 = 2
ensuring that we have eq on z=2
|z^4 - 5z^2 + 6| >= 2 with eq on z=2
I don't think so. It is supposed to be limited by triangle inequalities
Oh, hmm this looks good.. uhh lemme check
Idk why I got 49
upper bound indeed maxima but we need find it for reciprocal so we actually looking for minima of |z^4-5z^2+6|
so answer is 1/2?
okay okay umm
yeah that's good
but uh
|z^4-5z^2+6| >= ||z^4| - |5z^2-6||
14 <=|5z^2 - 6|<= 26
i get
|z^4-5z^2+6| >= 2 and/or idk |z^4-5z^2+6| >= 10
that means answer is 1/10 or 1/2
also if take 14 <=|5z^2 - 6|<= 26 = 16 then answer is 1/0 = infinity
@orchid otter
here you need to avoid applying
|5z^2 - 6| = some value, because of that you fixed z value
you can think about it in this way with |5z^2 - 6| =16 you get
|z^4-5z^2+6| >= 0 but so 0 is lower bound but not necessary exact lower bound
also when |5z^2 - 6| = 26
|z^4-5z^2+6| >= 10, but not necessary exact lower bound and in this case
its only for z values that |5z^2 - 6| = 26 (z^2=-4 for example)
because of similar thing we ensure that we have z that makes eq both here, so this is exact bound
i don't think i have fixing z with |5z^2-6| = 16 because, z is two variable x,y .
anyways, 16 is a possible value.
14 <=|5z^2 - 6|<= 26 this thing stands true for anything. right.. so
uhh idk
i think answer is either 1/10 or inf
okay lets say we have person that walk on stairs from 1st floor to second
his head always above his feet H_h > H_f
but we know that his feet somewhere between 1st and 2nd floor
this doesnt mean that his head is always above 2nd floor
do u mean "this doesnt mean that his head is always between 1st and 2nd floor"
i mean if H_h > H_f and 1st_floor<H_f<2nd_floor
this doesnt mean that H_h>2nd_floor always true
his head can never be less than 1st floor as long as 1=<H_f<=2
H_h can be >= 2 if 1=<H_f<=2 (let's say 1.7)
hmm
i can't see how this anology applies to our problem.
it can be >=2 but you cant say that its always >=2
so when |5z^2 - 6| = 26 you get |z^4-5z^2+6| >= 10 but its not for all z
ok so you are saying is, we don't know value of |5z2 - 6|. we only know its whereabouts
but for all z , |5z^2 - 6| must lie between 14 and 26 right?
|z^4-5z^2+6| >= ||z^4| - |5z^2-6||
14 <=|5z^2 - 6|<= 26
correctly say |z^4-5z^2+6| >= ||z^4| - T|
for any z this is correct for some T in range [14, 26]
but not necessery for any in that range
but that means 14 <=|5z^2 - 6|<= 26 is not true inequality?
its true you just cant apply it this way
returning back to analogy
1<=H_f<=2 is value with known interval
and H_h > H_f
its incorrectly to say that H_h>2 always
look at this, they did nested inequalities. but i don't understand
one thing i understand is. they took 5z-1 = 11 because 11 is closer to 16 to make denominator smallest possible
We haven't already done this exercise together a few days ago 🧐
Oh ok not the Same
Almost xd
actually, 1+H_f<= H_h <=2+H_f
in this case it worked only because |z^4| > |5z-1| so to minimize
|z^4| - |5z-1| we maximize |5z-1|
yes you can see that H_h and H_f are related
in other words not any H_h(t1)>H_f(t2) where t1, t2 are different time moments
how do we know we need to maximize |5z-1| to minimize |z^4| - |5z-1|?
|z ^4| is exponential it will increase faster |5z-1| right? so
increasing |5z-1| will also increase |z^4| even greater ?
we got fixed |z|
basically this will work when you have one value that bigger than all others together, it will not work in problem with 5z^2
so to minimize ||z^4| - |5z-1|| we need |5z-1| closest to |z^4| = 16
so we had 9<=|5z-1| <=11 so we take 11 which is closer to 16
but what we can do when for example: 10<= ......<=20 ?
yes here it works, if we try to apply it in prev problem with 5z^2 we will be able to get 0 as lower bound but cant guarantee that its exact boud
yeah in this case you also get lower bound, but you at this point also dont know if its exact bound
so you need provide some z value to prove that its exact
this part i am not able to understand that "we dont know its exact bound"
because we have restrictions in this case z^4 and 5z^2-6 are not just any values with such modulo,they have relation
its not exactly the same but if you have sides with length 3, 5 the third side of triangle is bigger than 2, but lets say we have restriction, for example angle between 3 and 5 sides, lets say its like >=30 , then while triangular inequality says that third side >=2 but we cant get 2
Did you guys get the answer?
also if u factorise |z^2-3| = |z+3||z-3| and |z^2-2| = |z+2||z-2| we get |z^4 - 5z^2 + 6|>= (3-2)(3-2)(2-2)(2-2) = 0
u forgot sqr root
|z^4 - 5z^2 + 6|>=0 is not breaking anything
its correct lower bound just not exact
but we need exact
then how we know 1/2 is exact?
why sqr root?
z = 2
|z^2-3| = |z+sqrt(3)||z-sqrt(3)|
ohhhhh yeah my bad
we get eq with z = 2, you can also ensure that all ineq in process also become eq with z=2
yeah if you just calculate for this z you will get 1/2, this way we show that this is exact bound
in simple cases
problems with single inequality are usually simple with this
there is usually one point when ineq is eq
but when you use different ineq sometimes then become eq on different cases, in this case its become dirty
in case
|z^2-3| >= |z^2|-3 = 1
|z^2-2| >= |z^2|-2 = 2
ensuring that we have eq on z=2
we actually got lucky that they have same point of eq (actually its problem design but anyway)
wdym eq?
is this the question
yes
equality, so i meant z value when ineq reachs eq
thanks @orchid otter i am just getting headache thinking more about this.
i just want to be able to solve all kinds of problem. i wish i had question bank realated to triangle inequalities.
i still don't understand completely
its fine you just need to remember that if you get some boundary it could be correct but not exact
yeah just like -infinity to infinity correct for all real numbers and expressions but not exact for equations or set of equations and inequalities?
yeah, that why in such tasks we need provide values that will reach boundary that we got
only bad thing is you cant know if boundary is incorrect, you can know only if its correct if you find values to reach that boundary
hmmm, that makes sense
i wish we were taught some general method to solve this kind of stuff
anyways
thanks
thanks a lot
🫡
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why are my answers wrong
well for starters you put latin a instead of greek alpha everywhere
k
💔
but also i am p sure the third answer is wrong even post-correction, so double-check that!
vro how am I suppose to tell the difference if it is so tiny

please do not call me "bro"/"brother" or any variations thereof!
could you edit that word out, please?
I just say that to everyone lol
no matter who you are
also this was right
thanks
ngl this is a weak excuse
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how do you solve this without using newton's method or r alpha method (easier method) after getting sin(2x) + 2cos(2x) = -2
use pythagorean theorem then quadratic formula
oh
Why does the r alpha method not appeal
how exactly would you do that
seems the easiest
we weren't taught that method in class
does that mean you can't use it?
Country?
hello, this channel is occupied; for general discussion please see #360643390594875392. if you have a specific math question, see #❓how-to-get-help
well i used it anyway but i was hoping to find an easier version
I think r alpha is the most straightforward method
although I get that you want to see how it's done in class
