#help-38
1 messages · Page 197 of 1
Same thing to prove (f(x) - f(-x))/2 is odd
And now you got two functions, one even and one odd, and their sum is f(x)
U welcome
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hey can someone help explain pls
lim x+sin2x / tan3x
x -> 0
h?
did you mean x -> 0? @glacial garden
Oh yeah sorry!!
I'd try small angle approximations
so $\lim_{x \to 0} \frac{x + \sin(2x)}{\tan(3x)}$ is what you've got then yes?
ann.in.a.teacup
yes!!
ok do you have any progress on this so far?
i did earlier but its somewhere in my notebook of attempted calc problem scribbles lol
i thought i had an idea but can u walk me through it?
ok, let's hear your idea then
do you know derivatives?
try using sinx/x=1 and tgx/x=1 as x->0
@glacial garden Has your question been resolved?
By using [lim x->0 (sinx÷x) =1] then [lim x->0(sin2x÷x=2) ]
And: [lim x->0 (tanx÷x) =1]
then [lim x->0 (tan3x÷x) =3]
Lim x->0 [(x+sin2x÷x)/(tan3x÷x)]= [(1+2)/3]=1
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1.11b?
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need help finding second derivative of y'=(2x-y^2)/(y^3+2xy)
this is what I got it to using the quotient rule however the book says y'' is (2-y'(3y^2y'+2xy'+4y)/(y^3+2xy)
Second derivative wrt what
Trying to figure out how the book got the 2nd derivative compared to using the quotient rule on y'
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I'm getting the hang of completing the square, but this problem is confusing me. How do I convert this when a and b do not have any common factors outside of 1?
did you start by dividing by 2?
I thought you start by moving the 6 to the other side, but that would also make the other side negative (which would lead to an imaginary number).
If we divide by 2, does that turn it into 2(x^2+3.5x+3)?
what?
usually we have the coefficient of a expressed in vertex form but apparently they don’t want that, also i see no reason why you should move the constant term to the other side
it’s useless
this is how you should do it
first they divide by 2 to get
x^2 + 7/2 x + 3 = 0
then we observe that (x + 7/4)^2 contains the first two terms x^2 + 7/2 x but the constant term is different
(x + 7/4)^2 = x^2 + 7/2 x + 49/16
but we have a + 3
not a 49/16
notice that 49/16 = 48/16 + 1/16
which is 3 + 1/16
hence (x + 7/4)^2 = x^2 + 7/2 x + 3 + 1/16
and look
we have exactly what we had in our original expression but there’s the 1/16 on that side
so just subtract it from both sides
and we get
x^2 + 7/2 x + 3 = (x + 7/4)^2 - 1/16
@gritty hollow do you understand
I'm trying to absorb all of this.
i can give another example if you’d like
Can we go step by step?
sure
I get the first part where you divide by 2 on both sides.
mhm
would you like another example first?
maybe the fractions make it more confusing
I understand how to complete the square normally. Just not when a does not equal 1.
I think an easier example where a does not equal one would be good.
ok
i think it would be good if you learned how to rewrite an expression instead of it being an equation where we can just ignore the coefficient of a by dividing by it
so
$2x^2 + 10x + 25$
knief
btw, have you seen vertex form? namely
a(x - h)^2 + k
I've seen that before.
So here, we can see that the 2 and the 10 are divisible by 2.
And that the square root of 25 is 10/2.
well
the first step is to always factor out the a term
so let me walk you through this one
,,\begin{align*}
2x^2 + 10x + 25 &= 2\left(x^2 + 5x + \frac{25}{2}\right)\
&= 2\left(x^2 + 5x + \frac{25}{4} - \frac{25}{4} + \frac{25}{2}\right)\
&= 2\left(x + \frac{5}{2}\right)^2 - 2\left(\frac{25}{4} - \frac{25}{2}\right)\
&= 2\left(x + \frac{5}{2}\right)^2 - \frac{25}{2} + 25\
&= 2\left(x + \frac{5}{2}\right)^2 + \frac{25}{2}
\end{align*}
knief
if you have a question about any of the steps just ask
I can kind of see it? Can you explain the 25/4-25/4+25/2 stuff? The x^2+5 stuff seems relatively straightforward.
so i did that because i wanted to have a + 25/4
because (x + 5/2)^2 = x^2 + 5x + 25/4
so to "complete the square" i rewrote my expression to contain a + 25/4
so i could rewrite it as a perfect square
I think I get it now. So it's like a puzzle, in a way.
All you're doing is making it so that we can factor it neatly.
yes exactly
so let’s try to do the same thing in your example
2x^2 + 7x + 6
let’s forget about the zero for now
it’s good practice to be able to keep the factor of 2
like i did here
Okay, so we factor out the 2 and then focus on the parenthesis.
So we get 2(x^2+3.5x+3)
Now we have to get b/2.
$2\left(x^2 + \frac{7}{2}x + 3\right)$
knief
mhm
Which b/2 would be 7/4, which is where that comes from.
yes
Now we have to make c = 7/4^2.
mhm
yep
or you could add zero
- 49/16 - 49/16
then just do -49/16 + 3
i did it that way because i just saw i could break up 3 like that
but that really amounted to subtracting 49/16 from 3
This means that the other side is -49/16?
$2\left(x^2 + \frac{7}{2}x + \frac{49}{16} - \frac{49}{16} + 3\right)$
knief
don’t fall into the habit of moving things over to the other side just yet
only do that if they force you to
this way captures the essence of what you’re really doing
I also have to go soon, but I understand this better now.
Thank you for all of this.
you’re welcome
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Hi
do you mean the second line?
Yeah
they multiplied the numerator and denominator both by (h+7)
Oh wait I'm dumb
oop
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does anyone know how to get g(z)? i dont really understand how to get it
For a fixed z (imagine a plane parallel to the xy plane at that height), what is the area of the square cross-section of the pyramid?
Well if you fix z=0 then the area of the cross section on the pyramid is 16, yes
But in general, think of a fixed z like that plane I drew. You can think of your integral as "scanning" from the base to the tip of the pyramid, adding up the area of tiny slices of it.
g(z) should be the area of those slices
oh i see
In reality, you only need to know x in order to find the area, since the cross-sections are squares centered at the origin
So if for a fixed z you can find the corresponding x value, that should give you insight as to what the area of the cross-section is
oh i see what you mean thank you
but im still just not sure how to actually get g(z). given z = h(x-2)^2/4
Let's say z = 1.
From the equation you're given, can you find the x-value for the location of the cross section?
yeah
To do that you solved for x in the equation 1 = h(x-2)^2/4
Once you have that value, double it and you should get the side length of the square yes?
Now, if z isn't given, what if you try to solve for x in terms of z?
wait sorry how does doubling it give you the side length?
The squares are centered about the z axis.
If you find the value of x for a fixed z, that's really just where the red line touches the square cross section.
oh i think i see i
it
but then i would have to square the whole thing after too right?
Yeah
(2(-sqrt(4z/h)+2))^2
I just dont get why we need the square and - now
apparently thats the answer
From the equation you have, you get
$$(x-2)^2 = \frac{4z}{h}.$$
Technically, this yields $$x-2 = \pm \sqrt{\frac{4z}{h}}$$
Now, since $x \le 2$, we must have $x-2 \le 0$, so you need to just keep the negative root.
This gives you $x = -\sqrt{\frac{4z}{h}} + 2$
Then you double that to get the side length of the cross section, and square it to get the area of the cross section.
Azyrashacorki
oh i see now but im little confused why x must be less than or equal to 2
is it cuz im not seeing where the axis are rn
im kinda confused where they are located rn
oh nvm i think i got it
thank you
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Good morning all, how do I solve 9(3x+4)-2x=11+5(4x-1)
27x + 4 - 2x = 11 + 20x -1
9(3x+4) is not equal to 27x+4
you need to distribute properly
and likewise for the other bracket, where you made the exact same mistake a second time
ok
can you tell me what 9(3x+4) properly expands to?
also btw you have the "ask pronouns" role -- what are your pronouns?
My answer is -6
27x + 36
correct
can you show all your work leading up to the answer?
then you divide both sides by 5
no no the letter x not multiplication
Oh yes minus
it escaped me
i actually used a minus in my book
so instead 27x -20x - 2x = 11-5-36
.
right
that wasn't me reminding you to put a period
that was me conveying a bit of shock at the word "service"
do not be shocked
@sullen remnant Has your question been resolved?
Yes, it was.
@sullen remnant Has your question been resolved?
Yes
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can anyone help me explain what this is
some kind of strange little graph
it's from a set of numbers
thats all well and good but you have not given us any context
and expect us to somehow intuit something from this graph alone with zero context
the numbers arent actually from a math problem, i was actually trying to categorize genes based on if it had the phenotype, genotype or none. 7 different types of genes all combinations. i decided to add colors to make it easier and so that the colors would make sence i gave each color a number. these numbers seemed to have a weird type of pattern to it so i plotted them in python and got this
do you want me to send the full dataset?
i got your context right here
i need help finding a formula or a program that can put out the same numbers
i made something in python but it's limited to the first 3^8 numbers
if i want anything higher i would have to add another 2 lines
i'm curious if anyone here could help me find a better way of prediciting the numbers
and what these numbers are
Perhaps use a for loop and use index as an exponent? I have never used pylab before
well you seem to understand this way better than me 😅
do you maybe know what this numberset is?
Thank you
Hmm no, but I can try plot it when I have time
thank you, i've also noticed the numberset seems to be increasing at a certain amount but i don't know yet if this is a set contant value or a exponent or idk
it seems to be repeating
it seems to be divided in thirds
i have a theory this is some result of base 3 or something
What do you mean by "predicting"?
Don't you alreay have a code that generates the number you want?
you want to calculate it without using loops&ifs?
Sorry I missed a point
A smart person will always be the first to admit a mistake
but yeah the problem is that im basically brute forcing it
i have to add more lines to generate higher numbers
If you only have problems with not want to add more lines
while i<=b:
x1.append(i)
y1.append(y)
for j in range(math.ceil(math.log(i,3)),-1,-1):
if (i+1)%(3**j)==0:
y += 1-2*j
break
i +=1
what do i define math as?
oh add import math on top of the code
or below from pylab import * it doesn't really matter where the line is
as long as it is on before the while loop
you get error?
from pylab import *
import math
a = 0
b =100000
x1 = []
y1 = []
y=0
i=0
while i<=b:
x1.append(i)
y1.append(y)
for j in range(math.ceil(math.log(i+1,3)),-1,-1):
if (i+1)%(3**j)==0:
y += 1-2*j
break
i +=1
like this
oh my god calm the b down you're gonna kill my pc 😅
And by the way sorry for my mistake again, there's some error to be fixed. Please change for loop as
for j in range(math.ceil(math.log(i+1,3)),-1,-1):
I forgot adding 1 to i
I keep forget log is not defined on 0
what should i define it as??
you can just replace the for loop in the code I suggested to this one. It should solve the error
So overall code woulde be like
from pylab import *
import math
a = 0
b =100000
x1 = []
y1 = []
y=0
i=0
while i<=b:
x1.append(i)
y1.append(y)
for j in range(math.ceil(math.log(i+1,3)),-1,-1):
if (i+1)%(3**j)==0:
y += 1-2*j
break
i +=1
plot(x1, y1,'-')
show()
oh my god thank you
do you maybe know anything of this pattern?
I'm trying to analyze the data, but nothing remarkable yet found for me
it's a repeating pattern the same "staircase" appears
I don't know if this would mean anything important, But they seems to be bounded between $log_{\sqrt{3}}(x)$ and 1
Dri111
woah
hold on let me send you the original chart of numbers, i think it has something to do with base 3
oke
ooh, I think you're correct on this
the sum of the digits of n in base 3 looks similar
i didn't really know it was base 3 before i looked twice, it was originally meant as a system for deciding the color of squares 
is the number generated with computer? or is this some kinds of experiment result?
let me explain it's a little complex but you will understand it
it's a thought experiment you need a pc for
you have 7 pairs of chromosomes, aa bb cc dd ee ff and gg.
but it can also be aA bB cC dD eE fF and gG
and aa bb cc DD ee ff gG
and all the other thousands of combinations
if it has no large letters trait is non existent and it's a 0
if a pair has 1 large letter its a genotype and given a 1
and if a pair has both it's a phenotype and get's 2
so base 3
so each digit is each pair of chromosome?
yes
then why are there 8 digit?
0 is small letter small letter
oh i chose 8 for simplicity
it was meant as a little biology presentation on how traits can reapear
and what about 6, 8 and those that are not available in base-3?
no it's 8 types of chromosomes
aa is 0 aA is 1 and AA is 2
8 pairs
there are 3 variants of each pair
8 pairs
you get base 3
so for example 7 means there are total 7 large chromosome in 7 chromosome pair?
no the summing of them was just a way to find a color to them
it wasn't meant to predict anything
i asigned a color to make the chart more organized
let me just send the entire thing to you
no no it was just lack of background for me
Oh ok 😅
I can't find any specific more works, this is my best
this is cumulative form of the data you have
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Can someone look at my proof?
@half marsh Has your question been resolved?
@half marsh Has your question been resolved?
<@&286206848099549185>
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Hello I have a clash of clans question
Please don't occupy multiple help channels.
Basically: I have 5 builders that do upgrades on structures.
The question is to figure out whether the Book of Spells or the Book of Building saves a greater total amount of days when you use it.
This channel is for math bro
Yea it’s a math question
You opened two channels
Ohh sorry
Also it depends what you are trying to upgrade.
So: If we have 5 builders, each of which need to complete five upgrades that are each X days long, and we use a Book of Building to instantly complete one of those upgrades.
Because the book of spells upgrades spells when you are upgrading them and the book of building is better for building
Correct
Which leaves you 1 builder to get it to do something else
All in all usually what is the most time efficient is to have all your builders busy at all times
Basically my question is, if you have 5 builders and use a book of building on a 10-day upgrade: does it save in total 10/5 =2 days?
Compared to the Book of Spells: since in the laboratory you can only do 1 upgrade at a time (as opposed to 5 upgrades simultaneously on buildings using the 5 builders), then the Book of Spells saves exactly the amount of days that is equal to how long the upgrade is
Yesss this
But I feel like I am missing smth
Builders are not used in spell upgrades
so you can actually do both
Like, if you use a Book on a 14-day long upgrade, then you literally do not have to spend 14 days doing it
So how is it 14/5
What town hall are you
13
I am purely interested in the math of this
I don’t rly have any books rn
I have been debating which book is better
I'd say building
I give this math but feel like I am missing smth
Yes but I say spells
Cause spells saves 14 days if the upgrade is 14 days
But Book of Building saves 14/5 why is it so
Well you can only use 1 book
Haha I mean you can use any amount of books
I’m rly curious if someone can tell me what I’m missing haha
Bro clash of clans is not that serious 🙏 💔
Elixer/Gold
I rly rly want to understand which book is better
Sry gng idk that much ABT coc
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help in integrating 1/r^2 dr
1/r^2 can be written a r^-2
Power rule
(r^-2+1 /-2 +1) + C
r^-1 /-1
my problems is
r^-1 / -1 = 1/r^-1
How did we get rid of the sign -
this is not correct
that the problem im facing
$\frac{r^{-1}}{-1} = -r^{-1} = -\frac{1}{r}$
Ari
that my final answer
but im confused is there a property that states
-1 = 1/1?
?
no -1 is not 1/1 lol
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my teacher said if i cant get this right i fail
Please help
Sounds cruel
a bit harsh lowkey😂
11?!?
yes you need to focus
uhh gimmie a second
but in the mean while
<@&286206848099549185>
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a basis for {0} is not {0} because it is not linearly independent
and basis for Range(L) as {(1,1,0),(-1,2,0),(0,0,1)}
oh
so i need 3 vectors
by convention a basis for the vector space {0} is taken to be the empty set
okay
for part d
one min
i will send my proof
this works ?
so for L to be one to one i have to show that if T(v_1)=T(v_2) then v_1 = v_2
cloud ?
sure
and for onto
So
For onto
I have to show this equation has a unique solution for every x1,y1,z1
?
Oh wait wrong matrix
There
Is this also right?
Unique solution means det (A) should not be equal to 0
Rank (A) = Rank(Augmented matrix)
Correct ?
An onto function doesn't require a unique element in the preimage
The way that question is phrased doesn't make me think they want you to prove it rather than just give a yes or no answer with a brief justification.
Like for 1-1, you have that Ax = Ay and you've already shown that A has rank 3, so x = y without the formality.
Yeah but wanted to prove it to ,just in case they ask it that way in the exam
and if you don't have access to the existence of a matrix representation of the LT, then you shouldn't be writing that in the form of an augmented matrix
So Proving det(A) not equal to 0 would be sufficient ?
you've already shown that range(L) = R^3
I did?
I assumed that when I said you could have wrote a couple sentences to justify your answer but then you said you wanted to prove it, that this meant that you wanted to show it using the definitions of 1-1 and onto, by explicitly showing that for any y in the image there exists an x in the preimage such that L(x) = y
If I just show that those 3 vectors are independent my work is done
well you claim they are a basis
if they were not linearly independent, then your claim that they are a basis is wrong
Oh yeah lol
also for 1-1, ker(L) = {0} is all you need
which you also stated as part of your answer to b
I didn't know we have to use the definition of onto to prove part e
Inwill do it
You don't -have- to do anything, it's just not clear what you are trying to practice
I want to prove part d and e
your answers to parts b and c should instantly tell you the answers to parts d and e
:pensibthis:
what converse? this is an if and only if. you should be more attentive reading stuff
but
no that is just the backwards half of the iff
say i have the statement "A set V is considered a vector space if and only if V contains 0"
its converse would be "If V contains 0 then V is a vector space"
no
but this isnt true always right
this stmt is false anyway
but our point is a statement of the form A <=> B doesn't have a converse at all
do you understand that A <=> B is a different kind of beast than a one way implication?
A <=> B means "A implies B, and B implies A"
it is a two-way implication
do you understand this?
yes
so A => B and B => A are converses of each other on their own
so "if and only if" is a two-way implication ?
okay so ker(L)={0_v} means L is one to one
and for onto
🙏
i will do it later
thanks everyone
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calculus how do i use the integral(ax+b)^n formula properly here
just the equatio nthat comes after b.
you can't because this isn't an integral of that form.
oh
is there a shortcut to this kind of question then
or do i always have to just expand it out then integrate
im just kinda lazy
gotta expand
there's not really any sense of "always"
or use hyperbolics, but i doubt that makes it much easier
but for this one yes you have to expand. it is not that bad here
it doesn't
yeah you would still have to reduce the power
Integration isn't like differentiation. There isn't a universal recipe to solve integrals. You just have to use your intuition, which comes with experience.
yes yes i see
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Prove that the vectors v₁, v₂, ..., vₖ are linearly dependant if and only if there exists real numbers λ₁, λ₂, ..., λₖ that arent all zero such that
v₁λ₁ + v₂λ₂ + ... + vₖλₖ = 0.
Are all nonzero?

1 sec
Did you mean arent all zero
also what's your definition of linear independence
bear with me guys im tryna translate the textbook from swedish to english, my bad 😭
I suppose that this would be that one of the vectors can be expressed as a linear combination of the other
yes this is derived from that:)
Yes
Sorry for the confusion, thats right
This probably isnt very difficult I'm just struggling with drawing conclusions from the proof that's in my textbook (and wikipedia, ill attach it) so that I can actually somewhat understand it
So they assumed that a1v1 + a2v2 + ... akvk = 0
And used that to express one of the vs as linear combination of the others
Thus showing its linearly dependent
E.g. 2 * [1, 2] + (-1) * [2, 4] = 0
And we can rearrange this to get
[1, 2] = 1/2 [2, 4]
And this shows that its linearly dependent
And we can do the opposite similarly
extending off of that, could you interpret all lambda = 0 as a non-real combination of vectors, proving that it is infact linearly independant?
i.e. given a sequence of vectors that are linearly independant, the only way to create a combination is to divide by zero which is undefined
Thats not a good argument honestly
If the only solution is the one where all lambdas are 0 then its linearly independent
Its linearly independent because if it was linearly dependent, then we would have v1 = some linear combination of other vs and we could rearrange that to get a non-zero solution for the equation we started with
I understand
This really was not that complicated after all, think i just needed a human to talk to about it
Thank you a lot for the help 🙏
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Hi, I got stuck when trying to check if my Method of Moments Estimator is unbiased. So I have done the following. \
\
Gamma Distribution is defined as
\begin{align}
f(x) = \frac{x^{\alpha - 1} e^{-x/\beta}}{\beta^\alpha \Gamma(\alpha)} \quad \text{for } x > 0
\end{align}
\
Let $x_1, \ldots, x_n$ be an i.i.d sample with $\gamma(\alpha, \beta)$ distribution. \
\
The gamma's moment-generating function is
\begin{align}
M(t) = E[e^{Xt}] &= \int_{0}^{\infty} e^{xt} \frac{x^{\alpha - 1} \exp\left( -\frac{x}{\beta} \right)}{\beta^\alpha \Gamma(\alpha)} \dd{x} = \frac{1}{(1 - t\beta)^{\alpha}}
\end{align}
\
In such way, the first moment and second moment is
\begin{align}
{\dv{M}{t}}(0) &= \frac{\alpha\beta}{(1 - t\beta)^{\alpha + 1}} \Bigg|{t = 0} = \alpha\beta \
{\dv[2]{M}{t}}(0) &= \frac{(\alpha^2 + \alpha)\beta^2}{(1 - t\beta)^{\alpha + 2}} \Bigg|{t = 0} = (\alpha^2 + \alpha)\beta^2
\end{align}
\
So, the expectation and variance of gamma is
\begin{align}
E[\gamma(\alpha, \beta)] &= \alpha\beta \
V[\gamma(\alpha, \beta)] &= (\alpha^2 + \alpha)\beta^2 - (\alpha\beta)^2 = \alpha\beta^2
\end{align}
\
We got the following system
\begin{align}
E[\gamma(\alpha, \beta)] = \sum_{i = 1}^n \frac{x_i}{n} &\iff \alpha\beta = \sum_{i = 1}^n \frac{x_i}{n} \
E[(\gamma(\alpha, \beta))^2] = \sum_{i = 1}^n \frac{x_i^2}{n} &\iff(\alpha^2 + \alpha) \beta^2 = \sum_{i = 1}^n \frac{x_i^2}{n}
\end{align}
\
Now.. solving the following system for $\alpha$ and $\beta$
\begin{align}
\hat{\alpha} &= \frac{\overline{X}^2}{V^2} \quad \text{Note that } \overline{X} = \sum_{i = 1}^n \frac{x_i}{n} \
\hat{\beta} &= \frac{V^2}{\overline{X}} \quad \text{and also } V^2 = \sum_{i = 1}^n \frac{x_i^2}{n} - \left( \sum_{i = 1}^n \frac{x_i}{n} \right)^2
\end{align}
\
Once done all of that, I should show if $E[\hat{\alpha}] = \alpha$ but not sure how to process with $E\left[ \overline{X}^2 / V^2\right]$
A.L.I.C.E
@wind venture Has your question been resolved?
@wind venture Has your question been resolved?

Wait, give me a second to brush up my MoM theory
Yaaaay 
Aaah it is just your last step I think? So you want to show now $E[\alpha] = E[\frac{X^2}{V^2}] = \alpha$, is that correct?
Mathemagician
Yes I got stuck because of that /V^2
just use the proporty of Expectations that says: $E[X/Y] = E[X]/E[Y]$
Mathemagician
: O
Lemme check
Btw, $E[\overline{X}^2] = E[\overline{X}]^2$, that is true, right?
A.L.I.C.E
Yes, since $\bar{X}$ is just a constant, it is correct (but this is not in general true)
Mathemagician
Can it be that your Variance should be $V^2 = \alpha \cdot \beta^2$ instead of just $V$? Otherwise, it will not work, I think the notation should be $V^2$, no?
Mathemagician
Hmm, how so by instead of just V? I've written it as V^2, right?
Yes but you say in equation 6: $V = \alpha \cdot \beta^2$, but later in equations 9 and 10, you use $V^2$ instead of $V$, right? That is what might give problems in the calculation
Mathemagician
Ahhh sorry, I meant like V[X] of gamma instead of V^2 of the sample
No probs 🙂 But then the problem is solved and you can show the unbiasedness right? Or are you still stuck?
I'm trying to compute E[V^2], I used to do it turning it into chi-squared
That usually works with normal distributions XD
but why do you need E[V^2]? I think it should be E[V], no?
Hmm, you mean like $E[\overline{X}^2 / V^2] = E[\overline{X}^2]/E[V^2] = E[\overline{X}]^2 / E[V]^2$
A.L.I.C.E
noo, this:
I think there shouldn't be a V^2 in the first expectation in the first place
I got lost 
I computed sigma^2 in there
Hmm, it should not be V^2 = sigma^2, should it?
no exactly!
It should just be V
and therefore, it should also just be $E[X^2/V]$ instead of $E[X^2/V^2]$
Mathemagician
Hmmmmmmmmm I see, so technically I can do like this $E[\overline{X}^2/V] = E[\overline{X}]^2 / E[V] = (\alpha\beta)^2 / (\alpha\beta^2) = \alpha$
A.L.I.C.E
yess! Indeed! thats the way to go girl

I thought that I was not allowed to change it like that
I mean, it feels like cheating XD
but you don't change anything, you started with V and you finish with V, you never introduced V^2, so you should not use V^2 :))
Yeah, thanks for the help !
No probs, good luck!!
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whats your question
ive only seen questions like this
without the other number being squared
so im kinda confused
You need to factor that?
yes
okay
Write $-17xy = a + b$ such that $ab = (3x^2)\cdot (20y^2)$
casework
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This is the answer for exercise 3 I just need someone to explain polar coordinates and what exactly happened in the second diagram, it looks like the velocoty is dicided into perpendicular components but why does the writer call them axes? Also toward the bottom of the page when velocity component is described is it a typo when they write r again besode r dot and theta beside theta dot(dot is the time derivative notation)
Magical Math Escape Game
Objective: Discover which magician managed to rob a bank without leaving any trace by solving math problems.
The Suspects
(x+2)(x+4)
(x-2)(x+4)
(2x-2)(x-4)
(5x+7)
(3x+6)(2x+4)
Names and Expressions of the Suspects:
Lionel Séchal: 6x² - 2x - 8
Agée L'Witch: 2x² + 22x + 24
Luke: 2x² + 2x - 8
Rachel Atlas: 2x² - 10x + 8
Merritt Lockline: 3x² + 18x + 24
Thaddeus Bigallet: 25x² + 70x + 49
Magic Program 1:
Choose the number (-4)
Square it
Subtract 7
Divide by 2
Add 5
Magic Program 2:
Choose the number x
Add 7
Multiply by 2
Add the initial number
Execute this Scratch program with (-3), then with the letter x:
when [green flag] clicked
ask [Choose a number] and wait
set [my variable] to [answer]
add [7] to [my variable]
set [my variable] to [my variable] * [2]
set [my variable] to [my variable] + [answer]
say [my variable] for [2] seconds
Magical Items and their Associated Numbers/Expressions:
Crystal ball: 7
Magic wand: 12
Potion: 3x + 14
Hat: 2x + 13
Magic book: 5
pls help
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@sour tulip Has your question been resolved?
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Idk howw
Ohh
The formula is just r(theta)
That’s it
U multiply your radius with your angle in radians
The angle of your arc length right
It’s 30
U convert it into radians
Then you just multiply it with your radius
r= radius (theta)= angle in radians
@tribal marten Has your question been resolved?
I still don't get itt😭😭
Can you like, Show stoppp or something
You know radians right?
Yel
Okay
Ohhhhh
Oh it’s because when you multiply 15 with 1/6
It becomes 15/6
U simplify the fraction
It becomes 5/2
Yesss👍
Yes, 15 is the radius of your circle
Yes because that’s the angle of the arc length
Can you make a problem ill try to solve real quickk
Sure
Couldn't find an attached image in the last 10 messages.
Do you know thiss?
Lemme try first
Okiee
Yes i knoww
Then?😭
But how to find value of X
Yes all together
Then what nextt
Cuz together they add up to 360
U keep all your x on the LHS
And you bring your constants on the RHS
😭😭😭
What’s up💀
Don't get it lol
🧍♂️
lol
Where did 31 and 465 came fromm
Thats the thing i need to know so that i got it
@young forge
You combined all X?
Ohhhh
Okay
I got itttt
Thank youuu sooooo muchhh
Really appreciate it:))
@young forge Thankk you bro
No problem🙏
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in slve a can't we consider domain x>or=4? just like we did in slve b?
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@turbid tiger if you have x = -5 then the expression in part a is still defined.
the reason for the restricted domain in part b is due to the sqrt, you can't take the square root of a negative number.
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help
idk how to solve this
do you use law of sines or cosines
and how do you use them do you jst plug x and y?
@proper saffron Has your question been resolved?
You dont need sine rule or anything here. A simple angle chase would get you the answer
Assume one of the angles, say A, to be some value.
Then you can work from that and find the angle at C in terms of the angle at A
how do we know thats y
$$|AC| = |BC|$$
casework
oh so you just put a random value and then you get the correct answer?
ohh
not a randome value. Some variable like A or smthn
oh
so it would be 2a+b=180?
because bottom angles are the same right?
its an icosloes
triangle
and then a+c=90
How do you get that?
oh
wait
a+c/2=90
you divide whole thing by 2
yea, but that doesnt seem to help at anything does it?
k
Hint if you want: ||calculate the angle KLB||
wait also the line in the middle doesnt do anything right?
You have like a million isosceles triangles. If you just use every single one of them. You have what you need
hold on
it is helpful

Pretty sure thats called wrong
ok then i have no clue
whyd you say the angles are equal?
Who says they are the same
it looks the same
ngl, it doesnt
ok nvm
and they do say its not to scale
oh
- It isnt even to scale
- Even if it was , looks right doesnt mean it is right
- you should never even assume the figures are correct. They are more of a visual guidelines
oh ok
idk how to continue
like no clue
Do you know exterior angles of a triangle?
i think
Like KLB is an exterior angle of the triangle CLK
And that triangle is isosceles
you can try to write the angle KLB in terms of the angle ACB
No
Bruh, you just said blc is 180 here.
exterior angle is 180- inner angle
oh
ok
i cant
i need more help
can you answer this?
can you show your work? Like show me a diagram you drew and mark the angles A and C on it
thats fine. I too do that a lot
ive just been noting down what we have been talking about
Ok, any other angle you see thats easy to mark?
to calculate?
yea.
or just mark
I meant mark in the figure in the sense that you can calculate it
KL = CL means there is one angle that is easy to mark
i think that one
near the l
OH
wait
i think i know
wait kl is the angle opposite to the one i did rn right?
and cl is the very top one?
then i think ik
oh
That means CLK is an isosceles triangle
So, with that information, what can you say about the other angles in the triangle?
ok
in clk
is also 2b+c=180
right?
Like, if you think so, you must provide a reason with each statement you make
can you name it? I dont know which angle you marked 
k
yeah idkk how to name angles
you can name angles with the three vertices. if the angle is ABC, then the angle is at the vertex B, and formed between the lines AB and BC
ohh
ok
so ABL is the angle near corner b
yes
.
yea
can you show how?
wait no scratch that
ok
y is the side
so this is also not correct
oh i used the wrong variable
can you rewrite it then? with the correct variable
2z+KCL=180
whats z? and no, i dont think thats correct
the 2 angles inside triangle KLC
coz KCL and CKL are the equal angle in this triangle
mhm
what do i do next
We are still at the same step You gotta find the exterior angle KLB
wasnt that KLC-180?
180-KLC
oh
can you give me a hint
another one
maybe i can figure it out