#help-49
1 messages · Page 54 of 1
Well its 1
yea, i intergrated already, my mistake
Right, good!
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Hi. Should i simplify it further or?
@misty marlin Has your question been resolved?
<@&286206848099549185>
yehee
I should?
this sounded like Michael Jackson in my head
.
there's a problem in soln
Mistake?
2nd last line
yes mistake
you just can't terminate numerator values when they are in addition or substraction format
I see that was dumb mistake
not a problem.... just solve that and then see...
Okay
Should i simplify it further or no
what bout cos4t
or you can try further
Simplify it further
?
Sure
The ans will come cotx
wait you taking it that way........
Ans?
You recheck your work
Cotx is ctgx right
well just write the question for me
Simplify
Yep
the trigonometric question
Wlcm ig ^^
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
Thank you. I just got the same.
Wlcm ✌️
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If the formula in the graph of the first picture (PMF) represents the probability of getting EXACTLY k successes after n trials (with a fixed success rate = p) and the one in the second pic represents the probability to get AT LEAST k success (CDF), what is the formula to determine the probability of getting AT MOST k successes after n trials? Is it just 1-CDF?
I'm confused because the respective functions on python look like this, instead of the other way around:
def calculate_probability_at_least_k(k, n, p):
probability = 1 - binom.cdf(k - 1, n, p)
return probability
def calculate_probability_at_most_k(k, n, p):
probability = binom.cdf(k, n, p)
return probability
@grizzled torrent Has your question been resolved?
@grizzled torrent Has your question been resolved?
@grizzled torrent Has your question been resolved?
@grizzled torrent Has your question been resolved?
Yeah usually the CDF is a monotonically increasing function and displays the probability for k or less than k successes
That's why it's cumulative, b/c if you go from left to right (i.e. from k= -infty to k= +infty) you add up all the previous values of the PDF essentially
So I'd say the screenshot has the wrong idea when it just writes "CDF" for this situation
What the screenshot display is, to me, the function 1 - CDF where CDF is the cumulative distribution function associated to the PDF from the lower graph in the first picture
okay, but are they both (at least, at most) CDFs? btw, During this time I realized that the function I was looking for is not in fact 1 - CDF
can you confirm for me that these are the right functions and the graphs look alright?
at least k:
at most k:
By definition a CDF associated to a probability distribution is the function that associates a number k with the probabilty of getting an outcome smaller or equal to that number
ah okay, so the upper ones aren't CDF
Yea I wouldn't say so
would they have a name?
I mean the first screenshot is also something cumulative, but it doesn't come from a probability distribution in the same way
It's just 1 - CDF, I don#t think that has a name
The screenshots look alright
I don't think it is 1-CDF
for example, let me think
n=4, k=4, p=1/2
P(X ≥ k) = 1/2⁴
P(X ≤ k) = 1
no wait that's not the point
I think you're right then
so, in this case, if the bottom graph is the CDF(k;n,p), the top one is some f(n;k,p) equal to 1-CDF(k;n,p)?
yeah sounds alright
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can you find the formula for the nth term of the series?
Yes
if you're trying to be cheeky and use the answer choices, there are two of these that are already way too small to be the right answer
Multiplication (1 to n) (2n-1)/4^n
You meant by adding first few terms
@wary thorn
in fact, the first term is enough to make you eliminate one of them
I've sent you it already
Yes
B and d
Multiplcation of 4
Any multiplication sinx/x formula?
@bleak pier Has your question been resolved?
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I need to find the inverse of the function f(x) = x^2 + 10x + 28. This is what I've got so far, but I am confused as to how I would continue:
y = x^2 + 10x + 28
x = y^2 + 10y + 28
x - 28 = y^10 + 10y
I would factor out the y, but I don't want to define f(x) in terms of y.
The first equation is sufficient, you need to solve in terms of x
I don't get what you mean by that. What's the 'first equation' you're referring to?
The first equation of the list
y = x^2 + 10x + 28
This becomes x^2 + 10x + 28-y = 0
If you consider y fixed it becomes a polynomial equation you can solve in terms of x
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Let k be the circle described around the triangle ABC. If P and Q are the points where the bisector BC intersects the lines AB and AC, prove that Q is the inversion of P. My friend who is grounded needs help and he cannot use discord.
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is my mistake the fact that i turned the hyperbolic trig functions into their complex forms?
hi
my issue is when i get to another part of the question where i'm supposed to find max curvature, there isn't a t i can work with
<@&286206848099549185>
nevermind i got it
.close
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can someone explain? is this some log property?
What is the question
🫎 Chmoosey 🫎
Lhopital
x instead of n i think but yeah
they appear to be multiplying numerator and denominator by x?
yes limit approaches 0
is this your work?
are you just confused on how to do it?
my internet.....
somehow it says
25^x - 1 / 16^x - 1 = (25^x - 1 / x * x/16^x-1)
my friend's trying to practice for exam on webnesday
iam confused how it equals that
they just appear to be multiplying numerator and denominator by x, they are multiplying by 1 essentially
The 2 xs cancel each other out
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A bit stick in terms of how to create an equation for this
I thought abt creating an equation in terms of the difference (the difference differs each by 1)
so 2(n-1)1 but idk
hm?
Do you know the formula for the sum of
1 + 2 + 3 + ... + n
Yup
What is it
n/2(a+l) l = last value that is if you have the last value if not then the second equation is
n/2 ((2a+(n-1)d)
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ax+by=10
2x-ay=0
solve the pair of simultaneous equations for x and y, expressing your answer in terms of a and b
i keep on getting 0 = 0 somehow
what did you try?
yeah if 2x - ay = 0 then x = ay/2, then you substituted that into the first equation?
ye
what did you get when substituting
((a^2*y)/2)+by=10 ?
yeah
A brief description and guide on how to use me was sent to your DMs!
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no when you solved this equation
the whole point of the substitution was that you turned an equation that had both x and y into an equation that just has y
then you solve for y
and then lastly you plug that back into your substitution to solve for x
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i want the determinant of those questions and whatever they say too
what
for the first one, did you compute AB?
what do you get
a matrix
i dont hace a phone to send the pic rn:((
can you type it
i just wanna know what to do w the equations
what you get if you compute AB is probably important to find that
i was thinking that if it was the identity times a constant, then you would have found the inverse up to a multiplying constant
i think
the matrix i got
i have to multiply it w x y z
and keep it equal to 10 8 and 7
yes i got it lmao
this is what i was saying earlier, you find the inverse, and multiply on both sides to solve the equation
,, Ax = b, x=A^{-1}b
okay nvm i didnt get it
Bair
can u maybe type it or write it:((?
write what
like how to do the second one
i didnt get it
i understand the formula idk how to apply it
you are given A and b, and are asked to solve for x
you are given that
$$\begin{bmatrix} 1 & 2 & -3 \ 2 & 0 & -3 \ 1 & 2 & 0 \ \end{bmatrix} \begin{pmatrix} x \ y \ z\end{pmatrix} =\begin{pmatrix}1 \ 2 \ 3\end{pmatrix}$$
Bair
left hand multiply both sides by the inverse of the coefficent matrix
yeah thanks bro
$$ Ax = b, x=A^{-1}b
A^-1 A x = A^-1 b
I x = A^-1 b
x = A^-1 b $$
kr
i already wrote it
oh
this person is confused about something else
did what
findinf A^-1
mein bhi indian hu bhai
12th mein hee hu bc rona ara hai
ok do you still need help with something?
yeah they can't find the inverse of a 3x3
bhai tu mereko paper pe solve krke dede
usse phele vala mera sahi aa gya😭😭
i dont think bro is indian
😭😭 can u solve thr whole q and send it cuz im legit half step away from crying
no, that's a skill issue, just do it carefully
hahahahhah
bhai sun ek kaam kar yeh sab bakchodi chod
google pe na hai bhai
sab karne ke bad hee yaha ayi hu lmao
im weak as shit
kya baat kr rhe ho
math mein
disrespectfully baat kr liya meine 😭
jaldi realise ho gya
sun
😭 lmfao
kya nhi samaj mein aa rha hai
uk
who tf made this shit
imperial
college
uk
agar se abhi bhi nahi samaj mein aa rha hai toh i can explain on vc or something
okie
@vague burrow Has your question been resolved?
@vague burrow Has your question been resolved?
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what in the world is the part I highlighted in red? Is it asking for the 2nd derivative or 3rd
It’s asking for the first derivative wrt x and the second derivative wrt y
The order in which you do the three derivatives doesn’t matter
so I derive them seperately and combine them together?
You differentiate it once wrt x
And then you differentiate the result twice wrt y
oh i see
let me try and lets see what happens
ah got it
thanks kheerii C:
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Hi, i just need to be checked. Is this correct? Thank you for giving me your time ❤️
the text in book is find sin x/2, cos x/2, tg x/2, ctg x/2
I can't read anything here
@misty marlin Has your question been resolved?
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I have to find a polynomial of degree 4 with F(x, y) = 0 and x = r cos(φ) and y = r sin(φ)
does this work?
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so $1<x_1,x_2....x_n>$
ƒ(Why am. I here)=I don't Know
ƒ(Why am. I here)=I don't Know
is that it?
It might be a different thing
Sometimes it denotes the identity linear mapping, for example
If 1 is the unit of F, then 1(x_1,...,x_n) = (1x_1,...,1x_n) = (x_1,...,x_n)
I think it's not
You should use the definition of $\lambda x$ when $\lambda\in F$ and $x\in F^n$
d
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can someone sanity-check my calculation here? I'm not too sure I did this right (matrix multiplication)
It's good
.close
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$a \in \mathbb{R}\
a^2 = a + 1\
log_a(2a + 1) = ?$
Oğuzhan
Can't use calculators
This is a question from Turkish University Entrance Exam which I've entered today
And this was the only question I couldn't answer
(This is a simplified version of the question, if requested I could send the whole question, but it's most likely not necessary)
Are you supposed to simplify this
In terms of log_a
It needs the answer
Also a > 0
Let me type out the entire question with the options
2a + 1 = 2a^2 - 1 = (sqrt2 a - 1)(sqrt2 a + 1) is all i'm seeing
you could split that product up with log properties but i don't see any nice simplification
i mean if they just want the answer, why not just solve the quadratic for the positive root and substitute for a
$a,x,y \in \mathbb{R^+}\
\
log_a(x),\text{ }log_a(y),\text{ }log_a(x + y)\
$is a series of numbers sorted from smallest to largest and all of its elements are consecutive integers.\
What is the value of $log_a(2a+1)?$\
A) -2\
B) -1\
C) 2\
D) 3\
E) 4
Oğuzhan
so where did the a^2 = a + 1 come from in the question?
ax = y
ay = x + y
=> ay = y/a + y
=> a = 1/a + 1
=> a^2 = a + 1
ax comes from log_a(x) + 1 = log_a(ax)
Similar for ay
how do you know ax=y???
yeah i'm confused now
Because they are consecutive
log_a(x) + 1 = log_a(y)
Therefore this
But how do you proceed from here
have you tried just solving the quadratic?
Maybe we have to use the fact that the log_a(x) is an integer but I don't see how
It gives a = (1+sqrt(5))/2
I even approximated the value of a in the exam
But it leads to nowhere
so then 2a + 1 = 2 + sqrt5
oh
Yes
and it's a matter of checking which of those powers you have to raise (1 + sqrt5)/2 to to get 2 + sqrt5
why not just check the 5 options?
y/x = (x+y)/y
$\log_{a}(2a+1)=\log_{a}((a+1)^{2}-a^2)$
2a+1 = a²+a
log_a(a²+a)
= 1 + log_a(a+1)
= 3
🫎 Chmoosey 🫎
There are 40 questions and none of them should require you to check the options
I think this is the solution wait
Where did the first come from
add a
ye
a^2 = a + 1
Where did value ofv2a+1 come from
yeah that's clever
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I try to understand Universal Approximation Theorem but before understanding the formal proof, I would to understand this:
https://www.desmos.com/calculator/cfvtjusqmq?lang=de
how can it be that adding n_i together approximate the function f ?
Is there a geometrical interpretation or a better intuition?
Please open your own help channel
Since ABE and ACD are similar and CD corresponds to BE, what can we say about p
thats its 4..?
Similar, not congruent
oh
In similar triangles, the ratios of corresponding side lengths are the same
In this case, AB corresponds to AC and BE corresponds to CD
yeah
So what can we say about p in terms of the lengths of those other line segments
how?
We know the values of each of these, so what equation do we get if we substitute those in
It does say
p is a number, we just don't know what it is yet
So CD is p
So if we put all of our values into this equation, what do we get
Right
yeah
Last time we set up this equation #help-49 message, what will we use this time
Well, q is part of AD
So we want to use the side corresponding to AD
The corresponding side to AD is a side of ABE
We want to find the length of AD, remember?
And the side corresponding to AD is AE
And we're going to use this fact #help-49 message
Right, but what can we set equal to this
cd/be=ac/ad..
The value of AD is AE+ED
so 8q
No, 8+q
if we add tho ts 8q tho, no?
No, 8q means 8 times q
oh yeah
So now, what are the values of each of these
What do we get?
And then?
4 multiply 8+q
Right
i got 32q.
so 32+q.
Not quite
or 32+4q
a(b+c)=ab+ac
divide
ohh
i see what u mean
so it wouldbe
57.6=32+4q
we move 32 to the other side
57.6-32
which is 25.6
so 25.6=4q
25.6/4
Right, which is?
If we scale one side of a cube by 3, how much do we scale the whole cube by
If I have a cube that's 1x1x1 and another cube that's 3x3x3, how many times large is the bigger cube
6x6x6
pardon
😭
no I mean how many times large is the volume of a cube of side length 3 than a cube of side length 1
how do you get 12
6x2
why 6x2
what is the volume of a cube
right so what is the volume of a cube of side length 2, and what is the volume of a cube of side length 6, for example
Cool what's 216/8
Yes
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can someone just explain to me how to differntiate cosec cubed
write cosec as sin^-1 and see if that helps
Chain rule-
power chain
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did i find the derivative of this function correctly?
,rotate
Looks correct
thank you
Wait one small mistake the end
no
(x-3) - 2x = -x - 3
you messed up in the last step
Btw, you can always check your derivatives from:
https://www.derivative-calculator.net/
I used to do it when I was learning derivatives. It also shows you steps so you can see where you messed up
Solve derivatives using this free online calculator. Step-by-step solution and graphs included!
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here is my work
i am going to ask this question in the good topics
.close
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hey how do I solve this
draw a right triangle with that angle
how should you label the edges such that cot of that angle is 9/5?
$\cos{x} = \frac{9}{\sqrt{106}}$
rynite
no thanks 👍 , seems like I haven't read the question correctly from the beginning.
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They just decree it to be so
no
Why do you add vectors entrywise normally?
oh right
You just decree that’s how addition is done
I know, but using the definition of multiplication for complex number, there's a + , right?
We don’t know what a complex number is
ah yes, that;s how I approach this

going be be hard to forget everything I know
That’s unfortunately how you gotta start

Yep, that’s the whole idea of these problems
To get you to unlearn and start from the building blocks
You get to now build all the intuition from logic
Multiplication isn't necessarily "defined" that way but rather it can have any definition that satisfies those properties
I whole heartedly think it’s better to start with some beginner proofs in group theory before doing vector spaces
Vector space axioms look confusing
Group axioms are much simplier to look at
i had no trouble with vector space axia when i was in linear
that makes sense, I never truly understood the abstract parts of linalg until after group theory
but i think i easily got the "these are the rules you can play by and no others" thing
okay, so let me start by proving the identity
it's trivial to show that $0 \in V_s$
ƒ(Why am. I here)=I don't Know
thats the plural?
by setting a=b=0
Have you proved the axioms from the start
they're axioms
how can I prove axioms
I mean show that the first few axioms hold
I was taught that axioms don't have proofs
For the given definition of addition and multiplication
I worded that poorly my bad
Have you shown this addition is associative
ah prove that V_C satisfied the axioms I see
To prove that something is a vector space you prove that it satisfies the axioms
ok, so let $u=a+ib$, $v=c+di$ , $w= e+fi$
Yeah let him try it out
ƒ(Why am. I here)=I don't Know
so we have $a+ib+ (c+e)+(d+f)i$
ƒ(Why am. I here)=I don't Know
Woah you’re mixing up + signs that matter and don’t matter now
I don't follow
The + in a + ib has no meaning
why
“a + ib” is 1 symbol that represents the ordered pair (a, b) ∈ V x V
I still don't follow
You can alternatively see the definition of addition on $V_C$ as
\begin{align*} + : (V \times V) \times (V \times V) &\to V \times V\ ((a, b),(c, d)) &\mapsto (a\textcolor{red}{+}c, b\textcolor{red}{+}d)\end{align*}
Frosst
The question now is… what is this red plus?
an operator
Where does it come from
no idea
Hint: ||look at the very top of your question||
Every word is exactly written as needed in these questions
from the fact that $V$ is a real vector space?
ƒ(Why am. I here)=I don't Know
You assume no more, no less than you HAVE to
What does this mean?
going to be hard to get used to
oh
they have defined (u,v)
What’s special about V
nothing
It’s more than just a set
I'm really confused
The 3-tuple (V, +, • ) is a vector space
oh
In particular, it looks like $(V, \textcolor{red}{+}, \textcolor{red}{\cdot})$ is a vector space
Frosst
why is the + and $\cdot$ important
ƒ(Why am. I here)=I don't Know
It’s the operations
If you don’t tell me how to add and scalar multiply on my set V, I don’t have a vector space structure
I see
so each set can have different deffinitions opf addition
Of course
so v+u could be defined to always be 1?
Absolutely
okay
But then perhaps you may not have a vector space…
sorry for teh stupid questions
These are not stupid questions at all
{0,1} is a vector space, no?
No that’s a set
You need to tell me how to add and where I can find scalars and how I can multiply them as well
I see
ƒ(Why am. I here)=I don't Know
No can do
not sure
You’re still mixing up the fake + with the real +
Maybe it’s a bit hard to think about it so I’ll say it
The red plus is inherited from the vector space structure of V
By construction now, the new + on V_C inherits all the properties of the red +
hmm, okay
It happens because you’ve defined the + on V_C by the red + on V
And we know the red + is associative and commutative
hmm,okay
Why do we know this?
from teh axioms of vector spaces
so this give me $(a+c+e)+i(b+d+f)$
ƒ(Why am. I here)=I don't Know
Let $(V, \textcolor{red}{+}, \textcolor{red}{\cdot})$ be a real vector space
Frosst
Yes
and this proves associativity, right?
I think you should work with ordered pairs
Rather than the a + ib form
Because the + in a + ib is fake
You may get confused which is which
you need my \red \yellow \purple \green \blue macros
Tbh you didn’t really do associativity
Probably do 😭
oh right
$(a+bi+c+di)+e+fi= (a+b+e)+(b+d+f)i$
ƒ(Why am. I here)=I don't Know
let $u, v, w \in V_C$, and $u = (a, b),, v = (c, d),, w = (e, f)$
Frosst
\begin{align*}u + (v + w) &= (a, b) + ((c, d) + (e, f)) \&= (a, b) + (c + e, d + f) \&= (a + (c + e), b + (e + f)) \&= \textcolor{blue}{((a + c) + e, (b + e) + f)}\&= ((a+c), (b+e)) + (c, f) \&= ((a, c) + (b, e)) + (c, f)\&= (u + v) + w\end{align*}
a proof of associativity looks like this
Frosst
hmm, I see, thanks
this is the proof written is excruciating detail
you should get used to doing them in excruciating detail at the beginning, then once you are comfortable with it, you can start ommiting things not because they aren't important, but because you will be able to do them if you wanted to
the blue line is where i used the associativity of the red plus
so a. proof of commutativity would looks something like this when written in detail ?
$v+u=(a,b)+(c,d)$
ƒ(Why am. I here)=I don't Know
$v+u=(a+c,b+d)$
ƒ(Why am. I here)=I don't Know
u+v=(c,d)+(a,b)
$u+v=(a+c,d+b)$
ƒ(Why am. I here)=I don't Know
I'm proving v+u=u+v
you dont really want to do this
you want to start with u + v
then use the definitnion of + to get to v + u
if you do it this way, this line is incorrect
it's not wrong but we dont know this equality is true
(it is in fact true but you need to prove so)
$u+v=(c+a, d+b)$
ƒ(Why am. I here)=I don't Know
that is indeed true
so now what?
Frosst
what did you want to prove
v+u=u+v
if in doubt, look at this and think to yourself how i moved from 1 line to the next
which addition, and how do you know it's commutative
$v\textcolor{blue}{+}u=(a\textcolor{red}{+}c,b\textcolor{red}{+}d)$
these are not the same + signs
Frosst
this is gonna be a very common occurence
literally every reasoning from 1 line to another will be "from definition"
because that is all we've got
going to take a while to get used to this
it will, and dont beat yourself up for it
this is like actual proper linear algebra in the abstract sense
most highschool/first years encounter this in the concrete example of R^n they dont even know there's different + signs
now to prove the identity element
sure
$a+bi+0$
ƒ(Why am. I here)=I don't Know
=$a+0+bi$
ƒ(Why am. I here)=I don't Know
which is simpley a+bi
$(a+a-a)+bi$
ƒ(Why am. I here)=I don't Know
$a+ib +(a-a)$
ƒ(Why am. I here)=I don't Know
if you want to do things to each entry you need to use the form (a, b)
this also does not parse
$a+ib \textcolor{blue}{+}(a\textcolor{red}{+}-a)$
Frosst
this is what you wrote
but
the blue + is defined between 2 elements of V_C
$a \textcolor{red}{+} - a$ is not an element of $V_C$
Frosst
is this right?
yep
show that (0, 0) behaves like the 0 vector in V_C
ie, show that it has the property you want from it
for any v in V_C, v + (0, 0) = v
show this
it does (a,b)+(0,0)=(a,b)
it;s a 0 vector
Frosst
use the definition of the blue plus here
using the defn I'm getting (a,b)
I'm not too sure tbh
yes
$(a\textcolor{red}{+}0, b\textcolor{red}{+}0)$
Frosst
this is an important step
okie
we've defined the blue plus by the red pluses
in this manner
now we say, aha, let me pick the 0 vector from V, and put them in the first and second slot of a thing in V_C
im going to temporarily name the zero vector in $V$ by $0_V$ and the zero vector in $V_C$ by $0_{V_C}$
Frosst

