#help-13
1 messages · Page 92 of 1
side is
20 / root 2
perimeter is 80 /root 2
1/root 2 = a/10
a is 10/root 2
ap is 800/2
1/2 ap is 200
which is correct
i dont know what is wrong here
im getting it right
so this formula is right?
which one then
i messed up somewhere i dont know where
oh right
maybe try to come up with one yourself
i'll do that
you can refer the above messages for the moethod
method
sorry for not being helpful
thanks for the help
yw
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Hello?
Is it a test?
No it's just a sheet my parents gave me
Because I didn't go to school this week and this is what we learned and I got no clue what any of that stuff is
what do you need help on
All of it
all?
Yea
have you tried
im not going to do a whole 30min paper for you
Fair
do what you can
and ask for what you cant do
if you dont understand the concepts i can explain them
So what is that..
$550\leq w < 800$
ColdTee
What is it?
And you have to show it on the number line
It means the value of w lies between 550 and 800
[550,800)
Closed interval 550 open interval 800
So I write this? (550,800?)
No
It is [550,800)
And to show it on the number line
If im not wrong it was represented by a black dot meaning that point is included and a hollow dot meaning that point is not included
Black dot => closed interval
Hollow dot => open interval
And draw a line between those two points
To represent the value
Of w
Okay
@neat gyro Has your question been resolved?
@neat gyro Has your question been resolved?
@neat gyro Has your question been resolved?
I figured it out
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Hello! Im not the best at math and I would like some help to learn how to solve it! Its the simeltemions equations im not sure if i wrote it correctly but yeah.
If someone can just help me get through one of them and teach me how too that would be lovely!
So one of the equations are:
y = 2x + 1
y = -x + 2
There's a concept in mathematics about equality
If two things are equal to the same thing, then those two things are equal to eachother
In your case, the two things are 2x+1 and -x+2, and the same thing is y
That is, 2x+1 and -x+2 are both equal to y, so it will follow that 2x+1 and -x+2 are equal to each other
Im not sure i completely understand? Hm
Well im just overall confused in how to solve it
Sure. We're trying to find an x and y value that will satisfy both equations. Does that make sense?
that i understand
yeah i should be able too not too sure tho ive done something similar
Something similar?
yeah things like x + 5 = 6x stuff like that
im not sure if it is the same thing
sorry i aint the smartest but im trying to become it 🥲 Ive got to start somewhere
No worries
Okay we'll work on this because the strategy will actually be required to solve your problem
To solve x+5=6x, we need to find a value for x such that x+5 and 6x come out to the same number
this is x = 1 right?
Good. Then you have everything you need to solve your problem
I trust you. You're fine
alright then! :D
soo what next?
What you need now is to understand this idea
It's basically the idea that equality is transferable
If A is the same as B, and B is the same as C, it must be that A is the same as C
I understand that
Cool. So we will use that in your problem
Alrighty
I described it here
Does that bit make sense?
uhh yeah they are the same or equal correct?
exactly
or well they arent the same but they equal to the same outcome right?
Yeah that's a good way to think about it too
alright i get it
In general, yes, they are different things, but you want to find the specific value for x that makes the same, or makes it so they both get to the same outcome, as you said
So do you think you know how to solve it now?
hmm yes probably yeah ill try and solve it
if i cant figure it out can i come back here?
yes
Thank you very much! :D
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What is wrong 😭 answer (1,-1)
"by using Cramer's rule find s.s for each:"
You went from a1 a2 to c1 b1
In the matrix
It needs to be consistent
So meaning you changed it from a2 to b1
Instead of keeping it a2
If that makes sense
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Help, this server is unavailable
@ Helpers
hm
lol
whats wrong with the server
lmfao
shuwu-chan haii
!show
Show your work, and if possible, explain where you are stuck.
Toby

!nosols
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.
.coose
what the hell is this
differential geometry
whys this so pixelated. @pseudo hinge help
Zoom in
Is it still pixelated?
yes.
zoom out
Also you can only have so much resolution on an image with this much detail
And I'm sure TeXit doesn't want too much resolution since that would take more time to send
!help
Please read #❓how-to-get-help
<@&1091183017051050074>
Oh fuck it's pingable.
lol
@jaunty mural Has your question been resolved?
!help
Please read #❓how-to-get-help
Stick to your own channel
ban this mod pls
Do not challenge my
power. I don't know how to do the command, and nothing is showing up when I type, /, but I'm very confident I have it.
mod abuse
@jaunty mural Has your question been resolved?
<@&1091183017051050074> this user is spamming here
this annoying person
@jaunty mural Has your question been resolved?
Since when have any of you been mods
lol
@jaunty mural Has your question been resolved?
\ban DerpZ#9141
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do you know the formula for youngs modulus
hi
sorry, is it alright if i @ u tomorrow
my brain is too tired rn
i’m going to sleep
you can if you want, i cant guarantee ill be available though
thank u!
i’m sorry again, thought i would be able to do math rn but i need sleep
no worries
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Hi there. I have a question on some conceptual stuff from vector calculus. I'm confused on how many dimensions are for a function like f(x,y,z) = x^2 + y^2 - z^2
Is this 3 dimensional?
If it is 3 dimensional, what is f(x)=x^2?
It would be in 4 dimensions because the function is a function in 3 dimensions (3 variables) that outputs in the 4th dimension. Kinda difficult to conceptualize 4 dimensions intuitively tho
Ok, thank goodness. I was getting so confused because chatgpt kept telling me it was 3 dimensional. lol
😂
so the gradient of a function like f(x,y)=x^2+y^2 is (2x) i + (2y) j
Is there a way to visualize this?
it's a function from R^3 -> R, so the domain is 3-dimensional
the graph is 4-dimensional, because it's a subset of R x R^3
Oh I see. Thanks!
Oh a contour plot, yes
And you'll find that the gradient is always perpendicular to the level set
Oh ok. I'll check it out. Thanks 🙂
I think the gradient would look something like a V or an X shape of some sort since the graph is a circle which has decreasing slope on the right, the tangent line at the very top has slope 0, and then starts to increase is slope.
You could put it in geogebra and mess around with the visuals to get an idea
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,rotate
This is what i have so far for this problem
I cant figure out how to go from xn = 2^3 (xo)+(1+2+4)
to getting the closed form
Your teacher has a skill issue
Lmfao my Actual teacher gives us extra credit for submitting homework if we do it in LaTex
you should do it in latex
im just tryin to do the PROBLEM
whats your guess for the closed form? is this it?
no I havent got the closed form yet I need to get from having x0 to just n
well x_0 = 1
but I dont know how I go from x0 to like 2n-1
so just substitute
well theres alot more to do than that
yes
it probably is
I mean I dont know how to write that formula correctly but I can see its increasing by a power of two so does the front of the formula\
im noticing something here
do these numbers look familiar to you?
1, 3, 7, ...
almost like 2, 4, 8, ...
@robust crater say it were $x_n = 2x_{n-1}$
jan Niku
can you tell what closed form youd get out?
idk im just trying to nudge you into the answer
I actually wrote the formula for this earlier as 2^n+1-1 n=0
for a seperate problem
for this sequence
huh?
do you recognize this sequence?
yes
so whats the closed form
2n-1
what class is this for
Discrete
yes
it doesnt matter where you got the answer
the proof is what matters
you still have to do strong induction
He wants to find the the closed form - plug it into the recursive definition and simplify and check it works for the initial condition
and to skip the induction
because were covering induction in this chapter not the one this assignment was assigned in
I want to show how to get closed form because im probably going to have to reduce to closed form on the test but then from there I need to simplify the closed form and check initial
could you not just use the normal geometric form here?
to be honest its been years since ive done one of these the 'proper' way so im a little rusty but
wouldnt you just recognize its geometric
so isolate the n-1 term
Im not sure what that is im sorry this book is literally the worst thing ive ever seen
lol
there's 1 single example for this in the entire book
and that also includes the only explanation of this
oh man then were gonna have to learn together
heres what i remember is like
you do a few terms
I literally have the answer on chegg rn
you recognize the form of the sequence
and all the steps
its usually geometric or arithmetic
I just have no idea what im looking at and im trying to learn it not just rip it off
I think its arithmetic
chegg is fantastic
arithmetic sequences have terms with a common difference
ah
geometric sequences have terms with a common ratio
which is x2
right
now how you handle that +1

i havent done this in this way in a long time
lemme see
so right now i have 2^3(x0)+(1+2+4...n) and I know its going to be a power of 2 closed form in some way
jan Niku
let $k$ be some integer up to n
jan Niku
jan Niku
jan Niku
I think youre going to a more complex place with this
you get $x_n = 2^n - 1 + 2n$
jan Niku

this seems to be about where I was mentally
wait
both sides are a factor of 2 one is just being sequentially added
when N>=1 does that mean x0=1 or that you start at x1?
or does that mean the pattern grows
or that n will always be greater than 1
jan Niku
its discrete math
Ooooh
do you remember

Heya i liked it tho
When youre helping someone feel free to tag me!
$x_{n-1}$ right
jan Niku
say that $x_{n-1} = rx_{n-2}$
jan Niku
but thats a lie 
My brain auto erases a lot of stuff once a course is over lol
my brain auto erases everything directly after the class ends
and my teacher uses his power of autism to infodump like a madman without actually SAYING anything useful (He's a great person though)
behold some of his notes
yea ive had teachers like this before lol
I just need to know how to replicate getting the closed form for the test
I can do the rest
my 2^3(x0) nonsense?
jan Niku
i got sick and got behind a whole month and i have until my teacher wakes up to get caught up
this might be why this person is using that formula
for the sum
now that i think about it
x_0 is 1 right
so that x_n is just
2^n plus 2^n-1
thats partial sum of a geometric sequence
In this video I show how to derive the formula for the partial sum of a geometric sequence. I go over concepts such as geometric sequences, the common ratio ...
so $x_n = \sum_0^n2^i = \frac{x_0(1-2^n}{1-2}$?
jan Niku
yea, it works
jesus
jan Niku
does this make sense?
uhy
Uh*
start from like
well you can get here algebraically
you dont have to know anything
start from $x_n = 2x_{n-1}+2^0$
jan Niku
jan Niku
$x_n = 2(2x_{n-2}+2^0)+2^0$
jan Niku
should be +2^1
oh
not while its in the parens
do you see the pattern emerging?
try to write it out for x_n-3 if not
yeah each next power of two makes the inside variables grow by a power aswell
you should get $x_n = 2^3x_{n-3}+2^2 + 2^1 + 2^0$
jan Niku
you should get $x_n = 2^3x_{n-3}+2^2 + 2^1 + 2^0$
which is what I have now
take this process to its conclusion
you get $x_n = 2^nx_0 + 2^{n-1} + \dots + 2^0$
jan Niku
you get $x_n = 2^nx_0 + 2^{n-1} + \dots + 2^0$
eventually we can subtract enough to get x_n-somethign to be x_n-n right
we just have to repeat this process n-1 times
and well get this.
I guess this is just too large of a leap in the logic for my brain to follow
this doesnt account for +1 anymore
and x_n-5
it does
where
it just makes no sense period
reading this is like staring into a foglight
i dont believe you
since you reproduced these results basically
before we even started talking
im just trying to make you believe it
2^n(xn-1) gets what power the first two is
you have to feel it as counting down
what is this menagerie right here
what if i wrote it this way
jan Niku
how about
i just got it
$x_n = 2^nx_{n-n} + 2^{n-1} + \dots + 2^0$
jan Niku
but you needed a -1 in yours
its just a very very ugly version
and not the closed form
no no
its the same as mine but my version is ugly
but you need to believe this
I understand it
do you believe $x_n = 2^nx_0 + 2^{n-1} + \dots + 2^0$
its just not the closed form
jan Niku
jan Niku
should be 2-1
and 2n-1+1 is the closed form
stop
it doesnt prove anything
it should be +
please we have to finish this haha
i have to go to bed
well really i wanna take a sleeping pill
nah i want you to get it
I just cant convey my getting it to you because I dont get it but I understand what we're reaching at
I dont know what that is
if you arent using that you have made a mistake
it wasnt taught to us
bro flew through this at mach 12 and it will only show up 1 time
it just says
if you take some number
say 5 right
and you take
okay 5^4 + 5^3 + ...
all the way down to 5^0
what do you get
factorial?
well there was no 5^5
series because its a sum
and geometric because each term of the sum differs by that ratio
I was confused by us interpreting the formula as one that grows out
so we write $r^n + \dots + r^0 = \frac{1-r^n}{1-r}$
jan Niku
this is the known form
(really theres an initial term piece here but its not important for this problem)
well we have
$x_n = 2^n + \dots + 2^0$
jan Niku
and $2^n + \dots + 2^0 = \frac{1-2^n}{1-2}$
jan Niku
then $x_n = (-1)(1-2^n)$
jan Niku
how tf does the fraction become -1(1-2n)
geometric series arent covered in this chapter
until AFTER
this problem
this problem isnt meant to fuck with all this
well then i have no idea man
ones later will be designed for it
Im tellin ya i think I got what we're getting at
okay
I appreciate you getting me here
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Help
Question b, isnt supposed to be 30cos22.4?
Why is it written 30sin22.4
Nvm
Book error
.close
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May i know how to solve this matriks use gauss elimination ,i got stuct in here
LU Decomposition using Gauss Elimination method of Matrix calculator - Online LU Decomposition using Gauss Elimination method of Matrix calculator that will find solution, step-by-step online
try this
step by step solution of gauss
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how do I find the mixed 2nd order partial derivative of an implicit function?
I managed to find $\frac{\partial z}{\partial x}$ and $\frac{\partial z}{\partial y}$ but I don't know how to proceed from there
mesmeriSe
I used the implicit function theorem (?) thing,
$\frac{\partial z}{\partial x} = \frac{\frac{-\partial F}{\partial x}}{\frac{\partial F}{\partial z}}$
mesmeriSe
take the function and take $\frac{\partial}{\partial x}\frac{\partial}{\partial y} z$
right i thought so but it doesnt work
Jester
oh
so i got $\frac{\partial z}{\partial x} = -1+xe^{-(2x+2z)}$ which I confirmed is correct
mesmeriSe
but if i were to take partial y of that, wouldn't it be 0?
now if you take partial y of that you get 0 which is the answer to the second
yeah
mesmeriSe
oh well because your first differntation is not correct
you are taking partial z / partial x
i think it's correct, and the solution says this too
oh
isnt that what i want to be doing?
i take partial z/ partial x. Then I take partial y of the result
oh i see where you went wrong
??
when you take the partial of y you forgot partial z / partial x
because z is not constant, only x is
ohhh and to take partial z/ partial y we have to do it implicitly so
$\frac{\partial^2 z}{\partial y\partial x}=\frac{\partial}{\partial y}(-1+xe^{-(2x+2z)})=\frac{\partial}{\partial z}(-2z)xe^{-(2x+2z)}=-2\frac{\partial z}{\partial y}xe^{-(2x+2z)$
mesmeriSe
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
yeah
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We construct an acute triangle ABC with the three heights intersecting at H. Prove that HA+HB+HC<AB+AC
I cant use any trig or pythagoras, just triagular theorems (except the above)
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Currently stuck on a problem in number theory. The problem is as follows:
\\
"A theorem in number theory states that if $a$ and $b$ are positive integers and $p$ is a prime number that divides the product $ab$, then $p$ must divide $a$ or $p$ must divide $b$. From this theorem, it follows that:
\\
(a) If $p$ divides $ab$ and $p$ divides $a$, then $p$ does not divide $b$. \
(b) If $p$ divides $a^2b$, then $p$ must divide $a$ or $p$ must divide $b$.\
(c) If $p$ divides $a$ and $p$ divides $b$, then $p$ divides $ab$.\
(d) None of the conclusions (a) through (c) follow from the theorem."
\\
I am having trouble determining which of the options is true. I initially chose option (c) but I was told that the correct answer is actually option (b). I am unsure why this is the case.
dgh
b and c both seem right but you have to choose option that follows from theorem
So we can see that a and b are both coprime right? Because they only have the number 1 as a common divisor?
how?
nvm
but (c) is just https://en.wikipedia.org/wiki/Euclid's_lemma
Can someone explain how (b) is true?
A theorem can also be applied multiple times in a row. Feel free to split cases
@quartz salmon Has your question been resolved?
Could you elaborate on that
Either p divides a^2 or p divides b
Apply the theorem again on p | a^2
c is not euclid's lemma, euclid's lemma is the theorem we've been given
c is completely obvious, in fact you barely need any of the hypotheses: if a divides b, then a divides bc, for any a,b,c
So c is incorrect because it’s just restating what we’ve been given?
it's not restating what we've been given
it's "incorrect" in the sense that the statement is true, but it doesn't really follow from the theorem we've been given, it's true for completely unrelated reasons
whereas euclid's lemma, the theorem we were given, is actually useful in proving b
(a is false so it definitely doesn't follow from the true theorem we were given)
...i mean, how would you prove c?
We would break it down
Instead of a^2 b
We write aab
Then it follows that p | a^2b
From p | a
...what is this a proof of?
Of euclid’s lemma
why are you proving euclid's lemma?
...what is euclid's lemma? what's the actual statement?
We are confirming it’s true by choosing an option that is a consequence of its validity
...i'm not sure what that means but i don't think it's what the question was asking for
Okay well I’m not sure what you’re asking me for
I got the answer already anyway
.close
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...i'm not convinced you do have the answer but ok then
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I'm working on a question and was wondering if there is a way to express this without using the summation operator. if possible, I want to do it on my own but just wondering if there is a reasonable way to simplify it. Thanks
$\sum_{k=1}^{m} \frac{k-1}{n} (-\frac{1}{n})^{m-k}$
PerpetualOwl
like find an expression that equals to that or?
do you have any exemplars
of m and n? like they are positive integers
yeah don't spend too much time on it just wanted to know if there is something i'm missing
let's see what you've done
$(-\frac{1}{n})^m\sum_{k=1}^{m} \frac{k-1}{n} (-n)^{k}$
PerpetualOwl
this follows
but then the issue of n^k being mixed with k persists
$(-\frac{1}{n})^m\left(\sum_{k=1}^{m} \frac{k}{n} (-n)^{k} - \sum_{k=1}^{m} (-n)^{k}\right)$
PerpetualOwl
uhhh
there
So what you wanna notice is
You got a nice a geometric series
So obv you know a geometric progession can be generally expressed as
yeah
ye and what you basically are finding is an expression for sum a_i
So if you just compare what you have in the summand
to a_mr^(n-m)
Can you express it like that
and there's like only one way to do that
are we typing random things in latex
no
okay let (k-1)/n be equiv to a_m and -1/n be equiv to r and m-k be equiv to n-m
let's express a_m as a non fractional coefficient
and like you said n is some arbitrary constant
we could apply summation distributive law
take the constant out
blackboard (double struck) N sub (subscript aka suffix) 1 is the set of natural numbers from 1 onwards, equivalent to the set of positive integers, some authors define natural numbers including or excluding 0
are you following me or you confused
sure makes sense, the k and n^k is still an issue
ok
$\sum^m_{k\in\mathbb N_1}\frac{k-1}n\left(-n^{-1}\right)^{m-k}=\frac1n\sum^m_{k\in\mathbb N_1}(k-1)(-n^{-1})^{m-k}$
omfg
cool
now let's focus on the RHS
particularly the summand
$\sum^m_{k\in\mathbb N_1}(k-1)(-n^{-1})^{m-k}$
what can you express this as?
uhhhh
you can multiply out the k - 1 into two summations and the one with the -1 has a solution
what
let's still work with a single sum
and keep on the geometric series track
\begin{equation*}
\sum^n_{k=1}ar^{k-1}=
\begin{cases}
a\left(\frac{1-r^n}{1-r}\right), & r\neq1\\
an, & r=1
\end{cases}
\end{equation*}
obviously if you know your summation rules, idex shifting and all that
that's what i want you to apply
summation rules and geometric series type shi
yup
$\sum^m_{k\in\mathbb N_1}(k-1)(-n^{-1})^{m-k}=\sum^{m-1}_{j=0}j\left(-n^{-1}\right)^j$
makes sense
honestly there's many ways to do this but let's continue down this path
To evaluate the sum we differentiate both sides of the equation
$\dv{x}\sum^{m-1}_{j=0}x^j=\dv{x}\frac{1-x^m}{1-x}$
and ye more geometric series rules which you can prove for good practice
$\sum^{m-1}_{j=0}jx^{j-1}=\frac{mx^{m-1}(1-x)+x^m}{(1-x)^2}$
thats actually a very interesting way of approaching it
Ikr i hope harvard gives me a full time scholarship
let x=-n^{-1}
and ye
3 am
goodnight cuh
cya xd
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why the value of tan x and sec x is different?
Why would you expect them to be the same?
tan is opp/adj and sec is hyp/adj
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Hey.
Somone can help mee
Interval
start
10
11
12
13
14
14,5
15
16
Interval
done
10
11
12
13
14
14,5
15
16
hyppighed
18
29
45
40
16
11
25
16
frekvens
0,09%
0,145%
0,225
0,2%
0,08%
0,055%
0,125%
0,08%
sum frekvens
0,09%
0,235%
0,46%
0,66%
0,74%
0,795%
0,92%
1
Could you translate this please?
its like this
ohh yea
Interval
10-11
11-12
12-13
13-14
14-14.5
14.5-15
15-16
16-17
Frequency
18
29
45
40
16
11
25
16
frequency
0.09%
0.145%
0.225
0.2%
0.08%
0.055%
0.125%
0.08%
sum frequency
0.09%
0.235%
0.46%
0.66%
0.74%
0.795%
0.92%
1
Hmm
Frequency
Relative percentage
Cumulative percentage
You have the separated columns of the table
yes
Yes, but what do I do now?
Yes, but what do I do now?
@latent bloom
<@&286206848099549185>
this good?
Hallo
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draw R
the theta and r bound should become clear
then use the substitution r^2 = x^2 + y^2 into the integral
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-Znar
What do you mean it doesn’t have an inverse
for it to have a inverse, $2x^2 + 6x$ needs to be injective, but clearly $2(0)^2 + 6(0) = 2(-3)^2 + 6(-3)$, hence it doesn't have an inverse
The Universe
Well the inverse just isn’t a function
Injective means every output is mapped by at most 1 input
You can have inputs with no output or outputs with no inputs
injectivity means that \
$f(x) = f(y) \implies x = y$
The Universe
Because it’s a quadratic
Well, a non degenerate quadratic to be specific
All non degenerate quadratics
The Universe
A degenerate quadratic would be 0x² + 2x + 1
Yeah it’s a quadratic by name but not really
Well…
Hence non degenerate
Like if you put 3 points on top of another they can still form a triangle
But it’s just a degenerate triangle
f(0) = f(-3) = 0
So this is not quite right
I meant yea the inverse would be undefined for certain values
Like this
I know it’s only 1 mark so you probably don’t need much detail
f is not bijective and thus does not have an inverse,
f(0) = f(-3) but 0 ≠ 3 (a requirement for injectivity)
Look at f(x)
Bijective means it’s also injective means only 1 input can map to 1 each output
Which is what this means
But in f we found x=0 and x=-3 both these inputs map to 0 but are not equal to each other
Yes
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first thing to look for when factorising is whether all terms have a common factor
and if so, factor that out first
oh hang on
then this is used if its ax^3-b
or something
correct me if im wrong
@calm hedge Has your question been resolved?
because
i see people taking out a third power
like similar to the example i did before
i gtg now, thanks for your help
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Question 15
What is this graph called
I’m guessing the transformations are it’s up 30 and a horizontal dilation of 2
But I’m not sure
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Hi did I get this right?
I'm second guessing myself because the original vector is [ v1 v2] and adding any arbitrary vector could be a subspace
I think it is
Since the x value can be anything we don't need to worry about addition or multiplication taking it out of the subspace
And the y coordinate is never affected
It being non empty is trivial
Wait sorry I'm wrong adding two of them will make y = - 10
So you're right
Ahh ok - yeah that's what I thought since the 0 vector is not included in {x, -5}
is that a good reason too?
@sick mirage Has your question been resolved?
@sick mirage Has your question been resolved?
yes it is
it is a subspace?
no
it is a good reason
4/5
3rd quad one is wrong?
5th one
also doesn't contain 0
+3 makes it an affine space, which isn't a subspace (an affine space is of the form a + E with E a vector space and a a vector, and therefore is only a vector space if a = 0)
I think I understand - so fails the Identity test?
if you call it that
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Closed due to the original message being deleted
@gusty mason you fucked up and deleted your original message, now you need to abandon this channel and pick a new one.
Yeah I know I'm typing the latex of my question
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No I think you're okay
i got it the other way around and got it wrong






