#help-13

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sweet ridge
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But

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Imma trying to conclude my understanding in these drawing...
Anything wrong?
Its about set by the way

kindred storm
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You didn't label A and B in the second one.

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If they're the smaller two, then it's the combination of the circles, not including anything outside the circles.

kindred storm
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Yes. You've labelled the union as some elements outside of A and outside of B.

sweet ridge
#

Ogey (????)

mild sundial
#

It needs to be like this

kindred storm
#

The union doesn't include anything outside of A or B, so you probably shouldn't label the section that includes things outside A or B as the union.

mild sundial
kindred storm
#

No, that's also wrong.

mild sundial
mild sundial
kindred storm
#

You're labelling lots of elements that aren't inside A or inside B as being in the union.

mild sundial
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when did i label

kindred storm
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You have a square.

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You labelled the square as the union of A and B.

mild sundial
#

that's a way of showing it

kindred storm
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The square contains lots of elements not in A and not in B.

mild sundial
#

yes

kindred storm
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That's why it's wrong.

mild sundial
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a n b sets belong to a universal set wym

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I'm correct.

kindred storm
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You're labelling the universe as the union, when it's not.

mild sundial
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i ain't labelling it as a union

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I clearly wrote

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a U b

sweet ridge
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Ill sit for a while trying to understand what is not my native language

kindred storm
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You said A U B underneath a square, meaning that the square is A U B.

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The square isn't A U B.

mild sundial
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we r clearly speaking about set a and b

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so a U b makes sense

kindred storm
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I have no idea what you're talking about.

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A U B doesn't mean something that also includes A U B. It means something limited to exactly A U B.

crystal raptor
#

You can't just draw two unshaded overlapping circles and then write A U B near it. You need to shade or properly indicate which part is A U B

kindred storm
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You didn't limit it in any way to exactly A U B.

kindred storm
#

You didn't shade A U B.

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You didn't indicate in any way what A U B is.

mild sundial
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bruh.

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okay now I get where u going

kindred storm
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You merely labelled a rectangle as A U B, when that rectangle includes more than A U B.

mild sundial
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fine but I was just showing him u need to intersect the sets

sweet ridge
#

Okay...
So like...
U make a first circle...
Then it filled with 2 circle only "a and b"
So the first circle called union?

kindred storm
#

The union is the combination of all elements in A and in B.

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If it's in A, it's in the union. If it's in B, it's in the union.

sweet ridge
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So we cant draw it with circle???

kindred storm
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The shaded area is A U B.

sweet ridge
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Okay....

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Even its seperated, it will be called union if it's told to be it?

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Ummm

kindred storm
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If they're separated, there's just no elements in the overlapping part.

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They should be drawn overlapping to be more general.

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Overlapping doesn't mean the overlapping part contains any elements.

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But if you draw them apart, you're not handling situations where they both contain the same element.

sweet ridge
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So overlapping them to make it look more "united"?

kindred storm
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No, it's to work for all sets.

earnest radish
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seeing a face

kindred storm
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The sets that don't contain any common elements will merely have nothing in the overlapping part.

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So, it can handle all situations.

fervent jackal
kindred storm
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But if you don't overlap them, you're not covering the situation where they contain any common elements.

fervent jackal
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we make it overlap to make it more general

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because most cases two events have an intersection

kindred storm
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We're talking about unions.

fervent jackal
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Ik

kindred storm
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If you're trying to handle all possible sets.

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If you're drawing it for two particular sets, you can do otherwise.

sweet ridge
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Learning math

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Ogey...

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Im starting to understand

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Btw thank you very much ! @kindred storm @fervent jackal @mild sundial

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I hope we meet again!

kindred storm
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No problem.

sweet ridge
#

.close

cedar kilnBOT
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ionic urchin
cedar kilnBOT
ionic urchin
#

extremly lost

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can someone help

gentle flower
#

looks like a trig substitution problem

ionic urchin
#

wait heres a better picture

ionic urchin
tropic oxide
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u := arccos(x) suggests itself

ionic urchin
tropic oxide
#

the substitution u := arccos(x)

ionic urchin
#

yea ion think im that ahead bro

cedar kilnBOT
#

@ionic urchin Has your question been resolved?

raven shard
ionic urchin
#

i missed that class

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prolly should learn that or can yall jus help

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ill learn after too

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frail cosmos
cedar kilnBOT
frail cosmos
#

Stuck in the first one I'll translate it

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A, B, C and D are points on the circle
AB and CD meet together at point F.
<DAC=<DBC
<ACD=<BCD
Prove that DC is a diameter (already did)

Prove that AB is vertical to CD

cedar kilnBOT
#

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cedar kilnBOT
#

@frail cosmos Has your question been resolved?

frail cosmos
#

<@&286206848099549185>

cedar kilnBOT
#

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frigid hemlock
#

,

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jovial glacier
#

I have 8 coins, and I will pick 2 of them and add their values up. What can I set the denominations of the coins to be so I can get the most consecutive values starting from 0? (With one of coins being 1, and another coin being 0)

jovial glacier
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I know the maximum I could theoretically get would be 36 or (8 * (8 + 1)) / 2. I solved it through a brute force search and got 0,1,2,5,8,11,12,13; which can cover every value from 0 to 26. How can I solve it without checking all 2 billion combinations?

#

0,1,2,3,4,5,6,7 can do 0-14
0,1,2,5,7,10,11,12 can do 0-24, which was the best I could come up with by guessing

frail thistle
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i'm a little confused by your description of the problem, because assuming you can't pick up the same coin multiple times 0, 1, 2, 5, ... , 12 cant do 4

cedar kilnBOT
#

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jovial glacier
cedar kilnBOT
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latent hazel
#

Hi, is there any way to obtain 3x3 matrix that have 3 eigenvalues (1, 2, 3) and has 7 non zero elements?

floral terrace
#

!occupied

cedar kilnBOT
#

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sage forge
#

Hint: You can choose A_12=A_13 = 0 and A_11 = 1

latent hazel
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I tried something simmilar but I am always stuck with a case that determinant is -1

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basically I do not know what to put in other places

sage forge
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Ok, do you know what the advantage of this choice is?

latent hazel
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no I do not

sage forge
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If we want to calculate the Ev we need det(A-x*1)

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Since there is only one non 0 entry in first row we can apply Laplace

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Ok?

latent hazel
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ok we have something like a polynom that needs to be zero

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in order to get zero as determinant and have eigenspaces when working out kernell

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but well I do not know what you mean by Laplace

sage forge
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Laplace method to calculate the determinant?

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If there is only one non 0 entry in a row the determinant can be easily calculated

sage forge
latent hazel
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no never

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I only heard about Sarrus

sage forge
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Ok, no problem. I don't have a lot of time explaining the method to you though

latent hazel
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Oh I see I believe Laplac is when you choose a line or column and you could calculate detminant as sum of sub determinants

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am I right>

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?

latent hazel
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we just call it differently

sage forge
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And here we go over the first row

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Great that you have it

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Can you apply it?

latent hazel
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yes

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now I have something like this [(1, 0, 0),(1, 2, 1),(1, 1, 3)]

sage forge
#

Doesn't work

sage forge
# latent hazel yes

Ok, since I am a bit in a hurry: If you applied Laplace for Det(A-x1) for the given entries you would get (1-x)โ€ข some polynomial

latent hazel
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ok thanks you helped me a lot

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I will try rest on my own

sage forge
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Ok, sorry that I couldn't explain in more detail. Good luck

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Now there are only 4 entries to worry about

latent hazel
#

ok I belive I will manage

latent hazel
sage forge
latent hazel
#

.close

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glossy sigil
cedar kilnBOT
glossy sigil
#

Where am I wrong

cedar kilnBOT
#

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glossy sigil
#

<@&286206848099549185>

cedar kilnBOT
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rancid pollen
#

Have you subbed in the initial conditions

glossy sigil
#

Yup

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I did. that first

cedar kilnBOT
#

@glossy sigil Has your question been resolved?

cedar kilnBOT
#

@glossy sigil Has your question been resolved?

bronze crag
#

@glossy sigil Where in your equations do you use 1.1million?

glossy sigil
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e^c=A

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=1.1million

bronze crag
#

so then what did you get for c?

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Normally you would expand "e^(.05t + c)" to "e^c * e^.05t"

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then you can just use a different constant: y= Ce^.05t + 1million

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that way solving for C is easier when you plug in your initial population: 1.1million = Ce^(.05*0)+1million

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(since e^0=1)

cedar kilnBOT
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cedar kilnBOT
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versed fulcrum
#

Hello

cedar kilnBOT
versed fulcrum
#

Does anyone know the second symbol name?

mighty drift
#

lambda, sigma, rho

versed fulcrum
mighty drift
#

lowercase yeah
Uppercase is the summation symbol

versed fulcrum
#

Oh I see

#

Thanks

mighty drift
#

it's also very frequently used to represent a permutation

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or in probabilities for the variance or standard deviation (std I think, not sure though)

dusty hazel
#

variance is sigma^2

mighty drift
#

yeah that's what I thought

versed fulcrum
#

๐Ÿ˜ฎ blobsweat

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.close

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placid plank
#

how does this work?

cedar kilnBOT
placid plank
#

is it just divided by log?

tropic oxide
#

no

#

"dividing by log" is an error so serious it's a real DROP EVERYTHING, THIS IS AN EMERGENCY situation

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log(x) isn't the product of x with something called "log"

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log is a function and not a number!

magic solar
#

10^LHS=10^RHS

tropic oxide
#

and here specifically,

log(x) = 0 => x = 1

tropic oxide
magic solar
#

Unless log refers to log base e

placid plank
#

.close

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tropic oxide
#

doorslam!

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maiden cloak
#

I don't understand this. why is W a subspace of Rn?

tropic oxide
maiden cloak
#

W is a set containing vectors of an equal amount to the dimension of R. each a is a coefficient of each vector. if if there are some a(s) that let you set all the vectors to 0, its a subspace?

#

whats the "for all i, 1 <= i <= m" part for?

cedar kilnBOT
#

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maiden cloak
#

<@&286206848099549185>

tropic oxide
#

ok so like

#

you have here essentially a system of linear equations

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a homogeneous one at that

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the statement is that its solution set is a subspace of R^n

maiden cloak
#

ok

#

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serene basin
#

why is the hessian the jacobian of the gradient, rather than the jacobian of the jacobian? i know that the jacobian is the generalization of the derivative for functions R^n to R^m, but for multivariate functions R^n to R^1 for some reason we use the gradient instead (the transpose of the jacobian). i am confused generally about why this transpose is necessary.

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inner solar
#

let rotation be defined as this

cedar kilnBOT
inner solar
#

how can i write this rotation in a form of matrix?

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(e_1,...,e_n) is standart basis

upper abyss
#

I'm not clear on the rotation that's happening here

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Oh wait, where we let e2 be fixed?

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We find the matrix for any transformation the same way:

  • Plug the basis members into it
  • The results we get form the columns of the matrix
inner solar
#

can it be like this? @upper abyss

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in each column i wrote mapping of that basis

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yes it is correct

#

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dapper imp
#

how do i solve this to the x1+x2+x3-b=0 form? (the topic is vectors)

is it 3x1-x2+x3-5=0 ?

dapper imp
#

arigatou

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wraith daggerBOT
#

sofficino9188

LaTeX source sent via direct message.
```Compilation error:```! LaTeX Error: Unicode character โˆˆ (U+2208)
               not set up for use with LaTeX.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.65 so $c+(1/n)โˆˆ
                   A$, which is absurd because $c$ is the largest of all the...

You may provide a definition with```
merry nebula
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merry nebula
#

.close

#

.close

cedar kilnBOT
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inner solar
#

Prove that if $A$ is a regular matrix, then $A^T$ is also a regular matrix, and its inverse matrix $(A^T)^{-1}$ is equal to the transpose of the inverse of $A$, i.e., $(A^{-1})^T$, where $A^{-1}$ is the inverse matrix of $A$.

wraith daggerBOT
#

Slowaq

inner solar
#

this isnt sufficient is it?

#

i did not show that A^T is regular matrix

#

how should i do that?

#

.close

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zealous niche
#

How do you solve this?

cedar kilnBOT
silver fable
zealous niche
#

mhm?

silver fable
#

That's just the definition of e

zealous niche
#

ye what about it

#

like

#

how do you know it's equal to e

#

@silver fable

silver fable
#

In general :

zealous niche
#

how do i prove it

silver fable
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primal stag
#

Can somebody help me find the time complexity of this Dijkstra algorithm implementation in python?




def dijkstra(graph, start):
    previous = {v: None for v in graph.adjacency_list.keys()}
    visited = {v: False for v in graph.adjacency_list.keys()}
    distances = {v: float("inf") for v in graph.adjacency_list.keys()}

    distances[start] = 0
    pq = PriorityQueue()

    pq.add_task(0, start)

    while pq:
        removed_distance, removed = pq.pop_task()
        visited[removed] = True

        for edge in graph.adjacency_list[removed]:
            if visited[edge.node]:
                continue

            new_distance = removed_distance + edge.distance

            if new_distance < distances[edge.node]:
                distances[edge.node] = new_distance
                previous[edge.node] = removed
                pq.add_task(new_distance, edge.node)

    previous_str = {str(k): str(v) for k, v in previous.items()}
    visited_str = {str(k): v for k, v in visited.items()}
    distances_str = {str(k): v for k, v in distances.items()}


    print("Previous:", previous_str)
    print("Visited:", visited_str)
    print("Distances:", distances_str)

    return



cedar kilnBOT
#

@primal stag Has your question been resolved?

dire geode
#

Or find a python server

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crimson sedge
#

(-i)^2 = -1

but

(-1)^2 = 1

how is this broken down please? because idk if I am right here, I deduced this for the 2nd equality: (-i)^2 = (-1^2) * (I^2) = 1 * -1 = -1 is this right?

storm seal
#

i is the sqrt of -1

#

So when it's squared the sqrt is cancelled out

#

(-1) squared is 1 because the negatives cancel out

crimson sedge
#

ahhhhhh thank you!

#

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restive leaf
cedar kilnBOT
cerulean sail
#

Interesting question catThink do you have any idea of how to start it off?

#

(did you try the hint they gave you?)

restive leaf
#

i tried replacing Q^T and Q from the hing with the given equality for Q

#

but I only got the transpose part to I + vv^T alpha

#

so it's still not the same as Q

crimson delta
#

alpha is a number

#

so you can just move it

restive leaf
#

i did Q^T = Q

restive leaf
#

i am trying to expand Q^TQ now

#

any ideas how to simplify this?

#

i got it

#

thanks

#

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tawny forge
#

R = {(n,|n| + 2) : n is an element of Z} is a subset of Z x N

tawny forge
#

I understand this as a relation. What im having trouble with is understanding is how a function can go from Z -> N

#

Z being set of intergers and N set of natural numbers

clever mango
#

Do you mean overall how can there be a function f: Z -> N

tawny forge
#

Well, I know in the set it mentions n can be integers and when you plug in an integer to |n| it will be a natural number

#

its just odd that after the set they mention is a subset of ZxN

#

could you still write that if y = n + 2 instead?

clever mango
#

I mean this is not because through this relation every element from Z relates to some element from N

#

not odd*

tawny forge
#

true

#

but if n is an element of Z why not just write its a subset of ZxZ?

#

because regardless, if you enter an interger for |n|+ 2 youre going to get a natural number

clever mango
#

well yes, you could write as well f: Z -> Z and it would be ok because Z contains N

#

its just.. if we know that every value that the function can have is positive then we would as well denote it as f: Z->N

tawny forge
#

gotcha, that makes sense

#

This answers my question, thank you

#

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normal thorn
#

I have done A but need B

cedar kilnBOT
uneven iron
#

Derivative equal to 0, study intervals between critical points

normal thorn
#

I cant get the derivative right though

#

You use product rule right?

uneven iron
#

Yes, but you don't need it

normal thorn
#

Dp/dt = -4.1sin(PIt/2.3)

uneven iron
#

wrong

#

Remember chain rule

normal thorn
#

Dp/dt = -4.1Pi/2.3 cos(Pit/2.3) ?

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#

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neat patio
#

How do you find the inverse derivative of this function at a?

dire geode
neat patio
#

but you need the value of f^-1(2) in order to use inverse function theorem

#

so I know I could set

#

2 = x^3 + 3sinx + 2cosx

#

but from here idk how to solve this

dire geode
neat patio
#

wait

#

no fucking way

#

I accidentally found the answer

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kindred bridge
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proper rivet
cedar kilnBOT
proper rivet
#

Hi, I am optimising the above with Lagrange but didn't get n in the system of equations. How do I solve then?

cedar kilnBOT
#

@proper rivet Has your question been resolved?

proper rivet
#

<@&286206848099549185>

dire geode
#

You're missing equations in the gradient

#

you only took partial with respect to m. you also need to for n

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crisp sand
cedar kilnBOT
crisp sand
#

ignore the pictures of work but i am pretty confused with how to approach this problem.

#

not sure if we need to use 2d forces in this or projectile motion kinematics

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crimson sedge
#

Help

#

Oh srry

stiff totem
#

the second vector having zero as its third component lets you rule out a bunch of the options

#

like, the first vector [1,1,1] would require having -1 copies of u, and the first two components obviously can't be reached using v

#

also one of the options is in a very similar form to your given vectors

#

yeah

minor ocean
#

kk ty, one more thing tho

stiff totem
#

this might depend on your textbook

#

but zero vector should be parallel to everything

#

if you define parallel vectors to be vectors with the same span

#

then they aren't

#

but that's rare

#

last one as well

#

well

#

actually, if "same direction" means parallel

#

then yes

#

if you have an alternative definition that may be wrong

#

that's why I'm asking

#

"direction" isn't really a standard term -- it could be different depending on the course

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#

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azure lagoon
#

can anyone help me with this

cedar kilnBOT
#

@azure lagoon Has your question been resolved?

stiff totem
#

complete the square on the denominator

#

the result should be an arctan integral or something similar

azure lagoon
#

.close

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crisp sand
cedar kilnBOT
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Please don't occupy multiple help channels.

dire geode
cedar kilnBOT
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spice light
#

how would you parametrize a cylinder x^2 + y^2 = 9 in cylindrical unit vectors?

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#

@spice light Has your question been resolved?

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@spice light Has your question been resolved?

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@spice light Has your question been resolved?

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flint python
cedar kilnBOT
flint python
#

Help with this question please

#

I got u=1-x^2+y^2

#

And v=-2xy

#

Is that correct

#

For part A

#

<@&286206848099549185>

valid tendon
cedar kilnBOT
#

@flint python Has your question been resolved?

flint python
#

So, the locus of Q when P moves along the line y=4x 16x^2โ€“8x^2=8x^2

#

For part b

#

@valid tendon

#

<@&286206848099549185>

tropic oxide
flint python
#

It was

#

.close

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mystic wren
#

so i must select which of steps are invalid in this attempt at showing that the equation has no real number solutions, but they all look right to me... ๐Ÿ˜ญ any help appreciated

mystic wren
#

im pretty confident that 1 and 2 are correct

vital wing
#

check step 3 closely

#

after step 2, we have
(xยณ - xยฒ + 1)(xยฒ + x + 2) = 0

what can we conclude about it?

mystic wren
#

both things in the parenthesis must equal 0? but i thought thats what they said uhhhhh

raw gulch
vital wing
mystic wren
#

0

vital wing
#

were both factors 0?

vital wing
mystic wren
#

:0

mystic wren
vital wing
raw gulch
mystic wren
#

wait where did the 0 and 2 come from?

vital wing
#

example

raw gulch
mystic wren
#

i forgor abt that

vital wing
#

-.-
you are not helping

#

yes, you're right
but that doesn't help if the asker cannot use it because step 4 ruins it

raw gulch
mystic wren
#

OH i seee what u mean

vital wing
mystic wren
#

as in, both factors do not need to be 0 in order to equal 0

#

yes

vital wing
#

that's it!

mystic wren
#

okk

vital wing
#

step 3 is the offender :D

mystic wren
#

what about 4 5 6?

#

it is a select all :0

vital wing
raw gulch
mystic wren
#

oo okay

vital wing
#

we must resolve the actual question before proving that the final step is incorrect
this time, the offenders are step 3 and 6

mystic wren
#

ok so 6 is wrong simply cuz theres a root

#

thank you for your help

vital wing
#

mhm

mystic wren
#

.close

cedar kilnBOT
#
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mystic wren
#

how does the claim get to the last part?

cedar kilnBOT
mystic wren
#

like why did the (n+1) turn into just n for the sequence 0,1,...,n

cerulean sail
#

a0 = 0 and an = n

#

So you have (0 + n), which is n catlove

#

If that's what you mean?

mystic wren
#

:0

#

ohhhhh

#

i thought the (n+1) turned into n, turns out its the a0+an that did

#

thanks!

#

.close

cedar kilnBOT
#
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cerulean sail
#

A pleasure OathLove

mystic wren
cedar kilnBOT
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uncut roost
#

I NEED HELP!

cedar kilnBOT
crimson sedge
#

try making the bases equal

#

so like, 9^(something) = 9^(something)

#

do you know how to turn the 3^(10x) into 9^(something)

uncut roost
#

here is the answer

crimson sedge
#

yea thats fine

uncut roost
#

what is happeneing in the answer

crimson sedge
#

answer my question though

crimson sedge
crimson sedge
#

do you know about the exponent identity $(a^b)^c = a^{b\cd c}$

wraith daggerBOT
uncut roost
#

no but i know now

crimson sedge
#

okay u should remember that, it is important

#

so like

uncut roost
#

okay ill write that down

crimson sedge
#

3^(10x)

#

think of 10x as the product b*c in what i sent

uncut roost
#

ohhhh

crimson sedge
#

i want you to seperate it into two

#

so that you can get something that gives u 9

#

so like

#

3^(something) = 9

#

what is something

uncut roost
#

10

#

2

crimson sedge
#

okay good

uncut roost
#

why do we need 9

crimson sedge
#

so 3^2 = 9

#

i will explain in a bit

#

so

crimson sedge
uncut roost
#

oh for the other side?

crimson sedge
#

so what should our c be?

#

like

uncut roost
#

5?

crimson sedge
#

almost!

#

you forgot the x

#

so 5x

#

[
3^{10x} = \p{3^2}^{5x}
]

wraith daggerBOT
crimson sedge
#

agreed?

uncut roost
#

yes

#

i agree

crimson sedge
#

okay so we get

#

9^(5x)

#

NOW the reason we did this is because

#

there is another exponent identity

uncut roost
#

wait

#

oh

#

nvm

crimson sedge
#

[
a^x = a^y \Iff x = y
]

wraith daggerBOT
uncut roost
#

ohhh

crimson sedge
#

if two numbers have the base, and are equal, their exponents are equal

#

note this down too

uncut roost
#

cancel the basses ees

#

bases

west dirge
#

science?

crimson sedge
west dirge
#

teach me

crimson sedge
#

!occupied

cedar kilnBOT
#

Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #โ“how-to-get-help for instructions).

west dirge
#

im form 1

crimson sedge
#

so taffy like

uncut roost
#

yes

#

now x = y

crimson sedge
#

[
9^{y-11} = 9^{5x}
]

wraith daggerBOT
crimson sedge
#

how does this simplify

uncut roost
#

what about the other equation

#

y-11 =5x

crimson sedge
#

wdym?

crimson sedge
crimson sedge
uncut roost
#

this is the other equatuoin

crimson sedge
#

yes

uncut roost
#

equation*

crimson sedge
#

i was about to get to that

#

so like

uncut roost
#

okay

crimson sedge
#

another important identity relating to logarithms, (this is their definition): [
\m{\log_a}{b} = c\Iff b = a^c
]

wraith daggerBOT
crimson sedge
uncut roost
#

y = x+1)^2

crimson sedge
#

yeah exactly

uncut roost
#

yay

crimson sedge
#

but remember

crimson sedge
crimson sedge
#

into y - 11 = 5x

#

what do uget

uncut roost
#

what

#

wdym

crimson sedge
#

you know that y = (x+1)^2

#

and you have a y in y - 11 = 5x

#

which you can replace with (x+1)^2

#

still doesnt make sense?

uncut roost
#

why are we replacing it

novel seal
#

i had logarithm for exam today, it was nice

crimson sedge
#

because the issue is that to solve an equation we need to have one variable in it

crimson sedge
cedar kilnBOT
crimson sedge
#

you cant "solve" for a variable and get a number

#

but if you have 1 variable, you can solve for that variable and get a number

uncut roost
#

you combine them?

crimson sedge
#

y - 11 = 5x has two variables, so we cant get a value for x

uncut roost
#

yes

crimson sedge
#

(x+1)^2 - 11 = 5x has one variable, so we can get a value for x

#

does it make sense?

crimson sedge
uncut roost
#

yes

crimson sedge
#

ok great

#

so now

#

expand (x+1)^2

uncut roost
crimson sedge
#

yeah?

#

whats the issue?

uncut roost
#

you said it had 1

crimson sedge
#

one variable, which is only x

#

im not talking about the degree of the variables

#

it only has one letter-type

#

if you want me to say it that way

uncut roost
#

wait what are the 2 equations

crimson sedge
#

y - 11 = 5x
y = (x-1)^2

uncut roost
#

okay

#

see they both have x and y

crimson sedge
#

okay but thats what i am saying we can get rid of the y by substituting the second equation in the first

#

we can reduce the first equation from having two variables to only having one

uncut roost
#

5x+11 = (x-1)^2

#

?

crimson sedge
#

okay first of all, the 11 magically got an x and the 5's x vanished

#

and also, why is 11 negative?

uncut roost
#

sorry wait

#

okay now

crimson sedge
#

okay yes

#

thats correct

#

do you get what happened?

uncut roost
#

they are both y

#

so we make them eqaul

#

equal

crimson sedge
#

yes

#

do u see how we reduced our two variables to only 1? thats what you always want to do

#

if you have two or more equations and you are trying to solve for a variable, try to substitute one of the equations into the other, by solving for one of the variables, thereby reducing the amount of variables

#

okay great

crimson sedge
uncut roost
#

yes

crimson sedge
#

ok do it

uncut roost
#

x^2 - 5x -12

crimson sedge
#

also

#

hold up

crimson sedge
uncut roost
#

okay

crimson sedge
#

but why did you turn the (x+1)^2 to (x-1)^2 lol

uncut roost
#

i slept for 2 hours

crimson sedge
#

catThimc fair enough

novel seal
novel seal
#

accidentally

crimson sedge
#

oh okay sorry for that

#

so expand 5x + 11 = (x+1)^2

uncut roost
#

i dont understand

#

that is not what the answer says

crimson sedge
#

it is

#

exactly it

uncut roost
#

where

crimson sedge
#

they just, for some reason, retained the 2

#

divide both sides of 2(x+1)^2 -22 = 10x by 2 you get (x+1)^2 - 11 = 5x

#

which is the same as we have

uncut roost
#

oh i get it

crimson sedge
#

the 2 is totally irrelevent

uncut roost
#

they changed the other side

crimson sedge
#

i dont know why they retained it but oh well

uncut roost
#

okay i get it now

crimson sedge
#

ok

uncut roost
#

wait

crimson sedge
#

solve the quadratic

uncut roost
#

do you know the log rules

uncut roost
crimson sedge
#

yes, what about them?

uncut roost
#

i have to get to school

crimson sedge
#

understandable

uncut roost
#

thank you so so much qylo

crimson sedge
#

here

uncut roost
#

THANK YOU

#

i have to go now

crimson sedge
#

also the exponents' laws for good measure, because u said earlier u didnt know all of them:

crimson sedge
#

.close

cedar kilnBOT
#
Channel closed

Closed by @lone wigeon

Use .reopen if this was a mistake.

#
Available help channel!

Send your question here to claim the channel.

Remember:
โ€ข Ask your math question in a clear, concise manner.
โ€ข Show your work, and if possible, explain where you are stuck.
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โ€ข Type the command .close to free the channel when you're done.
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gray oasis
cedar kilnBOT
gray oasis
#

I'm taking Calculus. For A. we are to get the domain of the functions.

#

For C. I don't know what's the way to solve that because our teacher didn't teach it.

crimson sedge
#

is the top thingy irrelevent?

#

okay

#

is 'a' specified to you?

#

h(a^2+1) could fall into either of your function's cases

#

so we need to know if anything about a is specified

gray oasis
#

Nope. There's nothing more there.

crimson sedge
#

okay so i assume they want u to generalise it for both cases

#

alright i guess

#

lets start with $h(x) = \s{x-5}$

wraith daggerBOT
crimson sedge
#

what is h(a^2 +1) for this?

gray oasis
#

Sorry what?

#

Where?

#

Do I press the texit?

crimson sedge
#

uhhhh

#

what

#

im asking you a question

gray oasis
#

There's a bot that appeared

crimson sedge
#

and i want ur answer to it lmao

gray oasis
#

Or is that irrelevant?

crimson sedge
#

yes i compiled that

#

it shows u the math equations

gray oasis
#

Oh okay sorry I'm new here

#

It's loading hold on hehe ๐Ÿ˜…

crimson sedge
#

"lets start with h(x) = sqrt(x-5)"

#

thats what i said

gray oasis
#

h(a^2 +1) = sqrt (a^2 +1) - 5

#

is that right?

#

just substitute it?

crimson sedge
#

yeah but u r missing parentheses

#

sqrt((a^2 +1) - 5)

gray oasis
#

oh right sorry

#

how do i proceed from that?

crimson sedge
#

sqrt(x-5) if x <= 5?

#

but thats only defined for x = 5

#

anything lesser than that and it is imaginary

#

are u sure u wrote that correctly

hidden mural
#

she is not sure

gray oasis
#

I just copied it from the sheet

hidden mural
#

neither am cuz idk the question

gray oasis
#

wait lemme check

valid tendon
#

theres no wae its complex

gray oasis
#

that was our quiz earlier. I just sneaked to copy it to answer it for later because I didnt do well on the actual quiz

crimson sedge
#

i think u probably copied it wrong because the domain of h just doesnt include values lesser than 5

#

so

gray oasis
#

h(x) = { sqrt X - 5. if X <= 5
{ (X + 4)^2. if X > 5

find h(a^2 + 1)

#

i copied it right

#

i asked from my classmates

crimson sedge
#

was it supposed to be $\s x - 5$

wraith daggerBOT
crimson sedge
#

ask them if it is sqrt(x) - 5 or sqrt(x-5)

gray oasis
#

sqrt(x-5)

crimson sedge
#

okay thats just weird then

gray oasis
#

how come?

crimson sedge
#

try putting in x = 4 what do u get

crimson sedge
gray oasis
#

oh right it will be an error

crimson sedge
#

yes

#

this is ONLY defined for x = 5

#

so saying x <= 5 is just wrong

gray oasis
#

He didnt teach us how to evaluate that

crimson sedge
#

so i really dont know whats happening in there

gray oasis
#

I thought were just going to substitute it in 1?

crimson sedge
#

yes but the definition of the function itself is ambigious...

#

but whatever, i digress

gray oasis
#

what i did on my paper was to just substitue (a^2 + 1) in both equation

crimson sedge
#

yeah that should be it

#

its just where x is defined seems wrong, which is what i was commenting on

#

anyways we can work on the A's which are much less ambigious if you want?

gray oasis
#

yes please

crimson sedge
#

okay so $\ds \s{x^2-1} + \s{1-x}$

wraith daggerBOT
crimson sedge
#

lets consider each part of this

#

first of all the sqrt(x^2 -1)

#

do you know the domain of this?

gray oasis
#

no sorry

#

r we going to use the number line or the interval table there?

#

or they are not necessary?

crimson sedge
#

i mean we can do it however u wanna

#

ok i can work u thru it

#

so like the square root function can never have whatever is inside it be negative yes?

gray oasis
#

but it can be zero?

crimson sedge
#

yes

#

sqrt(0) = 0

#

so like

gray oasis
#

is any function still valid if it is zero?

#

0 can be a domain?

crimson sedge
#

what does that mean

#

yes that can be a part of a domain

#

why not

#

it depends on ur function

#

anyways

gray oasis
crimson sedge
#

,rccw

wraith daggerBOT
crimson sedge
#

yes

#

what about it?

gray oasis
#

one more question. im really confused about this.

#

0 can be a legitimate output? in finding domain of function?

crimson sedge
#

take the simplest function

#

f(x) = x

#

f(0) = 0

#

that is a valid input and output

#

there is nothing cursed about 0 that makes it not be able to be the input of any function

gray oasis
#

OOOHHH just the denominator that cannot be zero then?

#

of a fraction

crimson sedge
#

yeah

#

1/x, x can never be 0

#

f(x)/g(x): g(x) can never be 0
sqrt(h(x)): h(x) can never be a negative number

#

i hope this makes it clear

gray oasis
#

YESS

gray oasis
crimson sedge
#

okk great

#

so

#

[
\tss{for}\s{x^2 -1}: \q x^2 - 1 \ge 0
]

wraith daggerBOT
crimson sedge
#

im just describing what we said in mathematical terms

#

what i wrote is fine yes?

gray oasis
#

greater than or equal to zero right?

crimson sedge
#

yeah

#

anything not negative

gray oasis
#

yeah okayyy

crimson sedge
#

so i want u

#

to solve that inequality

#

find the values of $x$ that satisfies the inequality $x^2 -1 \ge 0$

#

do yk how

wraith daggerBOT
gray oasis
#

uhh

#

no sorry

crimson sedge
#

ok this will make ur life extremely hard for the next few questions

#

just a warning

gray oasis
#

๐Ÿ˜ญ

crimson sedge
#

but i guess i will try and help

#

so like

#

,align
x^2-1&\ge 0 \
x^2 &\ge {???}

wraith daggerBOT
crimson sedge
#

what is ???

gray oasis
#

1

crimson sedge
#

great

gray oasis
#

positive

crimson sedge
#

xo $x^2 \ge 1$

wraith daggerBOT
crimson sedge
#

how do u get rid of the exponent?

gray oasis
#

uhhh

#

im not sure

#

factor?

crimson sedge
#

hint: ๐Ÿซš

#

ok thats a bad joke

#

but just take the square root of both sides

gray oasis
#

i dont even get the joke ๐Ÿ˜ญ

#

was the hint a root?

crimson sedge
#

its because it has "root"

#

yeahh lmao ๐Ÿ˜ญ

gray oasis
crimson sedge
#

what is the square root of x^2?

gray oasis
#

x?

crimson sedge
#

not quite!

#

its |x|

#

are u familiar with what that means?

gray oasis
#

absolute value?

crimson sedge
#

yeah!

gray oasis
#

so always positive?

crimson sedge
#

and what about 1? whats the square root of 1

crimson sedge
gray oasis
#

1

crimson sedge
#

okay

gray oasis
#

if finding for sqrt of aything that is squared, just cancel both right?

#

the sqrt and square?

crimson sedge
#

[
x^2 \ge 1 \Iff \abs x \ge 1
]

wraith daggerBOT
crimson sedge
wraith daggerBOT
crimson sedge
#

so u should keep that in mind

gray oasis
#

okay

#

x and 1?

crimson sedge
#

hm?

gray oasis
#

oh wait

crimson sedge
#

im just like

#

trying to keep up my pace with u so u dont get lost

#

lmao

#

but are u fine with everything up until now?

gray oasis
#

is x^2 - 1 the same as (x-1)(x+1)?

crimson sedge
#

yes

#

it is

#

you could also solve it with what u r doing

gray oasis
#

its another method? ๐Ÿ˜ญ

crimson sedge
#

yea

#

we can uh

#

do that if u want

#

its all the same tho

gray oasis
#

can we try urs first?

crimson sedge
#

suree

#

so

crimson sedge
gray oasis
crimson sedge
#

ye do u understand everything

gray oasis
#

yes

crimson sedge
#

with it

#

sick

#

so

#

lets use our definition of an absolute value function

#

[
\abs x = \begin{dcases*}
x &if $x \ge 0$ \
-x &if $x < 0$
\end{dcases*}
]

wraith daggerBOT
crimson sedge
#

you know this right?

gray oasis
#

omg noo ๐Ÿ˜ฑ

crimson sedge
#

what? kongouDerp

gray oasis
#

really noo

crimson sedge
#

okay so

#

its really simple

#

what its saying is that

#

if x is bigger or equal to 0 then the value of |x| is just x

#

like |3| = 3

#

|4342424| = 4342424

#

is this fine by u?

gray oasis
#

yepp

crimson sedge
#

yeah so the second part

#

is saying like

#

if x is lesser than 0 then its equal to -x

#

sooo

#

|-3| = -(-3) = 3
|-3424324| = -(-3424324) = 3424324

#

the negatives cancel so u just get the number

#

does this make sense

gray oasis
#

so just everything under absolute is positive no?

crimson sedge
#

yeah

#

exactly haha

gray oasis
#

ok ok hehe

crimson sedge
gray oasis
#

yeah ๐Ÿ˜…

crimson sedge
#

okokok

#

so back to what we have

#

|x| >= 1

#

so

#

we can seperate it into two cases

#

[\begin{cases}
x\ge 1, \q x\ge 0 \
-x \ge 1, \q x < 0
\end{cases}
]

wraith daggerBOT
crimson sedge
# wraith dagger

this may seem confusing, but what i did is use this pretty much

#

ask if anything doesnt make sense lol

gray oasis
#

the second part still confusing hehe

crimson sedge
#

hmmmm

#

so like do u agree that a negative number multipled by a negative is positive always

#

-(-x) = x

gray oasis
#

yes

crimson sedge
#

yuh

#

so thats what its saying

#

its basically saying

#

if you have a number lesser than 0 (for example -3 )

#

then that number is equal to -x (so -(-3)) which is equal to 3

gray oasis
#

ahh omg i disregarded the ngative i the -x.

#

okok

crimson sedge
#

okk

#

so i hope this is fine now?

gray oasis
#

yes

crimson sedge
#

for $x\ge 1, \q x \ge 0$, i want you to find the intersection of both intervals

wraith daggerBOT
crimson sedge
#

intersection means like

#

the part they both have in common

gray oasis
#

how?

#

to find it?

crimson sedge
#

i want more than 0 apples, but i also tell you i want more than 1 apple, so in conclusion i want more than __ apple