#help-17

1 messages · Page 15 of 1

thin vale
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no

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positive definite matrix has x^T A x > 0

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for all x

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but you can test this by seeing if all eigenvalues > 0

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which C has

heavy plover
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sure then

thin vale
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B has >= 0

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so only semidefinite

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and earlier we decided B was singular because of eigenvalue of 0

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and C had all nonzero eigenvalues so it was nonsingular

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that is where we are at @fluid obsidian

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So now we want to find out what we know about B/C being either symmetric/orthogonal/diagonal

heavy plover
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symmetric orthogonal and diagonal are left

twin meteorBOT
heavy plover
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i mean you could solve for B and C

thin vale
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I am looking into symmetric

heavy plover
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then its obvious

thin vale
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poppylikecats

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could you agree/disagree with this for me

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if

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$B=S \Lambda S^{-1}$ then $B^T=(S\Lambda S^{-1})^{T}=(S^T)^{T} \Lambda^{T} S^{T} = S \Lambda S^{-1}$

heavy plover
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that does make sense

twin meteorBOT
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AustinU

thin vale
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So $B^T=B$

twin meteorBOT
#

AustinU

thin vale
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B is symmetric

heavy plover
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yes

thin vale
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okay

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when I do the same for C

heavy plover
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i think it works for C too

thin vale
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no

fluid obsidian
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Yes

thin vale
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but

fluid obsidian
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The yes is not for you no

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I was saying yes?

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"When you do same for C" , "yes?"

thin vale
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$C=S(\Lambda+I)^{-1} S^{-1}$ and if we transpose this we get$\newline$ $C^T=S(\Lambda+I)S^{-1} $

twin meteorBOT
#

AustinU

heavy plover
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seems to work

thin vale
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the inverse sign

heavy plover
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oh wait

fluid obsidian
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Wait

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Well why does the inverse sign go?

heavy plover
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it would still be inverse

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ur taking transpose

fluid obsidian
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It's a diagonal matrix

thin vale
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it would be

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inverse

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transpose

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so just inverse

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oh

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it stays

fluid obsidian
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Yes

thin vale
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so C is symmetric aswell?

fluid obsidian
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Yes

thin vale
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Left is orthogonal and diagonal

heavy plover
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for orthogonal you would have B(B^T) = I i think

fluid obsidian
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C is not singular , C is symmetric, C is positive definite

thin vale
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Do we know anything about the eigenvalues of orthogonal matrices?

heavy plover
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since B^T = B then B^2 = I

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if true then orthogonal

fluid obsidian
thin vale
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alright well then $B(B^T)=S\Lambda S^{-1} (S\Lambda S^{-1})^{T}$

twin meteorBOT
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AustinU

thin vale
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which is $S\Lambda S^{-1}S\Lambda S^{-1}$

twin meteorBOT
#

AustinU

thin vale
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which is $S\Lambda^{2} S^{-1}$

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so B(B^T) only equals I when B=I

heavy plover
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missing a squared symbol

fluid obsidian
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How ?

heavy plover
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on the lambda

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i dont think you could diagonalise I like that

twin meteorBOT
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AustinU

heavy plover
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unless lambda^2 = I

thin vale
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I didn't diagonalize it like that, that is just what B(B^T) is

heavy plover
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no i mean i dont think it can equal I

thin vale
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Agreed

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so B is not orthogonal

fluid obsidian
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B isn't orthogonal

heavy plover
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do the same for C

fluid obsidian
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C isn't aswell

heavy plover
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is that it

thin vale
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no

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still left with diagonal

heavy plover
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ah

thin vale
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diagonal matrices are orthogonal right? if normalized

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so

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not diagonal

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for both

fluid obsidian
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Well if it has to be orthogonal then the diagonal matrix in between has to be with ±1 diagonal entriws

heavy plover
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yes i think diagonal matrices are orthogonal

thin vale
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omg

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guys

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we got it right

heavy plover
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since you can make each row e1 e2 e3 etc when doing row reduction

heavy plover
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W

fluid obsidian
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Can you show the response

thin vale
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I've never been happier to get a linear algebra problem correct

thin vale
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thank you both so much for your help btw!

heavy plover
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np

thin vale
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this is the answer

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no working

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:|

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but that is what we got!

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so all is great in the world

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and it's a beautiful day

fluid obsidian
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Wait it's positive semidefinite?

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Oh wait sorry

thin vale
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yes that is what we decided earlier

fluid obsidian
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Saw for B

thin vale
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that was like the second thing we did

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alright alright alright

heavy plover
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we got it all

fluid obsidian
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I thought it was for C

heavy plover
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no B had a 0 eigenvector

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so we said semidefinite

fluid obsidian
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Yes

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I thought it was about C

thin vale
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this deserves some kind of party

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but, I have more problems to finish

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so hopefully I can do them, and I won't see you guys anymore tonight

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but I probably can't do them

fluid obsidian
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You are done for the day Austin

thin vale
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and I probably will see you later

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XD

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can't stop wont stop faf

heavy plover
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ill be here probably

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if its linear algebra

fluid obsidian
thin vale
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can I tag you? if I have another one soon poppy

fluid obsidian
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It's not a one sided relationship

thin vale
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it better

fluid obsidian
thin vale
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alright, thanks so much again guys. This was great to finally get finished

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cya around!

heavy plover
thin vale
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.close

vocal sleetBOT
#
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thin vale
vocal sleetBOT
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glad socket
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Yo I’m really confused with question 5. I have no clue what to do

lone niche
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that's enough info

sour cedar
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do yk slope-intercept form?

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i mean

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point slope forn

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form*

glad socket
lone niche
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slope intercept is cringe anyway

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point slope clears

formal rock
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Mood

sour cedar
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invalid opinions

lone niche
twin meteorBOT
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zfnQRZJT

lone niche
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you have a point and you know the slope m

glad socket
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ye

lone niche
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does that help

glad socket
#

ye i think i got it

lone niche
#

alr

glad socket
#

u can close now

vocal sleetBOT
#

@glad socket Has your question been resolved?

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violet lodge
#

How do u do this?

vocal sleetBOT
vocal sleetBOT
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@violet lodge Has your question been resolved?

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fathom hedge
vocal sleetBOT
fathom hedge
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how would you do this one

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im completely stumped

paper depot
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in a parallelogram, two of the vectors joining one point to another are the same

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or rather

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let me try to say this in a notation free manner

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if you take the vector joining two of your points, and the vector joining the other two points, and if you were lucky enough to pick them in the right order to make them two sides of the parallelogram and facing the same direction,

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then those vectors will be equal.

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your problem has the complication that you don't know which order to pick those points in.

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but there are only so many ways you could do that.

paper depot
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brute force maybe?

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theres uh. 12 ways to pick these?

fathom hedge
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wait that actually did work

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there are 6 possible parralel combinations

paper depot
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yeah 6

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my bad

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CD=EF
CD=FE
CE=DF
CE=FD
CF=DE
CF=ED

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these six

fathom hedge
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cd and ef, de and cf, and ce df

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I just did like cd = n * ef

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solved for x and z

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for each of the three

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noticed two had the same solutions

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so it must be those

vocal sleetBOT
#

@fathom hedge Has your question been resolved?

vocal sleetBOT
#

@fathom hedge Has your question been resolved?

vocal sleetBOT
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vocal sleetBOT
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Show your work, and if possible, explain where you are stuck.
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mossy sandal
vocal sleetBOT
mossy sandal
#

i figured the first one

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using distance formula

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i dont know how to find the equation

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i know the format is y = mx + c

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but idk how to find the y intercept (c) or slope

timber gale
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to find the slope rise/run. if youve found c anyways

mossy sandal
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from the question given

timber gale
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yeah im stumped on that

mossy sandal
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slope is x2 - x1/y2 -y1

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ig i can do that

timber gale
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hmm

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i think its perpendicular no?

mossy sandal
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it should be

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right angled isosceles

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triangle

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let me draw a diagram

timber gale
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yeah then you have the slope for that since the gradient for perpendicular is inversed

mossy sandal
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what..

timber gale
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I swear ive done this recently let me jog it up brb

mossy sandal
timber gale
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what in the diagram is that

mossy sandal
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the diagram

timber gale
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you didnt get point c tho lol

mossy sandal
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i made

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i didnt

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i just

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rough drew it

timber gale
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if you can find the slope of ab then you can find the slope of bc

mossy sandal
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bc?

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but wont it have a different slope

timber gale
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since its perpendicular hence the right angle

mossy sandal
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oh yeah

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what about the intercept

timber gale
mossy sandal
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i need some working for marks

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if it were up to me i wouldve used desmos for the entire thing

timber gale
#

let me work it out in a bit

mossy sandal
#

alr

timber gale
#

but you need to understand it conceptionally

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desmos will draw the graph for you. when you need to draw the graph yourself which is why your stumped here

mossy sandal
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i can still draw it by myself but

timber gale
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time?

mossy sandal
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i guess they dont take drawings

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you have to prove it

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prove that the y intercept is that

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this is a practice question

timber gale
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hmmm

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thats kinda icky the one i drew

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@mossy sandal the gradient for c is -2 i believe

mossy sandal
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bc?

timber gale
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yes since its perpendicular

mossy sandal
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does the sign change

timber gale
#

i have a question myself

mossy sandal
#

yup

timber gale
mossy sandal
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so you cant find the y intercept without any working?

timber gale
#

y intercept for what?

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bc?

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or ac

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what if there is no y intercepts...

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wait unless it intersects through the triangle i guess??

timber gale
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they just said an iscosceles has a 90 degree angle

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oh shoot it can

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im so goofy looking at the wrong but similar diagrams

mossy sandal
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whats c gradient

timber gale
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bc is -2

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mb i was just doing it ig

mossy sandal
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whats c gradient though

timber gale
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its the bc

mossy sandal
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gradient of line bc?

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ah

timber gale
#

i just didnt write b

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..

mossy sandal
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i see

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also why did u make 2/4 -> -1/2

timber gale
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you can further simplify gradients

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is 4/2 not 2?

mossy sandal
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it is

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but it became negative

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nvm

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i read one of the equal to thing as a negative sign

timber gale
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negative since perpendicular

timber gale
mossy sandal
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ab is 2/4

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so that means bc is

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-1/2

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right

timber gale
#

no

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AB is the 2/4 or the 1/2

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-2 is the BC which is perpendicular to it thus making the 90 degree angle

mossy sandal
#

wait

timber gale
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-2 x 1/2 = -1 thus perpendicular

mossy sandal
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if ab is 1/2

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wont bc just be negative of that

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because of the perpendicular law you mentioned

timber gale
#

yes thats why its -2

mossy sandal
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-2 is reciprocated

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you are supposed to reciprocate and switch the symbol as well?

timber gale
#

yes

mossy sandal
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ohh

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ok -2 is bc

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how can i use that for c

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actually wait

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i can probably use the slope to find where c is right

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but then how do u get intercept 😢

timber gale
#

which c

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just the vertex c?

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or you mean ac

mossy sandal
#

intercept

timber gale
#

which

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y or x

mossy sandal
#

y

timber gale
#

the question is

mossy sandal
#

in y = mx + c

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for the equation of bc

timber gale
#

does bc intersect?

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through b and just go through

mossy sandal
#

if it stops at point a no

timber gale
#

if so then the y intercept using the slope is 6

mossy sandal
#

ok so no y intercept at all

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for bc

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so its just

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y = -2x

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let me check the answer ke

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key

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nvm

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its -2x + 6

timber gale
#

lol i said 6

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🙃

mossy sandal
#

how do u get

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6

timber gale
#

the slope

mossy sandal
#

i kinda get it

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but how do u get the point exactly

timber gale
#

which point

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6 exactly?

mossy sandal
#

the y intercept

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yes

timber gale
#

rise over run

mossy sandal
#

like the working needed for it

mossy sandal
timber gale
#

-2/1 but im going up 2 and then 1 square or x over

mossy sandal
#

oh

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you did it like that

timber gale
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YES CUZ thats how the slope works lol

mossy sandal
#

theres probably a formula

timber gale
#

No

mossy sandal
#

to figure out at what point the y intercept is using the slope

timber gale
#

for what

mossy sandal
#

or not

timber gale
#

oiadh gaiohgih

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prolly.

mossy sandal
#

imagine if the slope was a decimal lol

timber gale
#

it wont be

mossy sandal
#

thats why im kinda concerned

timber gale
#

itll be a fraction

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Bro

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decimals can be fractions

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a slope is legit used as a fraction

mossy sandal
#

what if the point is far away

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from the axes

timber gale
#

you mean larger numbers?

mossy sandal
#

yup

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theres probably a formula at that point right

timber gale
#

yes you need to substitute and do algebra not a formula

mossy sandal
#

is there a source somewhere

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with those steps

timber gale
#

.

mossy sandal
#

not for this question but just samples

timber gale
#

wikihow.

mossy sandal
#

oh bruh

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its just

timber gale
#

or google

mossy sandal
#

make x 0

timber gale
#

yes

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if you have the equation>?

mossy sandal
#

actually thats for the whole equation yeah

timber gale
#

oh yeah im so dumb lol but yes

mossy sandal
timber gale
#

if you have the equation but just missing the y int

mossy sandal
#

maybe this has my answer

timber gale
#

just make x = 0

timber gale
#

or you tryna understand it

mossy sandal
#

without just drawing a line and calculating it visually

timber gale
#

the whole gdamn line uses the slope

timber gale
#

if you want to have it accurate you use the slope.

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rise/run rise goes up and run goes across

mossy sandal
#

oh...

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you just

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put the points into the equation

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and solve for c

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so the point at b is

timber gale
#

c or b

mossy sandal
#

uh

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any point that passes through the line

timber gale
#

yes you can always rearrange the formula or equation to find your missing points

mossy sandal
#

as long as we have the slope we can put the points

timber gale
#

YES B IS THE Y intercept

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m is the gradient

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thats all you need for a linear equation

mossy sandal
#

4 = 1 + c

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ok c is 3

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the y intercept is at 3

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so its y = -2x + 3

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wait

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it was 6 in the answer key

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wtff

timber gale
#

cuz it is 6??

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i think your confusing yourself at this point

mossy sandal
#

i am

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ok i'll just explain whats going on

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inside my head

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in y = mx + c

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to find c

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you can substitute the values of x and y of any given point on the line

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and the slope is -2 as we derived

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b is (1,4)

timber gale
#

..

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stop

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stop

mossy sandal
#

aaaaaaa

timber gale
#

let me explain

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to find y intercept

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wait let me think fo ra moment

mossy sandal
#

💀

timber gale
#

yeah ik

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yeah nah

#

@mossy sandal

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pls do your algebra again

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so the point is (1,4)

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equation is y=-2x+b ( we found m/slope yes slot it in )

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now add in the points

mossy sandal
#

oh...

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i took x + b

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completely forgot about -2x

timber gale
#

4=-2(1)+b

mossy sandal
#

RAHHSF

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43G

timber gale
#

b=6

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bruh

#

cmon man

mossy sandal
#

i dont practice maths

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i just get distracted every time i try to practice

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and then i always make mistaktes

timber gale
#

better start practicving maths or youll end up like me

mossy sandal
#

like this

timber gale
#

just 5 days ago i had no clue how to draw a linear graph aswell lol

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while my ass is doing functions

mossy sandal
#

well atleast i knew that

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💀

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alr thanks then

timber gale
#

but i had to grind like 20 chapters or so of math questions.

mossy sandal
#

its worth it ig

timber gale
#

and i have an exam in aproximately 7 hours

#

.

mossy sandal
#

go study

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dont help me no more

timber gale
#

but im here

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yeah ik lol

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i kinda confused myself aswell

mossy sandal
#

alr ill close it

timber gale
#

aight ciao

mossy sandal
#

.close

vocal sleetBOT
#
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keen lotus
#

how to prove that DA=DB when C,H,D in 1 line

keen lotus
#

triangle ABC has medians BF, AE intersect at H. CH intersects AB at D. Prove DA=DB

vocal sleetBOT
#

@keen lotus Has your question been resolved?

vocal sleetBOT
#
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After 15 minutes, feel free to ping <@&286206848099549185>.
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Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

timber gale
#

umm faf

vocal sleetBOT
timber gale
#

@fluid obsidian sorry to bother you if your not bothered doing it its fine

#

taken channel soz

gilded widget
#

is it the same question

timber gale
#

but howd you get the 4/5

#

yes

gilded widget
#

send it again

timber gale
#

siince im trying to reproduce what he did

gilded widget
#

what was the help number before

gilded widget
#

do you mean the 4/2

fluid obsidian
#

Which 4/5?

timber gale
#

yes

timber gale
gilded widget
#

you wanna take the total amount

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minus the ones that are less

fluid obsidian
gilded widget
#

thanks

timber gale
#

what so if its 40000 its 4

gilded widget
#

?

fluid obsidian
gilded widget
#

its called rabbids

#

rabbids invasion

timber gale
#

yeah

fluid obsidian
#

Ah alright

timber gale
#

so how does one get 4?

fluid obsidian
#

We want a number less than 40000 so the number will start with 3 right

timber gale
#

ah

fluid obsidian
#

And the remaining 4 digits are 4,4,5,6

#

Which can be arranged in how many ways?

timber gale
#

4!

fluid obsidian
#

/2! As two 4s

timber gale
#

yep

#

so if we apply that to this question

gilded widget
#

is the ! necessary

timber gale
#

so it would be 5! - 3!

gilded widget
#

uhh i believe so

#

wait hold on

timber gale
#

5!-3!=114 book said 48

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whats with 48 nowadays

gilded widget
#

wait yeah i think i know

#

uhhh gimme sec let me try to put it in a sentence correctly

#

so total amount of arrangements is confirmed 5!

#

we can confirm that much

timber gale
#

yes

gilded widget
#

if 3, theres 4! arrangements

#

if 4 theres 4! arrrangements

#

if 5 theres 4! arrangements

#

ahh

timber gale
#

nani

gilded widget
#

so basically

timber gale
#

is that a ahh understanding or ahh screaming

gilded widget
#

it would be 5! - 4!*3 i think

timber gale
#

whered *3 come from

gilded widget
#

yep it is

gilded widget
timber gale
#

ah those 3

gilded widget
#

the if statements came from

#

if X is placed at the front

#

then there are 4! arrangements

#

and 3 things fill the spot for X

#

yeah 48 makes sense

gilded widget
timber gale
#

if you dont mind me asking this

#

if its a less than question why are we doing 3,4 and 5

gilded widget
#

we did it the long way i believe

timber gale
#

i swear permutations theres either long way or logic i dont know anymore

gilded widget
#

what i just did was taking the total amount of arrangements

#

and minusing the ones larger than 30000

timber gale
#

yes

gilded widget
#

to get all the ones less than 30000

timber gale
#

I see

#

and then you had the if statements alright let me try and soak these into my brain

gilded widget
#

we could have easily just done

#

2* 4!

#

im so dumb

timber gale
#

well

#

ive done

#

2x4x3x2x1

#

=48

gilded widget
#

yeah thats right

#

thats 2*4!

timber gale
#

ah yep

gilded widget
#

just ignore everything i said before

timber gale
#

but it just doesnt work on duplicates ig

gilded widget
#

uhh

timber gale
#

or i just straight up ignore duplicates at this point

fluid obsidian
#

Which question are you asking?

gilded widget
#

arranged below 30000

fluid obsidian
timber gale
#

we were tryna figure out the way you were doing it and reproduce it

gilded widget
#

lmao thanks

timber gale
#

I feel like ive heard this convo before

fluid obsidian
#

That will be 3×4!

gilded widget
gilded widget
#

less than 30000

#

not more than

fluid obsidian
#

It's 5!-2(4!) or 3(4!)

timber gale
#

48 is the answer tho

gilded widget
#

but thats for more than 30000

#

we want less than 30000

fluid obsidian
#

Oh is it

gilded widget
#

which is just like reciprocated numbers

fluid obsidian
#

Yeah my bad

gilded widget
#

that you said

gilded widget
timber gale
#

yes

gilded widget
#

nice

fluid obsidian
#

It's 5!-3(4!) or 2(4!)

gilded widget
#

yea

timber gale
#

but i have more questions to go through and permutations is really broad so im gonna suffer for a while so...im gonna go suffer now.

#

conclusion permutations just aint it

fluid obsidian
#

Do you know about rabbid invasion?

gilded widget
#

hm

timber gale
#

yes, its a cartoon

fluid obsidian
#

The thing in Meehee pfp is rabbid

timber gale
#

yes?

#

you aussie aswell meehee?

#

.close

vocal sleetBOT
#
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fluid obsidian
vocal sleetBOT
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hearty dragon
#

How do i do this question

vocal sleetBOT
hearty dragon
#

It gave me this

#

Is it right?

timber gale
#

your image or paste didnt work

hearty dragon
timber gale
#

im not gonna lie man, i dont know how to figure that question out but you need to do working out.

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vast shale
vocal sleetBOT
vast shale
#

PGF question

#

i know that the coefficient of the power t is the probability x = that number

#

for example 1/6 t ^2 means that the probability x = 2 is 1/6

#

i answered 0 here since no there is no coefficient of power of 3

#

gave me wrong answer

plain minnow
twin meteorBOT
#

Mikkel

vast shale
#

triple differentiate, plug in 0 all over 3 factorial

#

?

#

i dont understand this

plain minnow
#

Yeah

vast shale
#

it is what it is thank you

#

.close

vocal sleetBOT
#
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ruby relic
#

How many bitstrings of length eight either begin with 00 or end with
101?

vast shale
#

where are you facing difficulty in this problem?

ruby relic
#

how exactly do I find the common numbers

rugged orchid
#

Does either mean or or xor

ruby relic
#

or

vast shale
ruby relic
#

we need to subtract ones with 00 and 101 together due to double counting right

vast shale
#

yep good

#

so you need to remove the count of strings starting with 00 and ending with 101

#

you are facing problem in this?

ruby relic
#

so is it 2^6+2^5-2^3?

vast shale
#

yes

#

correct!

ruby relic
#

no

#

I searched it on internet (to double check) and multiple website have written something else

rugged orchid
#

What numbers in 8 bits start with 00 and end with 101

ruby relic
#

How many bit strings of length eight either begin with 00 or end with 101?
But there are also ⌊20/6⌋ = 3 that are divisible by both 2 and 3, so the total is 10 + 6 − 3 = 13. (c) How many bitstrings of length eight either begin with 00 or end with 101? Solution: There are 26 that begin with 00, 25 that end with 101, and 23 that start with 00 and end with 101.

vast shale
#

ohh I get it

ruby relic
#

hello?

vocal sleetBOT
#

@ruby relic Has your question been resolved?

ruby relic
#

<@&286206848099549185>

vocal sleetBOT
#

@ruby relic Has your question been resolved?

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wintry walrus
#

Looking for help with question 6.e not sure how to solve with a number in front of the squared term

vast shale
#

factor out a 2 from all the terms first

wintry walrus
#

-14 I mean

vast shale
#

not just the d^2 term

#

factor out 2 from every term of the quadratic

#

2(d^2-4d+1)

#

then complete the square of the inside

wintry walrus
vast shale
#

the same way as you did the earlier parts

#

,tex .cts

twin meteorBOT
wintry walrus
vast shale
#

complete the square of d^2-4d+1

wintry walrus
vast shale
#

how did you do part a?

wintry walrus
#

I just haft the 2 x and x ^2

vast shale
#

do the same thing with x^2-4x+1

wintry walrus
#

(d-2)^2 - 3

vast shale
#

yeah

#

d^2-4d+1 = (d-2)^2 - 3

#

now multiply everything by 2 to get the final answer

wintry walrus
outer warren
#

not like that

#

exponentiation takes priority over multiplication

#

you just leave that term as
$2(d-2)^2$

twin meteorBOT
#

ℝamonov

wintry walrus
#

And is that the answer ?

outer warren
#

no

#

you didn't read what I said

#

now the factor of two has disappeared from the first term

wintry walrus
#

That was an accident

vocal sleetBOT
#

@wintry walrus Has your question been resolved?

#
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fast quarry
vocal sleetBOT
fast quarry
#

I dont understand how w^-1 = x

sage burrow
#

are you comfortable with everything on this table

#

i.e what i presume you have already deduced

fast quarry
#

yeah yeah

sage burrow
#

definition of inverse:
an element a has an inverse 'a^-1' such that

a * a^-1 = e, a^-1 * a = e

fast quarry
#

its just the w^-1 = x is not making sence to me

sage burrow
#

here we have a=w

fast quarry
#

OH

sage burrow
#

what element 'w^-1' of the elements (s,t,u,v,w,x,y,z) satisfies this

#

your latin square should tell you

#

(note e=s, here)

fast quarry
sage burrow
#

no worries lol

#

hope it makes sense now

fast quarry
#

thanks yeah

#

.close

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glass galleon
vocal sleetBOT
glass galleon
#

am i right wit A here?

#

<@&286206848099549185>

vocal sleetBOT
#

@glass galleon Has your question been resolved?

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outer kite
#

The following initial value problem has to be solved
I have no idea how to solve that, can somebody please help 🙂

outer kite
#

$x^{'}(t) = ln(t)*e^{-x(t)}, x = x(t), x(1) = 2$

twin meteorBOT
flat whale
#

,w solve dx/dt = log(t) e^(-x)

flat whale
#

probably try separation of variables

outer kite
vast shale
#

ks

outer kite
#

.close

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#
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graceful fox
#

$$\forall n \in \mathbb{N}^*, \int{0}^{1} \frac{x^n}{1 + x^n} dx = \frac{\ln(2)}{n} - \frac{1}{n} \int{0}^{1} \ln(1 + x^n) dx$$

twin meteorBOT
#

koji1001

graceful fox
#

how to show this

orchid yarrow
#

integ by parts*

graceful fox
#

I tried

orchid yarrow
#

Let's try to make (x^n-1)x in numerator

#

does that clicks something?

graceful fox
#

owww

#

i think i got it

#

let me write it

#

yea did it

#

thank you

orchid yarrow
#

No worries

graceful fox
#

.close

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hearty dragon
#

How do you do 12

vocal sleetBOT
hearty dragon
#

I know its permutation

#

But when i did it it gave me a huge number

#

So im not sure if i messed up or not

wraith venture
#

Should you count the permutations ?

hearty dragon
#

I did

#

For permutations you divide the toal amount over the amount you need

#

So for number 12 it would be 17/10

#

Then you would do a formula

wraith venture
hearty dragon
wraith venture
#

Is every permutation alphabetically ordered ?

hearty dragon
wraith venture
#

Is it though ?

hearty dragon
wraith venture
#

"they must be arranged alphabetically"

hearty dragon
#

Since they have to be arranged alphabetically

wraith venture
#

But you shouldn't

#

Because you should not be allowing every permutation

#

You should only be allowing one

#

The alphabetically ordered one

hearty dragon
#

Were organizing books

wraith venture
#

Yes

#

Once you picked 10 books, there's only 1 way of arranging them

hearty dragon
#

But what if were choosing 10 different books each time

#

So that would create more combinations

wraith venture
#

But still only 1 permutation per 10 books

#

So it's 17C10

hearty dragon
#

Wouldnt it be 17p10

#

Since the order you do it is important

wraith venture
#

What does 17P10 represent

wraith venture
hearty dragon
#

oh now i get it

#

I have to find the combinations of which 10 books im choosing

vocal sleetBOT
#

@hearty dragon Has your question been resolved?

#
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dry rover
#

suppose h(z) = f(z) + g(z)

if |f(z)| is always greater than |g(z)| for all z in a simple closed contour, in which h,f,g are holomorphic.

since |f(z)| > |g(z)| >= 0 for all z in the interior of the contour

so |f(z)| must always be larger than 0?

then |h(z)| will always be bigger than 0 in the interior of the contour?

So, there are no 0s? at all?

i suppose if there is a case where |f(z)| is larger than |g(z)| in some annulus, and |g(z)| is larger than |f(z)| in the smaller circle (that together with the annulus, makes up the region h(z) is being considered in, then there might be 0s then?

but in case 1? h(z) is never 0?

flat whale
#

so |f(z)| must always be larger than 0?
this is true regardless of g(z)

#

then h(z) will always be bigger than 0 in the interior of the contour?
did you mean |h(z)| here?

dry rover
#

yes

#

thank you for pointing that out, edited

dry rover
#

wait, doesn't need to be a circle

vocal sleetBOT
#

@dry rover Has your question been resolved?

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#

@dry rover Has your question been resolved?

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lofty spindle
#

I do not get question 6 (vectors)

vocal sleetBOT
lofty spindle
#

can't seem to solve it graphically (cant construct it)

brittle lion
#

you can assume the direction of one vector first

#

suppose a is facing to the positive-x direction

lofty spindle
#

I understand that but how do I connect that vector addition indicated

brittle lion
brittle lion
# lofty spindle

when you add two vectors, let's say a and b, you put the 'tail' of vector b on the 'tip' of vector a

lofty spindle
#

I understand but is mine considered incorrect

#

Mine is following that rule though

#

The tail of vector b starts like what you have did

#

But the letters are switched

brittle lion
brittle lion
lofty spindle
#

good point

#

but how do i graph the vector addition?

brittle lion
#

there's two method you can use, wait let me draw it

lofty spindle
#

tq

#

im going to draw the parallelogram

#

did i do it right?

brittle lion
#

in your diagram, the vector b and c is swapped

lofty spindle
#

im confused

#

why must the letters be in that specific way

#

because the vectors are still from tail to head relative to A

#

but the letters are just swapped

brittle lion
lofty spindle
#

is there a rule that im unaware of?

brittle lion
#

the angle between a and b should be 45°, not 90°

lofty spindle
#

you're right

#

let me fix that

brittle lion
#

alright

lofty spindle
#

@brittle lion

#

i got to here so far

#

is this the vector that im trying to find?

brittle lion
#

yes!

lofty spindle
#

perfect

brittle lion
#

keep in mind that since they are unit vectors, the length are all 1

lofty spindle
#

got it

#

question

#

which angle do i have to use

#

i am confused about that

#

is it the angle between -2b and 3c?

brittle lion
#

My interpretation to the problem is that you are told to calculate the magnitude analytically and then use the diagram to verify

#

so..

#

do you know how to break down a vector into it's x and y components?

lofty spindle
#

no

#

i didnt learn that from my teacher

brittle lion
#

oh okay let's find a different way

lofty spindle
#

in fact we were never shown how to do these type of questions

brittle lion
#

oh shoot

lofty spindle
#

i can show you the question we did in class

brittle lion
#

don't worry I'll help you

lofty spindle
#

this is the question that we did in class today

#

thanks man

#

what i meant to say is that we never learned how to do it with 3 vectors

brittle lion
#

okay i think we'll use cosine rule

lofty spindle
#

kk

brittle lion
#

yeah

lofty spindle
#

oh

#

wait

#

angle between -2b and 3c would just be 45 degrees

brittle lion
#

yeah that's correct

lofty spindle
#

ok that's easy then

#

just use sin rule

brittle lion
#

okay

#

I'm gonna use my laptop

#

I'll show you another method to solve it

lofty spindle
#

kk

#

thanks

#

something's not adding up

#

the answer is supposed to be 1.64

brittle lion
#

okay let's see

#

oh i know

brittle lion
lofty spindle
#

for the addition vector?

brittle lion
#

yes

lofty spindle
#

ok

brittle lion
#

like this

lofty spindle
#

give me 5 m

#

ill redraw it

brittle lion
#

alright

#

I think we should calculate a - 2b first

lofty spindle
#

would just be 2 no?

#

for magnitude

brittle lion
#

I'm not sure though

lofty spindle
#

hm

#

im just going to move on to another question

#

im wasting too much time on this question

brittle lion
#

alright sorry for not being able to give much help

lofty spindle
#

ay man

#

thanks for trying

vocal sleetBOT
#

@lofty spindle Has your question been resolved?

lofty spindle
#

close

#

no idea how to close it

#

ill just wait till it time outs

vocal sleetBOT
#

@lofty spindle Has your question been resolved?

#
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vast shale
#

Hey

vocal sleetBOT
vast shale
#

Find the equation of the trigonometric graph

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#

@vast shale Has your question been resolved?

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craggy helm
#

How does it know the interval?

vocal sleetBOT
craggy helm
#

does it assume it's between 0 and 1 because it wasn't given or what? I'm confused

vocal sleetBOT
#

@craggy helm Has your question been resolved?

flat whale
craggy helm
#

oh so it's the site

#

ok gotcha

#

.close

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craggy helm
#

Can somebody explain me this?

vocal sleetBOT
craggy helm
#

I'm confused.

thin vale
#

2y^2 is y^2+y^2 right?

#

so you have y^2+y^2=y^2+4

#

subtract y^2 from both sides of this equation

#

and you get y^2=4

craggy helm
#

omh

#

I'm seriously losing my mind over the simplest things

#

Sorry! Such a dumb question! Thank you!

#

.close

vocal sleetBOT
#
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dry rover
#

so erm, just to continue from earlier, since my question wasn't fully answered

#

for rouche's theorem, given h(z) = f(z) + g(z)

where |f(z)| > |g(z)| for all z in the interior of some closed contour

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so minimum of |g(z)| is 0, and thus, |f(z)| must be greater than |g(z)| >= 0

then, |h(z)| will always be greater than 0 then?

so h(z) does not have any zeros?

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for all z in the interior of said contour.

h,f,g are holomorphic in the interior of the contour

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it sounds simple, but i am trying to understand rouche's theorem in a concrete way, starting with "simple" examples.

vocal sleetBOT
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dry rover
#

for rouche's theorem, given h(z) = f(z) + g(z)
where |f(z)| > |g(z)| for all z in the interior of some closed contour

so minimum of |g(z)| is 0, and thus, |f(z)| must be greater than |g(z)| >= 0

then, |h(z)| will always be greater than 0 then?
so h(z) does not have any zeros? since it has the same number of 0s as f(z) which is never 0

vocal sleetBOT
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vocal sleetBOT
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dry rover
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.reopen

vocal sleetBOT
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vocal sleetBOT
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vocal sleetBOT
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vocal sleetBOT
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hidden badger
vocal sleetBOT
hidden badger
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how do i do (b)

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i dont know what i did wrong

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.close

vocal sleetBOT
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vocal sleetBOT
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prisma viper
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can anyone help me with b

vocal sleetBOT
#
What step are you on?
1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
prisma viper
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2

strange crater
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show what you started doing

potent anvil
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think about whether A affects the probability of R

prisma viper
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yh, it does

potent anvil
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so if two events affect each other, are they dependent or independent

vocal sleetBOT
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@prisma viper Has your question been resolved?

prisma viper
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independant

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oh no, dependant

vocal sleetBOT
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@prisma viper Has your question been resolved?

heavy yoke
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so if you choose box one does that change the probability of a red ball getting drawn?