#help-39
1 messages · Page 169 of 1
Edmund Cloudsley
now what since addition is associative i.e. (a + b) + c = (a + c) + b
we can say that
$$ = (a^2 + 2ab + b^2) - b^2$$
Edmund Cloudsley
now I am sure this reminds of the familiar identity of (a + b)^2
therefore we can write this equation as
$$ = (a + b)^2 - b^2$$
Edmund Cloudsley
this is known as the "completing the square" method
and it is quite commonly used for factoring equations
the 2ab is part of the expansion of (a + b)^2 now
we know that
$$(a + b)^2 = a^2 + b^2 + 2ab$$
Edmund Cloudsley
this is just the opposite of this identity
of you'd like to know why
$$(a + b)^2 = (a + b)(a + b) = a^2 + ab + ab + b^2 = a^2 + b^2 + 2ab$$
Edmund Cloudsley
or you can also use binomial theorem to expand this one
but that's bit of an overkill
$$(a + b)^2 = {}^2 C_0 a^2 b^0 + {}^2 C_1 a^1 b^1 + {}^2 C_2 a^0 b^2$$
Edmund Cloudsley
Alright. 1 minute.
take ya time
After completing the square, what does the fourth part mean?
the 4th and 3rd part are both completing the square
in the third part, we are setting up our equation to apply completing the square method
in the fourth part, we are actually applying the completing the square method
in your case, $a = 2x^2$ and $b = 3m^2$
Edmund Cloudsley
Oh the drawing method. I want to know how the third part looks like based in (a+b)²=a²+b²+2ab
Something like that.
oh I understand what you are trying to say
You want me to illustrate how the third part fits in the idea of completing the square method
Yes
I made a draft in here.
$$2(4x^4 - 13x^2m^2 + 9m^4)$$
let us write $2x^2$ as $a$ amd $3m^2$ as $b$
$$$$
Then this equation would be
$$2[(2x^2)^2 - 13x^2m^2 + (3m^2)^2]$$
$$2[a^2 - 13x^2 m^2 + b^2]$$
let us subtract and add $+2ab$ and $-2ab$ so that we can set this up for completing the square method
$$2[a^2 -13x^2m^2 +b^2 + 2ab - 2ab]$$
$$2[(a^2 + 2ab + b^2) - 13x^2m^2 - 2ab]$$
$$2[(a+ b)^2 - 13x^2m^2 - 2ab]$$
now we can resubstitute $a$ and $b$
$$2[(2x^2 + 3m^2)^2 - 13x^2m^2 - 2(2x^2)(3m^2)]$$
$$2[(2x^2 + 3m^2)^2 - 25x^2m^2]$$
Edmund Cloudsley
Alright,give me few minutes.
take your time
I would have to take my leave now unfortunately
I shall let someone else continue
Okay, when I have a problem I will ping you by then.
@wild temple Has your question been resolved?
Not yet, I'm analyzing on my copy.
@midnight haven I'm bad at explaining. I am stuck again.
Does factorization have cancellation?
@wild temple Has your question been resolved?
@midnight haven can you explain me on note book I want to understand visually and orally at the same time ; it's like taking a lecture in class.
My explanation,I feel like I explained everything wrong.
Can you make some corrections. I was explaining my best but my understanding is less and not complete.
It is complete ma man
I think you did it quite well
You took some time but you got there
Hold on.
Unfortunately I would be unable to do that since that would involve me revealing my voice on this server.
Something I am not comfortable with
I explained till there.
alrighty
The last 3 steps can you tell me how?
for the parts after that, we have to use a different identity
in particular
this one
$$a^2 - b^2 = (a + b) (a - b)$$
Edmund Cloudsley
in your case if you take $a$ as $2x^2 + 3m^2$ and take $b$ as $5xm$
you should be able to solve it
Edmund Cloudsley
its all about recognising the corrrect identities
You may wish to review those before you proceed
You may use this link to brush up on those if you'd like
5² = 25 so with x² and m² it will be (mx)²?
Edmund Cloudsley
The last step though, how to understand it?
It’s an application of this identity
I don't understand because the last step has 4 operators (two "+") and (one "-" one "+")
This = to one plus and one minus.
@midnight haven
Can we take this through dms.
I don’t quite understand ur question
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im doing a practice paper right now for studying and using a textbook to help me, but i can't figure this out, the equation above is x^3 + 4x^2 - 13 = 0
AnshumanNeon
AnshumanNeon
then square root both sides
if it helps u understand u can put bracket around 13-x^3/4
helped me when i started these types of questions
$$x = \sqrt{\frac{13-x^3}{4}}$$
AnshumanNeon
and there you go
thank you
yeah it helps
to make it clear, i used latex
i don't use latex, but it helps me practice it
🙂 glad it does, im studying for my finals rnnnn 😭
never used that sounds nice
haha
this is latex
but it converts to this then
good luck
tysmmm u too
convergence
another thing im confused about is iterations? there's a follow up question asking about it but i literally can't figure it out even using my textbook
ah yes!
what's the question. i didn't get what you meant by iterations
iteration formula basically means to repeat the formula again and again @simple gyro
okay thanks
my suggestion would be to find x_3 in this case
i haven't seen a question like that tbh
it is very commonly used in convergent sequences
i haven't seen much so ig its just that i live under a rock
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what would be the first step to do this question?
Personally, I would make a substitution, u = x - 1
is the answer 2/pi?
Idk
rewrite it as tan(pi x /2)/(1/(1-x)) then use l'hopital
I didn't solve
shouldn't it be one?
this makes sense and makes things a little easier but, is there a specific rule as to where to apply the substitution?
yeah I got it
Yep right
okay, thank you
Anytime!
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last quastion
Calcus 1
a 2 / b 2 / c -3 / d 2 , my answers
uh so for a. u get that lim x->2- f(x) = 2 ?
no I got -2
missclick
sorry but last one isI didn't find the solution
and for b
2
how did u get 2 ?
It’s a bit hard to explain since English is not my first language, but when I went above 4, I reached the two closest functions
what is ur language ?
There is no function when going down, and I went up and reached the result of 2
turksh
ah i dont speak turkish
"Could you explain how you found your solution if mine is incorrect?
Oh, right, my mistake. I thought it was the beginning of the blue line
mb
I thing C is correct
no
u found -3 ?
yes because goes to -3
when x= 0 - ?
-3 is not even on the graph
Can I do my solutions through print and share them again with you as long as the chat stays open
yes
i didnt rly understood what you meant but ok
Its looks like this
I did go left from the 0 and then I saw the blue line and its going to -3
x is on the horizontal line
u go at x=0-
and you watch above or under the point where you are
under
not really
it is exactly wher u are
I go litelbit left because its -
and then going to down side
for example, here, x was blocked at 4 since u look for the limit when x=4
so u watched above and under you until you meet the graph
and in this case, you meet the graph at y=4
yes I did and then up side I didnt find something
I went down side
u dont have to move here because it is 0
for the question before yes
when x tend to 4
I think I got it so I followed this solve style and then I looking for quastion D
answer is it 5?
or my old answer -3
none
can u draw how you get those answers please ?
sure
i can't understand how you think
for D
yes it is 2
how could u find 5 ?
i dont know my answer was 2
for 5 I try to go last part
but It was bad idea
okey I got it 2 quastion can we look for last one?
for e ?
yes
can you share the soliton with me?
I have no idea
it is undefined since the limits when x>0 and when x<0 are not the same
so what should write to answer gap
D.N.E ?
undefined is good i think
ok thank you for answering my all quastion sir
where do you live btw?
u said maybe I can try to speak ur own language so thats mean u are not from UK
lol
im french
ohh cool I am tryin to develop my english sorry for that
sorry for what ?
I passed my depertman with C1 certifation but still not enogh
my english bad
You needed to put in more effort
sorry about that
its ok bc i was doing the same mistakes before, so i can still unnderstand
uh me ?
yes
wait I write wrong I guess
I mean u tryed to hard because my english was bad
ah ok i just understood
thanx again
good luck
understandable enough
thx
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Hey can someone just tell me why this is wrong?
I'm guessing third line went wrong, but if that 1st term had 2 terms it would be fine I'm guessing. I think it's due to lack of conceptual knowledge of how factorization gives you roots
just b/c two things multiply to 36 doesn't mean that one of the factors is 36
ex. 4 and 9, 6 and 6, 3 and 12, 8 - 2 sqrt 7 and 8 + 2 sqrt 7, etc.
If it was like (a-1) instead of a in the first term, would it be fine?
just b/c two things multiply to 36 doesn't mean that one of the factors is 36
Why does this work then?
zero is special
It's the only number c for which you can say ab = c -> a = c or b = c without anything else
As a proof, suppose that a and b aren't zero
then ab clearly isn't zero, a contradiction
hence at least one of a and b is zero

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How we get logb(x)=ln(x)/ln(b)
see the steps for number four
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When doing subspace iteration using QR decomposition, my algorithm is convering too fast due to a bad stop condition. Although this stopping condition is mandatory for this assignment:
while(1)
P = matrix * Q;
[mQ, mR]= SN_gs(P); % QR decomp
if(
norm((eye(rows, rows) - (mQ*mQ')) * Q)
<= tol
)
mQ = Q;
disp(runs);
break;
end
Q = mQ;
runs = runs + 1;
end
Stopping condition is
norm((eye(rows, rows) - (mQ*mQ')) * Q)
As defined in my assignment:
Tolerance level is 10^-6...
I see that mQ * mQ' gives almost a unity matrix... so maybe rounding errors
@sage cobalt Has your question been resolved?
Is your answer bad? There is nothing wrong with it converging too fast
@sage cobalt Has your question been resolved?
My eigenvalues are just off
but my algorithm is just not working properly... sometimes it does not converge and keeps between 0.7 and 0.2... Im so fcked
You haven't really provided enough information to say anything, it sounds like this has nothing to do with your stopping condition because your assignment is unlikely intended for you to turn into a long-winded exercise in arithmetic precision and regularization techniques outside the scope of your class
Some matrices work, some don't. I have no clue what is happening...
This is my algorithm:
while(1)
P = matrix * Q;
[mQ, mR]= SN_gs(P);
disp(norm(Q - mQ));
if(norm(Q - mQ) < tol)
mQ = Q;
break;
end
Q = mQ;
runs = runs + 1;
end
It is subspace iteration using QR decomposition
Well, it seems like it is... The implementation of subspace iteration is supposedly the exercise, but debugging it to work with the random matrix generator is the most difficult part ):
I have this matrix for example: (condition = 10)
This will not converge under any stopping condition I use.
This matrix works fine: (condition > 10^4)
Is it supposed to converge for your first example?
Yes it should, but what it does is run only once. The stopping condition is already < 10^-10. But this algorithm is supposed to find eigenvectors, and it is concerning that it just stops without making any progress...
I don't know this algorithm, and I'm not looking at your work very hard, but it looks like the magnitude of your eigenvalues are the same there and I don't know how your algorithm is expected to converge on a local solution there
What happens if you take your first example and add a random diagonal matrix with very small values like between +-0.02
okay well that's a regularization technique, and the first thing I said was that I didnt expect your class to need you to go off on some regularization tangent
so I don't know what your are expected to know
Interesting, the matrices that we use are generated using a provided matlab function...
the idea is that if your eigenvalues are poorly behaved, by the greshgorin circle theorem, if you perturb your diagonal by a very small amount, the probability of the new matrix being poorly behaved is on a set of measure zero and it can fix your problem by introducing a small error
For smaller matrices this technique works, but once the size of the matrix rises, the iterations fall to 1 again
in your case, since it is randomly generated, the probability of a 2x2 matrix having complex eigenvalues and thus problematic is very high
so I guess in some sense you also got lucky
Like I said, I don't really know what you are doing. This looks like some sort of power method, but this isn't really something I use
So it is possible that my other matrices also have complex eigenvalues which is causing problems, correct?
Or not?
My assumption is that if your matrix just happens to have two largest eigenvalues in magnitude
then your algorithm probably can't converge
so by perturbing your matrix a little bit in that case, you will move your eigenvalues around a little bit and hopefully you won't have your largest eigenvalues be the same in magnitude anymore
The problem is that in the 2x2 case, if you have a-bi and a+bi as eigenvalues
then |a-bi| = |a+bi|
so there is a chance that what is happening is that your algorithm is going towards the eigenvector corresponding to one eigenvalue, but then gets stuck trying to travel to the other eigenvector and gets caught in a loop
This is very complex mathematics
You should worry about making sure your algorithm works when there is 1 largest eigenvalue
and just ask your instructor about the edgecases
There is a reason why nobody actually implements their own numerical linear algebra routines, they are finnicky and filled with edge cases
You have a lot of knowledge
Thanks a lot for taking your time to share, I really appreciate it. I will read again and use your insight
Thank you
good luck
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Where can I see the finding of all solutions x^2-y^3=17?
(x,y integers)
I mean you could always graph it
It's endless, and as far as I know there are only 8 solutions here
<@&286206848099549185>
set y to 0 and x to 0 and solve for both intercepts?
?
x and y are different numbers
I think that’s not all solutions
to find the x intercepts
x^2-0=17
x^2=17
x intercepts at plus minus sqrt(17)
for y intercept
0-y^3=17
y=cube root(-17)
y intercept at negative cube root of 17
Yep
.
This question has actually got me thinking, what grade maths is this (or uni)
interception for x values at
(-sqrt(17),0) (sqrt(17),0)
interception for y value at
(0, -cuberoot(17))
(282; 43) solution
wdym
U can check))
we can see your graph extends to positive and negative infinity which means the domain of X accepts all real numbers
whered u get that solution
I saw on the graph
I know these are the answers but no idea how they found them
where'd u get that
Wolfram or smth
Yea wolfram
Look at integer solutions
with calculator
this is, ofc, not easy to prove
Do u know how?
I understand it
http://magma.maths.usyd.edu.au/calc/
Enter: E:=EllipticCurve([0,0,0,0,17]); IntegralPoints(E);
this specific problem is mentioned in various literature:
Do you have a solution without computer search?
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jst need someone to explain this step to me
should be a very quick question
$x^2 - 6x + 10 = \blue{x^2 - 6x + 9} + 1 = \blue{(x-3)^2} + 1$
Лайка
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#help-39 message i thought having solving couple of this question i finally understand how to do this kinda question. But apparently not...i used the same method but somehow i got it wrong again and idk where i made mistake...
(excuse of messy handwritting)
also here is the answer
could anyone be kind enough to work me through how to get that answer or point out what i made mistake in my work
Check blue again
More specifically, what the bearing is relative to ( west of south )
@somber heron Has your question been resolved?
ok, i checked again. But i still dont understand what i did wrong here...like it says 10 degrees west of south so doesnt that mean its like 10 degnvm as i was typing i noticed i was using the wrong side of the angle
i did the calc again with the correct bearing, it did match up the answer.
but wait why is the direction W of N
the question asks what direction should they be walking to
What do you mean
.
Im assuming origin(0,0) is their home, after the last vector(green) arent they supposed to walk toward E of S direction and go back to origin
?
i do get the path that toward to their home(purple), in terms of vector, it should be pointing N of W, but the question is confusing to me.
^
I just re-read the question and yeah you are right. The answer should be 3deg S of E or 87deg E of S I believe
@somber heron
Ah no nevermind, this confused me because of your diagram
The tip of the green vector should be in quadrant 4. Which means the direction back to the origin will in fact be up and left
Yeah, the angles are too steep and the lengths all look equal
yeah
looks something like that
it now makes sense
Thank you so much for answering my question!
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Five cards are drawn from a standard deck of cards. What is the probability of being dealt one pair?
Can someone explain why this is the answer:
(52x48x44x40x30)/52P5
where does 30 come from?
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@simple elbow Has your question been resolved?
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if anybody here is familiar with the hp prime GDC, can somebody explain why i cant put this equation into the functions app to plot it?
this is the equation im trying to solve and i was trying to do it graphically by putting the line equations separately and finding where they intersect
@wraith badger Has your question been resolved?
what the freakity doodles
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can't figure this one out
just need some clarification
when it becomes ln(10x)^3
is that valid
im tired asf and i'm forgetting my log rules
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yes
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i know the formula but not sure how the formula works
the formula would be 15-4+1c4
@rich jolt Has your question been resolved?
(15−4+1) is how many gaps there is around 11 days
like if you need to choose 2 days out of 6
.D.D.D.D.
you put 2 days anywhere in the 5 gaps around 4
(6−2+1)c2
you can also do it differently, with stars and bars
@rich jolt Has your question been resolved?
but why does choose it causes gaps
that's the condition
they can't be consecutive
meaning they can't touch
one chosen day fits in each gap, 0 is fine, two is not allowed
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Can someone check it for me
This needs a lot of words.
Even if the calculations are right, I'd grade this at like 75% at most
fuck allat
What should i write on it
what's ur fav dinosaur
What am i missing.
Hast du Induktion vesucht?
Why are you writing this? How do you know it's true?
Isn't that what you're trying to prove?
base case of induction, written poorly that it works for some k in N
I just read some article on internet and we assume its true when when its n
I know why khishi is writing it, but it needs to be written that you're assuming that part for the sake of induction
well as said, written poorly 
And use this to prove n+1
Yeahh im in subway and forgot my pen. So didnt want to write more stuffs.
der will sagen, du solltest noch hinschreiben, dass die Aussage wahr ist für mindestens ein k aus N
und dass du das benutzen wirst im Induktionsschritt
entweder in worten oder mit logik
ja eig schon
Es existiert ein n aus N so, dass f(n) wahr ist
achso ja kannst n benutzen
Formal gesehen, würde man am Ende noch einen Schlussatz schreiben
Nach dem Prinzip der v.I. ist f(n) für alle n aus N wahr.
Es ist halt ein Beweis den du da machst
es ist nicht nur bloß umrechnen und umformen
Verstanden.
und dagehören halt langweilige, repetitive aber wichtige Formalitäten
Okay. Danke.
no problem
Ich habe andere Probleme
mentale?
du ich war zwar gut in stochastik, aber ich hab keine ahnung
kanns es aber sein, dass da was fehlt
Einen Moment
I dont understand the sentence. Define suitable probablility space…
Muss ich alles schreiben die in wahrscheinlichkeitsraum sind?
Also ein WK-Raum besteht aus einer Grundmenge Q, einer sigma Algebra und einem WK-Maß P
Also P ist sowas wie eine Abbildung
Sie ordnet Elementen (Ereignissen) aus der Sigma Algebra (eine Menge aus Teilmengen von Q, da sind halt verschiedene Ereignisse drinnen) und da ordnet die Abbildung P einem Ereignis eine Wahrscheinlichkeit zu
Nichts verstanden.
Danke.
Was macht sigma algebra?
Ok ein Bsp
Q = {1,2,3} dan wäre eine mögliche sigma Algebra Sigma = { {}, {1}, {2}, {1,2}, ... }
Man sieht ja, es ist eine Menge von Teilmengen von Q
{1} ist eine Teilmenge von Q
{2} und {1,2} auch
Hier muss auch Q selbst sein oder?
Ja
P(omega) ist die großte Sigma algebra.
Ja, das war die Potenzmenge wenn ich mich entsinne
Jetzt bin ich nur bisschen verloren, also in der letzten Aufgabe, da war X ja die Differenz der Zahlen, die man gewürfelt hat mit Würfel 1 und 2
Sie ordnet allen Element aus P(A) eine Wahrscheinlichkeit zu
also allen Elementen aus der sigma Algrebra
Also eine Abbildung P : Sigma -> [0,1]
Lass uns zuerst 2.a machen. Danke.
Ist X -5 bis 5?
Man würfelt die Würfel gleichzeitig nehme ich an
Aber es ist geschreiben, dass sie nacheinander gewürfelt sind
ah ok
Jetzt zurück zu 3
M wäre hier doch die Sigma Algebra
Weil man aus Q = {1,2,3,4,5,6} alle möglichen Ereignissen bildet denke ich
wobei ich denke M = Q x Q das kartesische Produkt
man hat ja Zahlenpaare z.B. (6,1) wo man dann eben die Differenz bildet 6-1
usw
X variiert zwischen -5 und 5
Ok
(3,2) und (2,1) beiden resultieren 3-2=2-1=1
Okay
wobei lass mich nochmal nachdenken
Okay.
Ich denke es würde mehr Sinn machen wenn Q = [1,6] x [1,6]
Q ist ja die Ergebnismenge, also die Menge aller möglichen Ergebnisse
ok ich bin lost, ja
Ich bin auch
M = [1,6] x [1,6]
es gibt kein Q in 2)
das wäre dann die a)
b) wäre jetzt einfach Teilmengen von M bilden, die alle das Resultat liefern
2i) wären alle geordneten Paare aus M, die eine negative Differenz liefern, z.B. (1,2) weil 1-2 = -1
Jetzt zurück zu 3 bitte
Ah ok jetzt verstehe ich, M, A, ... , D sind diese Teilmengen
Ist omega=M ?
was genau meinst du mit Sigma
Nicht sigma meine ich omega
𝔸dωn𝓲²s
Ok ja hätte ich auch gesagt
das meinte ich vorher mit Q lol meinter aber Omega
Omega = M
ja würde ich sagen
Das wäre denke ich jetzt die Menge aller Teilmengen von Omega
P(Omega) = { {(1,1)}, ... {(6,6)}, {(1,1), (1,1)}, ... , {(6,6), (6,6)}, ...}
auch wenn {(1,1), (1,1)}, ... , {(6,6), (6,6)} eig keinen Sinn machen, weil das nie passieren kann
Ach so.
man könnte den ja die Wahrscheinlickeit 0 zu ordnen
Was warum?
weil diese Ergebnisse nie auftreten können
Man hat ja ein Paare
man würfelt einmal zwei Würfel
Ach so
{(6,6), (6,6)} wäre z.B. eine Möglichkeit von 6, dass man zweimal hintereinander X = 0 bekommt
aber das ist ja nirgends hier gegeben, was das wirklich bedeutet
wobei man könnte auch simpel sagen P(Omega) = {A,B,C,D,E,M, ...}
Ach so.
ich hab noch ... gemacht, weil es heißt ja alle möglichen Teilmengen deswegen könnte es ja noch weitere kombinationen geben
Jetzt suchen wir alle Wahrscheinlichkeiten
P({X in A}) = ?
...
P({X in M}) = ?
So wie es steht, ist wird das Bildmaß eines Wahrscheinlichkeitsmaß, als Wahrscheinlichkeitsverteilung bezeichnet, aber ich hab wenig Ahnung, ich hatte kein Maßtheorie wirklich
Also anscheindend ist das WK-Maß, die Abbildung, die den Ereignissen die WK zuordnet
und die WK-verteilung beschreibt eher wie die Wahrscheinlichkeiten zugeordnet werden
🍒 : 
Tur mir leid. Ich war ein bisschen beschäftigt.
Mentale Pausen sind okay.
Danke, dass du mir Erlaubnis gegeben hast
hahahah
Okay jetzt wie definiert man es
Das WK-Maß zu finden, ist denke ich einfach
P({X in A}) = ?
...
P({X in M}) = ?
zu bestimmen
Wie würde ich es machen...
Ich würde sagen
Ist es 0 ?
Ich auch, was meinst du A ohne M
|A| ist keine Menge :)
das ist die Mächtigkeit/Kardinalität von A
also die Anzahl an Elementen
demnach ist / nicht ohne sonder bedeutet geteilt
Ach sooo
|A| geteilt |M|
vergeben und vergessen
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Find the number of diagonals in the convex polygon of n sides
I know how to solve this problem but I want to work on a specific approach
Can I use Combinations to solve this problem
Yes you can
How can I approach this problem by using combinations?
Let's think of a 8 sided polygon
Ok
Can you draw and send it?
A diagonal can be created with two vertices and Those vertices can't be adjacent
Let's select the A point
Yeah
How many points are there which I can choose now to form a diagnol?
Write that algebraically
Diagonals from A (everything joining A and Other points except B and H )
Diagonals from B
(everything joining A and Other points except C and A )
And so on
8
Points
Therefore total lines 8*5
n(n-3(
Is this correct?
yes
n(n-3) for the general one and because of the principle of double counting it is n(n-3)/2
Yep
Not n-1
Oh sorry that is a typo
But can I use nCr to find this
Like there are n number of points and 3 points shouldn't be considered if I'm taking a points
You can
what are the total number of lines that can be formed from n nonlinear points?
nC2
Why?
No actually
I still don't understand
Gimme a min
I know this thing
But how is it related
Maybe I don't know the meaning of n-gon
In this we will have total 8c2 lines
Yes
Yes but why do I even get this , can you explain geometrically
Now what we did here was
Yep
Yes
Oh you're subtracting the Line made by the sides , and the line made by the adjacent sides
Ohhh
I guess
Line made by sides are =8
Yup
Oh yeah
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in n sided polygon, n lines would be there which will be the sides of the polygon, they can never contribute to the diagonal that's why you have substracted it
Thanks
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Yes exactly
I wasn't able to put this into words lol
No problem thanks anyways
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Just need some help with intuition, i think there are some rigorous definitinos in topology but for non-pathological examples, is the boundary of a surface basically the edges?
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question. if 6 people are playing russian roulette probability of anyone getting shot is 1/6?
or will we do (5/6)*(1/6) for 2nd person and so on
like multiplying probability of previous people not getting shot
,w binomial distribution
either is happens or it doesnt it depends on the number of events
in your case n=6
p=1/6
q=5/6 where 1 = 1-p
sorry i dont understand what number of events has to do with this
if you had 4 people the chance of someone getting shot would be different
because no one might get shot
i mean there are 6 people and 6 positions for the bullet to be in then what would be the chance of each person losing
because then one of them must get shot
i thought it would be safest to go first but according to my calculations im getting 6th place has best chance of not getting shot
oh so you want to see how the order affects the probabilty
yes
well 6th would be the least safe
because lets say i am player number 1
theres a 1/6 chance
if i dont get shot player number two had a 1/5 chance
3 => 1/4
nono i mean
6 => 1
by that logic probability of 6th person getting shot becomes 1
but
thats not my question
i mean lets say 6 people are playing
what would be the best order out of 6 to go
like would the 1st person have most chance of getting shot or 6th
I'd be the same I'm certain
because what is the inherent different between person place number 1 and place number 6
yes that was what i asked initially. like would it just be same or do we multiply it with probability of the previous people not getting shot
and if not then why
well lets say for person 2 the probabilty that they get shot is the p(player 1 survives) and p(bullet in the right chamber)
$p(p 1 lives) = 5/6$ ; $p(p 2 dies) = 1/5$
Nyxzore
p(event) which is player 2 dying is p(a) *p(b)
that is 5/6 times 1/5 which is --> 1/6
try that same logic for the third person
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How I find M^-1
Right I used that
that one of the matrix is a rotation
make it into one first
But like in the mark scheme it’s separated
i see
yes
simpilfy (AB)(B^-1A^-1)
Why u multiply by AB again?
I’m talking about ultrafilter
):
AB is just M
just do it and u'll see why
yes M = AB
Lemme try
Like that gang?
But then if I multiply by M I’ll just get an Identity what?
@random ermine
That means it’s correct
Also, for rotation matrices, the inverse is just a rotation by -theta
Yes. You rotate by theta ccw so to go back you rotate by theta cw
Oh and I got stuck because 1/det I got 4/3 instead of 1 because I forgot to add back the 1/4
Sorry guys💀
i meant simplify that for general A and B
That’s really logical right there
what i'm trying to saying (AB)(B^-1A^-1) = A(BB^-1)A^-1 = AIA^-1 = AA^-1 = I so (AB)^-1 = B^-1A^-1
My matrices are not good enough to understand this gang😭
so if M = AB then M^-1 = B^-1A^-1
hence M^-1 is the product of 2 matrices
which step
How u move the I to the RHS
A matrix multiplied by its inverse will result in the Identity matrix. That is a fact in the same way 5* 1/5 = 1
where
So BB^-1 = Identity
Right and then it does AIA^-1= AA^-1=I
And Identity * A^-1 = A^-1, so you have AA^-1 which is again the Identity matrix
Yes
But this
because AI = I
I is like 1 for matrices
Lemme process for a sec gang
Ohhhh so u just like remove the I then AA^-1 becomes identity once more?
Init🤓☝️
Waittt I get it
So smart
Which course y’all take chat?
💀
What that skull for
Did I petrify u❤️
Sorry chat😞
Yo I’m joking gang u don’t gotta do me like that💀💀💀
Already graduated
Shiittt so like in ur 30s?
Only recently graduated relax
Pure maths
stfu
dawg
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why is the horizontal asymptote not -6,6 here
perhaps they want you to enter actual equations
because -6, 6 is a point.
you'd want y=-6, and y=6
it doesnt allow that
maybe you need to separate them with ; then?
do they give instructions / a description of how they want the values
y=6 ?
oh youre right
thats weird
"," is the decimal separator
first time theyve done this
and this is why tests should either tell you the notation they want or be done HANDWRITTEN
Agree
This is so frustrating
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.then they need to learn what a comma is
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yes
M
ai spam
huh
go reread our rules and come back when you have
fwiw the approach is right
oh. yeah I think that's implicit
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Could someone plz help me w/ the circled number?
can you show rest of the graphs?
I think you first gotta find f(pi)
the graph of which I'm guessing is the one on the top left I can't see fully
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@solar gyro Has your question been resolved?
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Should c) not be 19.7<k<26.9 without the local maxima and local minima to be included as there would only be 3 real roots only and not all as it is explicitly stated?
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Bro what’s the point doing derivative if ur not even using it
Representing function as power series by differentiation
Question is express 1/(1-x)^2 as a power series
hm looks like u used differenciation
Yeah I don’t get it at all
Like isn’t that power series is representing the 1/(1-x) not even the original question??
from 1/(1-x) to 1/(1-x^2)
This is question
and ur answer is correct