#ug-maths-physics
1 messages · Page 3 of 1
kant's principle of humanity :)
least of my worries tbh
Show campus food pics
more worried abt my grades
crysto knows haha i always post on ig :)
i miss bean sprout chicken :)
Post some here. On #the-food-network
wht wht
Singapore has good chicken rice.
? food as an advice
Enjoy your food :)
owhhhhh that one ahhhh
damn bot has good taste haha nice burger
With an unusual name
ipoh food :)
coz he is smart
yi pou gai
That’s my only square meal for the week
sure or not
Channels here getting very quiet
That was a few weeks ago
fuiyoh wtf
but that means u r rich either ways u k
k is fixed or ?
but u still can afford :)
else why would u spend 40 over ringgit for a meal
maybe u ordered a drink also
k is already a factor of n!
So k|n!
And k|k
So k|(n!+k)
ye but need to prove by induction
i digest sia
wait so base case is 2! + k is divisible by k ?
It’s given that k is less than or equal to n
wait so for 3!+k then it must be divided by 2, 3?
then 4!+k , must be divided by k=2,3,4?
shitz
yes
well not at the same time
but for any given k
choose any k, and it works for that k
I am as confused as u i do not understand how tf k is a list
so do I have to do a mathematical induction inside a mathematical induction :)
or use strong MI
i still dk how strong MI works
That would be Inception not Induction 😄
there is double math induction
...which i have no idea how to do, i just know it exists
Inception is a 2010 science fiction action film written and directed by Christopher Nolan, who also produced the film with Emma Thomas, his wife. The film stars Leonardo DiCaprio as a professional thief who steals information by infiltrating the subconscious of his targets. He is offered a chance to have his criminal history erased as payment fo...
stupid q but might find the answer from a physics student, i was wondering, are air particles affected by acceleration of free fall? do they experience g (9.81) ?
good movie?
Yes very good. Recursive.
Yes but the dominant force will be electro / nuclear depending on the context since gravity is very weak
Yes, it has all the good actors and the best director too
Idk but assume gravity constant
Assume acceleration constant
Assume zero friction
Assume all strings are inextensible
Assume u can fuck with the coordinate system while the linear algebra teachers have a seizure
You know your movies well
He’s a very good director.
So if let’s say i tried to calculate the displacement of an air particle assuming it’s moving vertically downwards, would it be wrong to use acceleration as 9.81
In physics everything is assumptions
If all air particles drop to the ground then people would suffocate standing up.
HELP I LAUGHED
😆😆😆😆
Wtf HAHAHAHAY
And no gravity
What’s the answer?
If it’s A^20 + B^21 then it is possible to get a “nice” answer for A and B.
Yes
Otherwise perhaps not.
Try drawing the time graph for Inception as well as for Memento :)
oh god
this is the reply I got
"People suggested that the matrix is top triangular so there is a pattern when multiplying by itself"
Yes it clearly is top right triangular but what is the final answer?
I don't think anyone knows
Nice question
What if it’s A^20 and B^21?
Sentence on the left doesn’t seem to make sense. 🤔 @tawdry gull ?
I don't understand also HAHAH
For the circle one it's a subspace right?
Ask the lecturer!
When proving subspace, u need to prove the 3 conditions are met right. He/she is asking to prove that it is NOT a subspace, then we have to show it doesnt satisfy at least one of the conditions
@rancid schooner im quite confused if we can use the fact that detA = detA^T and det(AB) = det(A)(B) how does it equal zero??
It’s not equal to zero. You’re supposed to fill in the answer :)
Why did they set it equal to zero then lol
Yeah if it isnt seems trivial
Oh lord im fucking dumb
Thats the place to fill it in i see
😊
It’s not very intuitive. They should just leave it blank.
||doesn’t go through (0,0)?||
Yes
😊
This is the numerical solution. But there doesn't appear to be a nice analytical solution.
no one tried it
fr
Try it sometime. The solution is quite nice.
what did u use to find the solution?
oh and also, could u please check my hw6 q2b
my friend (an IMO guy) and i didnt find a way to solve it yet
Numerical search 😄
wow
Looks challenging! Will take a look when I have some time.
yes thank you 🙏
On Excel! 😄 Wolframalpha is not very good at this type of problem.
interesting
Anyway I found that the value of the leading diagonal elements is very close to: 2^ln(20/21). But not exactly so.
It should be c where c^20 + c^21 = 1.
The two edge elements are in the ratio 20:21.
Excel?!?!?
Yes. Using the solver on Excel.
Excel can handle simple matrix operations.
Anyway if you modify the problem to
A^20 + B^21 = (given matrix on RHS)
then it’s easier to solve analytically.
How would you have gone about solving it numerically?
No idea tbh 😅
You could write some Python code but it would take too much effort.
Pretty out of sync with math atm, college apps destroying the few brain cells I have left
Anyway I just wanted to see that a solution exists.
Good luck. Where are you applying?
Just submitted UCAS a couple days ago (oxford, warrick, UCL, imperial, lse) for a maths major
Working on ED for US atm
Prolly not even gonna go there considering I can't pay for uni unless I get aid/scholarship and it's pretty tough in the UK to get one
Nice. Hope it goes well!
Thx
Gave +1 rep to AlexV#1811
So it must be false
Vacuously true 
Something like "if elephants can fly, then I am Superman" hahahha
by inspection it looks like f(x) = ln(x) or something similar.
f(x) is bounded
no, it's stated that f(x) → +∞ as x → ∞
eh, it didnt
which is true for f(x) = lnx
its the sequence that goes to +infty
can we make up a sequence that follows ln(x)? i.e. xₙ = n and f(x) = ln x?
ok bounded. first line.
so some sort of asymptotic function then
maybe a logistic function
it could also not converge
Why tf they expecting a math major to do this shit
Prove by contradiction that they don’t.
philosophy channel la?
But d got contradiction no?
Bruh like
The politicians won’t be very happy with B
Oh god
I feel like this q is gaslighting me rn
Its like A is applying itself to D
AHHH
LITERALLY I DONT GET WHY ITS C
I hate ur lecturer
how did you get that?
since xₙ → ∞ as n → ∞,
(xₙ + B)/xₙ = 1 + B/xₙ → 1 as n → ∞, i.e.
(xₙ + B) → xₙ as n → ∞.
So, as n → ∞,
f((xₙ + B) → f(xₙ), i.e. f((xₙ + B) - f(xₙ) → 0.
Is this valid?
that is given f(x) converges right?
or r u assuming f can be either converge diverge?
no assumption
except that f(x) is continuous
and bounded, as given in the question
Im dumb
I was looking at the force being applied to block B not A
we also have to show an existence of a sequence that will make it converge to 0
how about {xₙ} = B ln n?
Then, xₙ + B = B(1 + ln n) → B ln n (= xₙ) as n → ∞.
Well it would work in the case where f(x) has period B.
Just pointing out the one instance where it would work :)
Not yet 😄
okay sure haha
Let me take a look again when I have some time :)
do u want a hint at least?
Haha ok
Ok similar to what was suggested in the question
ah okay haha
I think you’re supposed to prove that a sequence exists,not necessarily find a particular sequence, is that right?
Fellow math gods
How to develop math intuition to solve math problems :')
N the proofs
Coz
I suck :')
And I wanna die coz I'm not cut out to study math

exactly
umm, there are visuals for some math concepts
which would help
Otherwise how would you know that 1+1 = 2?
Where ah besides trusty old 3b1b :')
Smh
Common sense? :)
Must start from axioms
Guys
I have a discrete math mid term tonight
And I cant stop wondering how this subject is actually useful
Plz someone tell me any famous use of discrete math
useful in cs
especially cs deals with discrete things
uhh considering this chat is quite active could someone please help with this MAT question?
(e)
||Simplify to (sin y)(1 - sin y) = (sin x)(1 - sin x)||
|| then solution is x=2n𝜋+y, 2n𝜋-y for integer n ||
nice question
i got till here but couldnt think of the next step
thanks
Gave +1 rep to AlexV#1811
😊
The other element of the solution (not required in the question) is ||sin x + sin y = 1||. Visible when you plot the graph.
Combinatorics. Which is fun as well.
Like the CROCODILE question 😄
you are no longer my friend
What discrete maths topics are you doing?
very first chapter, propositions, inferences, predicates, quantifiers, intro to proofs
That sounds rather dry
Yea p much same here
I failed my discrete math midterms :')
😭
stop scaring me bro
if you wanna pass then you study
Dw you'll pass
studying is necessary for passing
Necessary but not sufficient
either you study or dont pass
you cant pass and not study
let the argument be that if you wanna pass then you study and you didnt study therefore you didnt pass
Modus tollens moment
true for all students
Hold a study session
uhh second part??
do they mean like ||the point (a,b) say lies in S such that it itself is its nearest point?||

That would be one nearest point
Perhaps S is the subset of points on a circle with centre (a,b).
the subset has a non unique solution that is nearest to point (a,b)
as alex mentioned, a boundary of a circle with centre (a,b) would work
since there are infinitely many points equidistant to (a,b)
so there is technically no "nearest point"
or an empty set would work too, an empty set by definition is a subset of any set
then what about iii) wont a circle with centre a,b work for that?
oh yep
thats for iii)
or an ellipse centred in (a,b) would too
for ii), any open set would work actually
as long as it doesnt contain (a,b)
Where is this from?
the open set?
x^2+y^2>1 would be considered an open set right?
yes
just make sure it doesnt contain (a,b)
so u can make (a,b) the centre
(x-a)^2 + (y-b)^2 > 1
AHHHH i got it know, they meant there's no one point that is nearest right?
wait no
So that’s the empty set
in this case all points on the boundary of the region will be closed to a,b no?
closest*
oh fudgee
thx
Gave +1 rep to The_Pierrot#7889
gotcha
So for any point that is close you can find a closer one
sheesh mat is hard
Like an infinity pool
and thx @rancid schooner
Gave +1 rep to AlexV#1811
😊
i dont think i'll be able to prepare for mat in 10ish days
college apps and school exams are killing me
ooo will check it out
Watch Oxford Mathematics Plus videos on YouTube by James Munro.
oh i see
A nice MAT question was this: what is the maximum value of (ax+by) where a, b are positive and x² + y² <= 1?
no other restrictions on a and b?
No
Guys how does Universal Generalization work 😭
how does the argument P(c) conclude that ∀xP(x)
Could u send me the questions if you have them?🥺
Concordia, Canada, Data Science
Nice. Good luck with the course!
Uni mathematical induction next level compared to furthermaths 😭😭😭
technically induction can be done as long as it proves along the integers so... :D
there is also math induction on a chessboard
classic example of recursion
and also classic example in a course on theory of algorithms
Tower of Hanoi does bring back epic memories of grade 8 me cracking the optimum algorithm my second try of playing
Can't relate, in grade 8 I was still dumb af 
Can anyone help me out with this? Proving it is a subspace, I have a LA quiz tmr😭😔
Idk how to prove that this satisfies closure under scalar multiplication
.
This was my approach:
S={(a-c,b-c,0); a-c∈R, b-c∈R}
We can rewrite it as
S={(x,y,0); x,y∈R}, where
x=a-c
y=b-c
this is a x-y plane in R³ which contains the origin
Idk how to do exactly this 😭 help pls🥺
let v be in S, then tv is also in S
for any real number t
u will get ta(1,0,0)+tb(0,1,0)+tc(-1,-1,0)
if t>=0 then it immediately follows that tv is in S
if t<0
Ye? 🥺
let u=-t so that u>0
ta(1,0,0)+tb(0,1,0)+tc(-1,-1,0)
= ua(-1,0,0)+ub(0,-1,0)+uc(1,1,0)
= uc(1,0,0)+uc(0,1,0)+(-ua,-ub,0)
= (uc+ub)(1,0,0) + (uc+ua)(0,1,0) + (-ua-ub,-ub-ua,0)
= (uc+ub)(1,0,0) + (uc+ua)(0,1,0) + (ua+ub)(-1,-1,0)
all ua, ub, uc are nonnegative
so its in S
Uh wait why not (uc+ua)(1,0,0) ah
Hold on lemme digest digest 🥺
oke
Thank u LIFESAVER
Gave +1 rep to The_Pierrot#7889
okeh 👍
what is this shit bro?
what language
Subspace
great, now Im scared of studying linear algebra too :(
Why cant math just be calculus
cuz calculus is not enough 😭
Exactly
Don't worry you didn't pick maths like me :')
miller miller
What is that object to the right of the whiteboard?
Idk tbh
Did I choose the wrong course :")
Don’t believe everything you read
Ask the lecturer
senpai should guide us
Ask @tawdry gull 😄
But how u so sure math is right for me :')
I'm like dying in LA
I can't write proofs
Which is the essence of math 😞
Just copy from sample solutions as an exercise and you’ll get the hang of it
So your advice is copy solutions to master proofs ah
I copy alr still shit
😔
Bro I can't even teach myself
Probably EᵀM or something like that
Ci -> Ci + c Cj ?
4 marks :')
other marks come from explanation :)
ME is basically the rows of M multiplied to columns of E
which basically means column i of M becomes Ci+c Cj
because in E, column j has a c in it
Yeah idk why people dont talk about this
People jus say “just do the proof bro try not to look at solutions”
Learn by imitation. The first few times at least.
But what if the qs are so diverse
That you can't find any pattern in it
Well ur not trying to find a pattern
Yeah but idk how to justify :')
More like developing a thought process
Idk how to get that man :')
What do they teach during tutorials?
We have a maths club and if u join free coffee not sure if that counts 🤣
Free coffee! How nice 😊 ☕️
Man they call it “elite”
tutorial just discuss problem sets
I rlly think I'm not cut out for maf :')
wine and cheese party exists
Now I feel like having wine and cheese 🍷 🧀
Are you a participant?
nope
only chern class students get to do it
which im not
or maybe not yet
who knows
i dont have high expectations
Not yet.
Anyway you can still buy wine and cheese for yourself.
Maybe we can have a ZNotes wine and cheese study session 😄
doobee's dumb qs
help needed
X/Y = 5/7
Y - X = 24
Solve da equation
Needs to be solved by some ratio method
The topic is ratios, percents and proportions
What grade are you in btw?
Wow who would have thought differentiation would be so complex 😄
wouldnt be fun if differentiation is just the way it was
hahaha
try doing 1b
its nice haha
cos² (πx/2)?
it is decreasing on [0,1] :)
The optional part on Hermitian Polynomials looks interesting
1b must be decreasing on the whole domain
So it’s valid for 1a
Haha yess
😊
Monotonically decreasing?
yes, not strictly tho
do have fun with the questions haha
Please host a study session for this channel
elloooo..how to approach this question after finding the solution space of S xD
Help needed <@&597104882482413589>
I thought it was asking for the max. and min. values the graph can yield
If you're looking for the point where dy/dx=0 its quite simple: x = -2.4
But theres ofc more to it than that bcuz its 10 marks TT
No wait
thats quite dark aha
mmm icic
pngs :/
:(
the abs maxima could be -1 or -5 too
yeah
Well in that case, u have one local max, we can check if its a min/max later.
In the range x = [-5,1], the graph is always negative (because for terms to the power 2/3, you're squaring it and then taking the cube root so its a positive number. Then you multiply by x which is negative)
If you have a term s.t. f(x) = 0, that will be the absolute maximum.
From the dy/dx equation, theres a certain point where we cant evaluate dy/dx, try using that value in f(x) and see what u get
bruh u spoiled it for him
Ah shit, lemme hide it
||Looks like absolute Max is where y = 0 which looks to be -4
and absolute Min is f(-5)||
@blazing wraith
Okok tq tq! I thought it was way more complex
For the absolute minimum, we can check that when dy/dx=0 is a turning point, it is the local minimum. To find if its the abs minimum, compute x=-2.4
Then, using the graph of the derivative, you will find that the point where dy/dx = 0 is local for a certain domain, now check if thats true for the remaining domain (by subsituting the most extreme value of that domain ie. endpoints, and then compare)
If ur not going to use a calculator, its helpful to write dy/dx which ive computed earlier as: 1/(x+4)^1/3 * (5x+12)
@verbal nova @unique zodiac thank you so much! ill have a look and if thers any questions ill ask you guys again :D
Gave +1 rep to Brave#5303, ukan#9821
but then, how did you get 2x/(x+4)^(1/3)
i cant understand the way to derivative, i thought outside bracket then only inside
Oh, here I'm using the product rule, so bcuz u have (3x)*(x+4)^1/3 , u have to use the product rule
you forgor A2 math?
haha kinda LMAO
💀
moment
For the first part im sure uk how to get, for the second part its: 3x * 1/3 * (x+4) * (1/3 - 1) * (d/dx x+4)
@blazing wraith hows data science 😎
awesome for now but some places kinda drowning cuz bad lecturer
me trying to study by myself haha
uni life 101
every subject is killing me
yea im bad at calculus
whats the subject called?
calculus 1
3D calculus 
damn :o
so is this correct?? or is there anything missed out
@verbal nova @unique zodiac
actually from the graph I sent, the abs max appears to be f(-4) = 0
u got the min. value correct which is cool
but yeah the abs max is (-4,0)
ur right in assuming that if the turning point isnt the local max/min, then one of the endpoints would be
Here we only have one turning point which is a local minimum, then one of the endpoints would be the abs. minimum (if the turning point isnt). It doesnt tell us anything ab the abs maximum.
how would you know the abs max is (-4,0)? what calculation can help you to get it?
Yea lme guide u there
Heres sm food for thought
If u show that f(-2.4) is a minimum, isnt it weird that f(-5) is somehow lower?
Bcuz u didnt find any other turning points, so its quite strange that f(-5) is lower than f(-2.4) isnt it
Now think: How is that possible, between -2.4 and -5, how did the derivative suddenly flip signs? Where could it have happened? (Hint: Look at the expression for dy/dx)
Ig making a graph
what 💀 bro
just make a graph
chii in the exam
HAHHAHAHAHAA
Unless u cn use a graphing calc in the exam, u have to get it analytically somehow
i have no idea 😭
dy/dx = 1/(x+4)^1/3 * (5x+12)
here its not possible to get a derivative at the point x+4 = 0, x = -4
But the point on the graph does exist, so u have to see what happens there
You guys took F Math?
no :(
in AS we had a whole chapter for making graphs
yea but u dn need to make a graph here
Okay tbf if it does help u then its fine
But b careful and see if graphs are an accepted form of working
do u mean like we find the valyue of x at here, that make this equation 0 , ie:(x+4)^1/3
What I meant to say was, find the value of x such that the derivative doesnt exist
So bcuz dy/dx = 1/(x+4)^1/3 * (5x+12), we can see that if the denominator is zero, the derivative wont exist
So this only happens when (x+4)^1/3 = 0, x = -4
Its a little tricky to explain, but bcuz u can show that at x=-2.4, we expect the y-values around it to be more than f(-2.4) right?
But somehow f(-5) is less than that, so that means that there is a turning point that we didnt find, OR there is a discontinuity in the gradient
In this case, we find a discontinuity and the point where the gradient is discontinuous will be a max/min
In this case its a max.
I hope that helped, this q is a bit big brain if ur doing it strictly w/o graphs
lemme digest, but i should be able to get it
means discontinuity gradient will also be either max and min
right
I meant that it could possibly be a max or min, it depends on the circumstance
As I said its a little difficult to explain
Next time u encounter a q like this, think ab this thought process
Its important to consider gradient discontinuities
yeaaa thank you again @unique zodiac
Gave +1 rep to ukan#9821
alrightttt
Hi guys xD does anyone know how to approach this question for Tp M subset.. This is the second part of the question.. M is a vector space for 2 × 3 matrix in this case
The thing for me is.. the AP=PA condition doesn't make sense to me cuz AP= 2 by 2, while PA should be 3 by 3
I also thought of alternative approach like A=P^-1PA, but since neither of them is a n by n matrix, this won't work
why here so quiet :(
also found this in a coding textbook but i'm curious about the maths approach to it :P
Help needed <@&597104882482413589>
Let's say you have vector u v and w. u=(-1,2,0) v=(4,1-3) and w=(10,-2,-6). How do you know when to use Gaussian elimination to find if they are dependent or independent
What is M in this case?
If A is 3x3 then AP = 3x3 matrix and PA = 3x2
Hmm thats odd
Well, if one is obviously a scalar multiple of another, then you dont have to use gaussian elimination. Otherwise you do
Its not like u need certain criteria to use gaussian elimination
You can apply it on any 3 vectors to see if they are linearly dependant or not
oh ok, thanks
this is kinda brainfarting me XD
The whole question b is just odd hahaha
Ap=PA is clearly unsolvable? They can't be equal?
Can anyone explain how vectors u = (4,-3,0) and v = (5,0,2) are coplanar, they are not on the same plane, one has a z value, but Ive been told that 2 vectors of R3 that are brought back to the origin are always coplanar. What does that mean?
Help needed <@&597104882482413589>
It’s possible that they’re equal
But thats not the main focus of the question
Hmmmm
But to show that Tp is closed under addition.. Oh wait ya
在死路了hahah
😩
I think I got it.. But it has to satisfy that condition given isn't it
mhmm
Hmmm
||(A1+A2)P=(A1)P+(A2)P=....||
Tq tq! 
:)
Because πerrot would come up with a good answer 😄
still learning :)
Rite
Machine learning 😄
Hmm how to find the image of matrix HAHAHA
Put it in front of a mirror
wha idgi, ur getting a 3x3 matrix on the lhs but a 2x2 matrix on the rhs
If u look at the parametric definition of a plane: r = p + λd1 + μd2
p is a point, d1 and d2 are directions. You can take any 2 vectors and they can be coplanar, choosing an arbitrary point
Samee so is part b a subspace or nah?
If it's not then one of the axioms must fail right? (First axiom in this case)
Since Tp is a subspace iff it satisfies the 3 axioms isn't it 😭
can someone help with this one
Yeah that's wht I thought..
Yeah the first condition zero vector thingy is not satisfied.. If not wrong
Please do a study session for university matrix maths
Try asking ur prof abt it
Is b a function?
\
can you help me figure out what i did wrong
the actual answer based on the solution sheet doesn't have the /e^t but i don't see how to negate that
no because undefined when n=pi
functions need to be
- defined in the domain
- has only one output
Is 1/x a function?
for x =/= 0
Ok so a function has an output for all values in the domain
Alright, thank you!
Gave +1 rep to The_Pierrot#7889
Yes, they the same
so is philosophy
so No Phy role?
There's a UG physics role but they both lead here
XD i was have a friend who took philosophy elective their beginning syllabus was so similar to logical propositions in Discrete Meth
All mathematicans are philosiphers but not all philosiphers are mathematicans
true fact
Is the inverse function even possible???
Help needed <@&597104882482413589>
I assumed there was and got [1/3, 2/3)
But now im wondering if it is injective or even surjectuve
Help needed <@&597104882482413589>
probably I guess? Cuz I saw this equation during my IIT ¯_(ツ)_/¯
Bro didnt u start AS this year
I Study JEE Too
But u werent able to solve an AS trig question yesterday…
cuz trig is said less
not a lot
only basic he said
@long aurora u were guys like made me confused
I see
I started in June 13th
$\frac{d}{dx}e^{tanx}=$
Unknown Member
Help needed <@&597104882482413589>
what's the answer?
$e^{\tan x} \sec ^2 x$
Acid
The derivative of $e^{f(x)}$ is $e^{f(x)} \cdot f'(x)$
Acid
Ty
btw do you guys have any youtube channel recommend for discrete math? Also help my peanut brain xD I think c and d is equivalent but I am not sure about the rest (Question 4)
D
a and b are possible but not equivelent
oo ok
I have a question xD.. Is there a way to compute the determinant of 6*6 stochastic matrix?
I have to prove that the eigenvalue is 1,since a stochastic matrix should have an eigenvalue of 1 and have a stable distribution
Yeahhh xD
which axiom justifies that if x = 1 then x + 1 = 2?
or in general which axiom justifies 'doing the same thing to both sides'
field axiom
Thx👍
Gave +1 rep to The_Pierrot#1126
https://en.wikipedia.org/wiki/Singular_value_decomposition very interesting topic which came out in my assignment
how to do 1b
Help needed <@&597104882482413589>
i need help plssss
It’s greater than the integral of x² from 1 to 3 which is 26/3.
i dont get it, can you elaborate further, by using the theorem pls @rancid schooner
From the graph in part a the √ graph is above the x² graph. So its integral cannot be less than the integral of x².
so how could we proof that the integration will be more than 26/3?
Because the graph is higher
Can anybody explain what does Y means?
f(x) = y
Set X is the domain
Set Y is the range
basically, words
Y is the set of words using the english alphabet
doesnt have to be english words
it can be "aksdghasjgkdash"
thats also in Y
the point is that it's non-null
ohhhhhh
Oo ok got it thank you!
Can anybody help? I don't get this 2 questions
Q6: int(1000/7) + int(1000/11) - int(1000/77)
oo ok thank you!
Gave +1 rep to AlexV#1811
😊
Guys, may I know why f(x) is not onto? |B| <= |A|
I thought it should be
Or f(x) should be integer? And not N?
f doesnt map to all the naturals
a quick example, there is no such x in N such that 3x-2=2
2 is in the Naturals, yet we cant find a natural number x such that 3x-2 becomes 2
so it is not onto
It will be a quotient not a natural right??
yes exactly
For (iv) it does not exist because all natural numbers are +ve but intergers cld be either
Ohhh got it thank you!
Gave +1 rep to The_Pierrot#1126
https://www.youtube.com/watch?v=ngCos392W4w
I highly recommend this video for problem solving, I used this videos techniques yesterday by testing out multiple cases and finding a pattern in my discrete math exam in a question that is not even related to recursions
In this video, we take a look at one of the more challenging computer science concepts: Recursion. We introduce 5 simple steps to help you solve challenging recursive problems and show you 3 specific examples, each progressively more difficult than the last.
Support: https://www.patreon.com/reducible
This video wouldn't be possible without the...
Help needed <@&597104882482413589>
Volume = Cross sectional area multiplied by distance travelled by centroid
There are a lot of people in the world and a large number of them are very lonely. In this video I address the topic of mathematics and loneliness. I try to provide two solutions that might help you fend off loneliness. Do you have any advice or opinions? If so please leave a comment below.
I will also show you some of my math books. The books ...
Hopefully this is not true
why did he sniff a textbook😭
perving out on a book ffs
If we ever end up doing that, we are long gone
Add (2-√3)²⁰²² then subtract 1 to get the integer part.
Wait why though?
That's to find the integer part. Standard A-Level binomial expansion question.
To find the first digit to the left of the decimal point, first let 𝛼 = 2+√3 and 𝛽 = 1/𝛼 = 2-√3.
Note that 𝛼 and 𝛽 are roots of x²-4x+1=0.
Is that enough of a hint?
Would you like me to continue?
N^2022 + (1/N)^2022 - 1 ? Nani?
Will put the rest in spoiler below.
||Let Sₙ = 𝛼ⁿ + 𝛽ⁿ, and note that Sₙ = 4Sₙ₋₁ - Sₙ₋₂, and S₀ = 2, S₁ = 4.
Computing Sₙ mod 10 iteratively for successive values of n shows that
Sₙ mod 10 = [2,4,4,2,4,4,2,4...] for n=0,1,2,...
i.e. Sₙ = 2 if n=3m, and 4 otherwise. Since 2022 = 3(674), therefore S₂₀₂₂ mod 10 = 2.
Also, since 0< 𝛽= 2-√3 <1, therefore 0<𝛽ⁿ<1.
Hence the digit of the left of the decimal point is 1. ||
Yes, but it's a very big number :)
Extra credit: What is the digit to the right of the decimal point of (2+√3)²⁰²²? 😄
To get the last digit
But S_2022 is α^2022 +β^2022 right? How does dividing by 10 give the left digit next to the decimal point of α^2022?
α^n on its own is messy so we pair it with β^n to get an integer which is easier to compute
Yes. But since β is between 0 and 1 β^2022 is also between 0 and 1 (and much smaller than β).
We know α^2022 + β^2022 is an integer. So the integer part of α^2022 must be 1 less than that integer.
Oh so something like finding the floor value of α^2022 ah 😂
Im guessing 9 HAHHAHA coz I kept pressing my calc :)
Your calculator is unlikely to be able to handle that haha
And coz the beta thing gets closer to zero for higher powers of beta :D
Have you read my spoilered solution?
Yes bc I forgot all my further maths stuff
:(
Thanks math god 🙇♀️🙇♀️🙇♀️ @rancid schooner
😊
Haha maybe they removed it or perhaps you have to reply
Thank u maths God🙇♀️🙇♀️ I'm relying on you to carry my gpa when my tutor graduates 😂🥺
Gave +1 rep to AlexV#1811
Yes both of u 😭
I had to retake foundation of maths coz my midterms score was below avg 😭😭
Which topic is this question under?
It was my friend's discrete maths midterm
That’s ok. That means you’ll have a stronger foundation :)
You’re not taking discrete maths?
Looks like a flight number
This is designed for the comp sci students
And this is for the maths students like moi but I'm too dumb 💀
Did your friend solve it?
One of them did but they on vacation now
Still waiting for their reply ahaha
Why are you doing your friend’s exam even though it is over? For practice?
Presumably exam means in-person exam.
Anyway hope that was helpful :)
Curiosity😂
Yessir
Yep
Now try the extra credit part :)
Btw out of curiosity, how to be absolutely sure that the pattern doesn't break tho?
Yes 😄⭐️
What do you mean?
The 2,4,4?
Yess
It’s cyclic. So you just have to prove it for one round.
Prove by induction or?
Don’t think that’s even necessary
So how to go about proving it ah :(
See above
Hmm ok thank u sifu amongst sifu🙇♀️
Thanks rep +1
Gave +1 rep to AlexV#1811
😂😂
It was a fun question 😄
😊
Here’s an idea. Why don’t you do a reverse study session? You livestream your attempt and then people can give suggestions.
I'm too dumb to even think of a solution in the right direction😭
You can just ask for suggestions for the next step
is Limits done for u guys?
Is gigachad asking moi? 😂
Nani?
dQ and Sasuke are friends?
What if the expression is
(√ 2 + √ 3)^2024?
I'm boosting this server -.-
Looks tricky 😄
no way out of all people you find smthn tricky
He'll have to use 1.1 % of his power now instead of 1%
Question origin: ||Tokyo university math entrance exam for medical students||
||are you thinking of switching to medicine?||
No thanks 🙏
😂
If this is a medical exam qn
What are engineering qns like 💀😭
Mathematical Medicine
But why
Lmaoo I have a friend, first year medical, and he asked me a couple of times to help him in probability questions
Bayes theorem and combinatrics and shit
They’re meant to do difficult work under time pressure
U dont want medical students who couldnt think properly under time pressure dont u?
That wld be a mess💀
Lmaoo i saw the video just yesterday
:v
hey
do you guys know where can i find university physics book by young and freedman
i have it, do u still need?
required course 🤷♂️
yes
Yes to experimental?
we have experiment course for it too
Interesting
Help needed <@&597104882482413589>
Basically, I've done A levels and started undergrad maths
They got something like let's say MATH A and MATH B
So MATH A I exempted since I did a levels and I am on MATH B
Math a was the prerequisite for MATH B and it seemed to just be A levels
....
To get to the point
I've done integrals
Buts what's this thing with E and then n --> infinity????
By E I mean the sigma sign
He’s probably referring to the epsilon-delta definition of a limit.
seems so
Can you send a pic of the question?
just need a small hint w this :') @mathgods
Triangle inequality
Yea thought of that too but like I think something’s off here, idk how to get there
$| \sum f(x_i) \Delta x| \leq \sum |f(x_i)| \Delta x$
The πerrot
OH FCK HOW COME I DINT THOUGHT OF THAT T-T
or u can use the fact that $-|f| \leq f \leq |f|$
The πerrot
this one also eventually have to use reimann sum?
nope
just integrate all sides and conclude into one single inequality
hmm ok i try try first thank uu
Gave +1 rep to The_Pierrot#1126
but how to integrate modulus f ah :(
ikr p sure this sem my gpa gonna drop until cannot afford economy rice T-T
er and also for this right just ignore the lim n-> infinity for reimann sum ah
and just say approximation? idk sounds weird tho
That 比喻🤸♂️😵
means modulus this part but on the RHS the modulus technically has no effect? coz all the areas are positive?
f can be negative?
Uh huh?