#help-49
1 messages · Page 229 of 1
yeah, then its right
You a legend
np
.close
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oh perhaps one more thing, dont write 0 <= x <= 3. Write either ran(f) = [0, 3] or 0 <= y <= 3
oh and since x > 0, you cant even reach 0
nor can you reach 3
so it should be 0 < y < 3
not <=
if you can use that, then it should be possible with it
graph it and eyeball the range from the graph
if its allowed on the exam, then its not cheating
Cost 2 bills 💀
but I'd double check whether graphical calcs are allowed
Yh they are
then you're good
.close
it's closed already, should disappear in few mins
Alr, might need your help tmr at sum point till then brother
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¿Que has intentado?
!muéstra
y podriamos usar las imagenes para obtener la funcion
tipo,
f(x) = (0,2)
f(y) = (0,-2)
f(z) = (1,2)
f(w) = (1,-2)
is an idea a bit algebraic but
say for example
no I have no idea
I thought I had something but, I dont think it will work
Is I the set of irrational numbers?
no
What is I then?
oh
well no, I think its the domain
@torpid garnet
well, in this case, the function is a parametrization, where I is an interval of the domain
no?
like r is a parametrisation, where I is the interval the parametrisation is defined in
no?
for example, find r(t) where t in I
at least from what I am interpreting, maybe there is a misunderstanding
"I a subset of R(reals)" typically means "I an interval in the reals"
whats with that wires emoji
someone recognized his pfp and reacted with a matching emote
I dont have a pfp, so cant relate
@tidal turret Has your question been resolved?
translation pls?
a parametrization? this shouldnt be the case. A curve should have measure 0
that is: if the function is continuous, it shouldnt be possible
whats with the measure zero topic?
this is not measure theory, terry tao
im just saying that it shouldnt be possible if you mandate r to be a parametrization
oh it was unclear in the translation i thought its the whole rect
yeah i would argue the og question itself is a bit unclear
Do you know how to parametrise a segment?
NO
The most common way is with a baricentric parametrization
can you explain
r(t) : (0,1) → R², t → (1-t)·(x0, y0)+t(x1,y1)
If you see that is a segment that goes from (x0,y0) to (x1,y1)
what is a baricentric
A baricentric combinatio of x1, ..., xn is like a1x1+...+anxn with a1+...+an=1
In our case, 1-t+t = 1
a linear combination or something
With the propery that the coeficients add up to 1
🤔
and the terms are usually points not vectors
i dont follow
what should I do now?
why is the question not specific and vague?
I dont think I understand
I dont think I follow
You have to write a fucntion that goes all the way round the rectangle of that vertices
A parametric curve in specific
r(t) : (0,1) → R², t → (1-t)·(x0, y0)+t(x1,y1)
If you see that is a segment that goes from (x0,y0) to (x1,y1)
So in this case you have 4 segments
what does this mean in human ?
You can think of a way of adapting and concatenating
what?
the parametric curve is from I which is a subset of R to R2
r : (0,1) → R², (1-t)·(0,-2)+t·(0,2) =
= (0, -2+2t+2t) = (0, 4t-2)
this is the segment that goes from (0,2) to (0,-2)
how does that work?
im not sure i follow the notation
can you elaborate on the simbology
r : (0,1) → R², (1-t)·(0,-2)+t·(0,2) =
= (0, -2+2t+2t) = (0, 4t-2)
this is the segment that goes from (0,2) to (0,-2)
Think of what happens when you substitute t=0, t=½ and t=1
Maybe that helps
how do you know the interval of the parametric curve is between 0 and 1
That's standard for standalone segments
maybe think of it like a weighting so if t is 0.25, r(0.25) is 75% (0,-2) and 25% (0,2)
(And more generally for natural parametrizations but that is not a topic you should learn now)
in this context i think you can decide what I is
Categorist made a convenient choice
Yes and he might change it so he get the rectangle more easily in an intelligent way
the problem categoric, is that i don't understand the parametric curve you sent, why (0,1) -> R2
Look at this:
r: (1,2) → R², (2-t)(0,-2)+(1-t)(0,2)
that would also work
That is a good hint for you
Look at what happens when t=1, and t=1,5 and t=2
(0,-4+2t) + (0,2-2t) = (0,-2)
(1,2) segment (0,-2)
i dont think i follow the idea
This is a different parametrization for the same segment that which goes from (0,-2) to (0,2)
Have you tried this?
Ok do this
yeah trying points will make it more clear how the function maps points in [1,2] to one of the side of the rectangle
ahh the interval is [1,2]
of t
r: (35, 36) → R², t → (35-t)·(0,-2)+(36-t)·(0,2)
Substitute t=35, t=35,5 and t=36. What do you see?
he changed I but the image is the same side of the rectangle
t = 35 is (0,2)
So the idea is parametrizing a side on (0,1) the next side on (1,2) the next side on (2,3) and the next side on (3,4) and sum them all on the union (0,4)
I=[1,4] with a function defined by parts
And yes it would be closed intervals. I'm so used to parametrising with open intervals bc of calculus, sorry
now thinking about it would be [0,4] but same idea
how did you managed to find a formula based on t for the segment
It's common knowledge, baricentric combinations I learned at uni when I was sophomore
i like the intuition in term of weighting
but i’m not sure you got the idea renato
Yes, it is useful and there are gif on the internet for the triangle case
very visual
image for this sentence
yeah im newbie, like I started a week or so, university
how does the formula for the segments do that, then we union the segments?
you have to define r(t) in four parts
life is tough dude, uni is eating me alive
and then what?
wdym in parts?
as far as i am aware, multivarcalculus is usually a very full course, like there is a lot of stuff to cover in short amount of time
uni is like that sometimes unfortunately
mine was like that too, i survived and was rexeposed to the ideas later during undergrad
THIS, @tidal turret
smt like this
can you mark the points?
of the rectangle
well, the most important part is how to get to the parametrisation of each segment or sub interval @shadow schooner @torpid garnet
like this (1-t) ...
you guys said baricentric what?
baricentric combinations or something?
the interval for t in [0,1) is the segment of (0,-2) to (0,2)
but how do I found a formula for the segments is what I am asking, a parametrisation of the segments or sides of the triangle
@shadow schooner @torpid garnet
I sort of have an idea
say you have a generic point, (x,y)
(x,y) = (1-t).(0,-2) + t(0,2)
nah, I dont follow dude
yes, how to get to find the formula dude
i follow what you guys mean, but I get lost in the baricentric part dudes
do you agree when t=0, r(t) = (0,-2) and when t=1 r(t) = (0,2)?
initial point (x0, y0)
final point (x1, y1)
variable t
interval (a,b)
formula
r(t) = (b-t)(x0,y0)+(a-t)(x1,y1)
ok, that clarifies a lot
I don't know it by heart I know where it comes from and deduces it anytime I use it. Maybe you don't know, but you will
i appreciate the help
but
there is a simpler way I think
just, we have 4 points, we can create 4 lines
let me do a drawing
basically, each of this 4 lines passes through 2 points we will use parametric equation of a line
then, we figure out the intervals for t
but first let me draw and explain
knowing two point a line passes through we can find the line L1
L1 : X = t.((0,2) - (0,-2)) + (0,2)
L1 : X = t.(0,4) + (0,2)
then we write it as a generic point in R2
L1 : (0, 4t + 2)
now we need to find the interval of t such that (0, 4t + 2) passes through (0,2) and (0,-2)
that will be t in [-1. 0]
easy right?
yeah this works also it’s a direction vector + starting point approach
you can find similarly the other segments
exactly dude
but my guess is yes it will work but it will be clunky to get the precise interval you need
it’s not that i believe this is more efficient for that problem
plug and chug and extra point if you get the intuition
it surely is, but my approach uses less machinery, it would depend if you like complexity or simplicity
anyways, I dont want to bore yall, I just wanted to mention other approach
try your thing and see for yourself
are you going to watch me or should I close?
we can always go back to categoric solution
i can watch
ok
Let A = (0,2), B = (0,-2), C = (1,2) , D = (1,-2) be points in a rectangle!
LAB = t(A - B) + A = t((0,2) - (0,-2)) + (0,2)
LAC = t(A - C) + C = t((0,2) - (1,2)) + (1,2)
LBD = t(B - D) + B = t((0,-2) - (1,-2)) + (0,-2)
LCD = t(C - D) + C = t((1,2) - (1,-2)) + (1,2)
LAB = t(0,4) + (0,2)
LAC = t(-1,0) + (1,2)
LBD = t(-1, 0) + (0,-2)
LCD = t(0,4) + (1,2)
LAB is (0, 4t + 2) and needs to pass trough A = (0,2) and B = (0,-2)
thus, t = -1 and t = 0, so t in [-1, 0]
LAC is (-t+1, 2) and needs to pass through A = (0,2) and C = (1,2)
thus t = 1 and t = 0, so t in [0,1]
LBD is (-t, -2) and needs to pass through B = (0,-2) and D = (1,-2)
thus t = 0 and t = -1, so t in [-1,0]
LCD is (1,4t + 2), and needs to pass through C = (1,2) and D = (1,-2),
thus t = 0 and t = -1, so t in [-1, 0]
finally we get
,, r(t) = \begin{cases} (0, 4t + 2) \iff t \in \left[-1, 0\right] \ (-t + 1, 2) \iff t \in \left[0, 1\right] \ (-t, -2) \iff t \in \left[-1,0\right] \ (1, 4t + 2) \iff t \in \left[-1, 0\right] \end{cases}
Renato
this is good apart LAC t=-1 to t=0 (typo?) for parametrizing each line segment individually
@shadow schooner
?
LAC has t = 1 and t = 0 dude
ahh I see what you mean
we are re using the same intervals
like yes
maybe it’s me whose tired on this one
nah dude, im also tired asfk
I went for the gym for 2 hours dude
nonstop in the treadmill
but for this exercice this won’t do because it’s not a function same input gets sent to multiple outputs
yes
I guess we can re do with better direction vector
and better point that the line passes through
you could try to tweak the starting point but it will get annoying though perhaps you will end up with a formula
tbh idk but seeing those two way to parametrize line is good
theoretically speaking if we would have chosen better line equation we couldve gotten a unique interval
is just that I hate this trial and error course
everything is so applied and with applications
maybe im just coping at this point, idk
heads up you will probably do integrals on those kind of line segment later in this course (was covered in mine) and you can do each one with it’s own parametrization
what i feel they do is they make you play and familiarize yourself at the start with the object you will differentiate and integrate later in the course
so it feels arbitrary right now but it will pay off later type thing
maybe, im just been eaten alive by uni
is like first week or so and I am already struggling, tips?
Im going to be honest, I feel like I might need to retake this one, ngl
don’t say that already, you didn’t even had your first midterms yet and you seem to grind hard.
that’s one of the thing i disliked math undergrad for. you get blasted this very large amount of information and you get the feeling you can’t appreciate what it all really means
you learn to prioritize things, exercises part of lecture notes, you somehow have to guess what the midterm will look like and study for that based on cue from the teacher
those are like general tips
having people to compare homework or study max 2-3 is insane also if they are good
I am so antisocial, unless I meet a nice goth mathgirl I think I will be studying by myself dude, math is lonely
tbh i’m not sure i would call this approach barycentric smt. for me it’s called a convex combination.
In convex geometry and vector algebra, a convex combination is a linear combination of points (which can be vectors, scalars, or more generally points in an affine space) where all coefficients are non-negative and sum to 1. In other words, the operation is equivalent to a standard weighted average, but whose weights are expressed as a percent o...
tbh, there are no better helpers sometimes than the other rats in the gulag with you
but my undergrad was very small
like 15 peoples
dude, the day I entered university we were only 4 people counting me in my class, that was starting math this semester
there are a lot from other years, math students, math dept is not small, but in this semester only 4 people were starting math major, for compsi it was like hundreds
I just hope I can find a nice girlfriend dude
who is also interested in math
k so it’s different maybe if you struggle to the higher math class late undergrad, what i said about having this kind of math friend will apply more. (call shots for exam, give you deep insight on concept or find the trick in the nasty proof at the end of hw)
i would’nt limit this to a (perhaps nonexistent) math girl. if you spot someone you will seemingly share a lot of hard classes with and they seem pretty good, go get them
yeah Im open to it, the day we were welcomed, the other 3 people one was a cute girl, hopefully I can make her my gf dude, she is also studying math, then we can talk about math no problem, about having male friends, well, im not so interested, i can always ask TAs for help so its not a biggie
the 2 other rats i found first semester helped me so much even if they were not there at the end of my undergrad
but tbh this is getting pretty off topic
i need some sleep dude
rats = friends










I appreciate the help dude, well its whatever
just hope I can find some gf dude
its funny the rat and the gulag analogy you do jajaj
😭
type shit
all of my advanced math courses are just men
what would you say its advanced math?
go for it
i mean like the advanced courses that are intended for advanced/promising undergrads
only ones math majors take
who want to go for a phd
damn, seems tough
but i’m sure you could find women in stem classes
girls do engineering
cs
💀
wdym?
your school doesn’t let them?
i thought you said you just met her
well, love at first sight
I cant find her
the first day of university the profs welcomed every group of people by major
we were four who started math major this semester, one was me
well, its complicated, I am also doing cs
but only in case I am not able to get a job or something
but basically, our first year courses are so general so, every course has like 300-400 studnets
yea my first semester was like that
i haven't seen her since day1
will meet her later if she doesnt change her major
if you’re on campus enough you’ll see her
i am on campus all day, I have class from 9am to 2pm then from 5pm to 10:30pm
everyday
except weekends ofc
hopefully dawg
well its complicated, she was too pretty to be a math major, so I am not having too much high hopes tbh
need to join those mate, I have been just been stomped by university this first weeks everything is very different from pre university life
yea i hear you
you sort of drown in work and forget to do extracurricular stuff
i’m sure youll figure out what works for you
thanks dude, appreciate it
wdym? the classes I take?
I cant pick them, like, is a predefined course path
oh i see
year 5??
ye
its 1 year of foundations, and 5 years of bachelor, so 6 years
I do
oh alright that’s good then
well at least we go directly to phd if we finish the licenciatura
university like, prefers to make you a generalist
jack of all trades master of none, so to speak
how is university in where you live?
some courses are obviously locked behind prerequisites but it’s not bad at all
and sometimes you can just waive the prerequisites by emailing the professor and demonstrating you’re knowledgeable enough
crazy
very lenient
well I am not even mad brother, I get to study for free, and life is good, uni is filled with cute chicks
maybe its a little bit longer than usual
and like, courses are locked with prerequisites
🗣️
i mean they probably have your interests in mind either way
you could always learn something on your own if it’s that important to you to learn it
well there is a lot of optional courses you can take, but thats in the later years
because in the first years is everything foundational
you think so?
yea the structure they have has probably been tested for years
I am liking my Algebra I class dude, but Analysis 1 sucks ass, i dont like it
professors usually know what they’re talking about/doing
well some parts of math are just a chore
they have changed the analysis 1 course to make it less proofy
and more of like, multivariable calc
you need to know it to be able to learn more interesting things
because every science makor was taking it
hmm
fair dude
they don’t have something separate for math majors?
no, math majors need to take analysis 1 to then take analysis 2 to then take advanced calculus and real analysis
and then you can take advanced analysis I guess
my favorite
its a class that is shared with other majors
that is why every classroom has like 400 students
this will probably change in later semesters
the first few courses you take inevitably have people from all over
like my first semester had a course with every kind of engineering student, physics majors, math majors, applied math, economics, chemistry you name it
computer science
everyone
engineering 😭
yeah I gotchu
our faculty is like science faculty so I havent seen any engineers from like, pre university classes
but in the other hand, yes, chem majors, physics, cs and data science majors
you from america?
yea new york
i think I kind of prefer the approach america takes, where you can graduate cum laude, like honors, so to speak
and take honor classes and shit
with honor level students
yea it’s nice to go at a faster pace and be with like minded students
that way, is more liberal, but at the same time you can do what you want
the big apple
in the advanced classes you can tell all the people are total nerds who love math
do it all day
crazy dude, hopefully that shit happens to me, unless I get lost halfway through...
I appreciate it hard brother
no worries
will close this, I need to wake up tomorrow early asfk because of gymrat schedule, ty for the convo
you’re welcome have a nice night
.solved
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One moment, please.
convert cos in terms of sine of the half angle
and then substitute x=0
@molten bay
Q's in hindi, not used to that. U typed continuity, so i thought u were asking for that...... but nvm..... sorry again..... my bad.
Alpha is smaller than zero is impossible
for that would give a constant/zero form
that option can be eliminated
now checking the other three.......
=0 is not possible
for that would give 0^0=1
it would break the continuity
so alpha is greater than zero
is your answer
@molten bay
@molten bay Has your question been resolved?
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Can't catch up with the option C and B and D too
I'm done with half but it's multiple correct
newton's simplifications?
Idk
a^n - b^n is divisible by a - b
everything here is correct, which is good.
this is also alright..... okay now let me go ahead with the rest
there's a chance only these two options are right, so ill assume the other two are wrong and try to prove them as such. if im wrong, then you know that i am, and u may pick that option too
A,B and C are right
okay, so let's prove C is correct
i guess D was incorrect and u proved it using the exact same thing u did for A
btw..... did u get B?
Nope
No
I hadn't proven D
actually...... there are two ways to do this
i see the JEE advanced label..... so then binet's formula is out of question
and the other is what you're doing
ill send a picture, one moment.
@urban needle Has your question been resolved?
Oh great wait
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Can anyone please help me do this
I assumed D, B,A to be going downwards and C to be going upwards
And got A(d) =(A(a) +A(b))/2
And -A(c) =2A(b) +2A(a)
And from the rest of info given in question i got a(c) =-20/3 which corresponds to v=-20m/s at t=3 but in answer key it shows -57m/s
Can anyone please help me understand what I did wrong and how to do this question
Can someone pls help I have to submit my hw by tomr
<@&286206848099549185>
@gusty sky Has your question been resolved?
Bruh this is mathematics help not physics
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I'm kind of lost
I first thought this is a conditional probabilty probelm
so P(W|A)= P(W \cap A)/P(A)
but that doesn't work
so baye's theorm was my next idea
but for that I need P(A|W)
oh
P(A|W)=0.6
is it not
it is
$P(W|A) = \frac{ P(A|W) \cdot P(W)}{P(A)}$
wai
$P(A) = \frac{0.6 \cdot 0.9}{0.7}$?
wai
how did you get P(W)
P(W) = P(W|A)+ P(W|A^C)
P(W)=P(W|A)P(A) + P(W|A^C)P(A^C)
oh right
so with that change this would be fine?
yea you can solve for P(A)
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im not sure how to do this
whats the definition of odd or even functions ?
i dont know
fine ima write it out
i think its talkibg about the degree of the polynomial
oh well its kinda related to it yeah
and the diffrent shapes of graphs can be seen by the degree is it not?
fine but the degree of the polynomial isn't all
not rigorous but whatever
even: f(x)=f(-x)
odd: -f(x) = f(-x)
for all x in domain yeah
but how do i use that
Graphically, an odd function would be symmetric about origin and an even function would be symmetric about y axis, and their domains behave same
yep
ok
compute f(-x) and -f(x) and see if there are equal or if f(-x) = f(x)
if there nothing its neither
So you just need to check, which one of the graphs
- are symmetric wrt origin
- are symmetric wrt y axis
- none of the above
so i just put the same function equal to itself
yeah you’re right but be careful this technique only works if the domain is symmetrical to 0
well ofc, else f(-x) is a no sense and the question wouldn't be one
this admit a coherant domain
for each function f, you compute f(-x) and -f(x)
and see if there is one of the two equality that is true
if no equality stands, its neither
as a precision, the only function that is even and odd at the same time is the x : x -> 0 function
So far so good
and third one i got odd
yep indeed
4th i got nothing
why so
Where is the 4th I only see 3 in the pin
(the graph)
Oh my bad
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I wanted a hint
my first idea was to show that such a group always has an even number of elements
but that seems very hard to prove
Like I get $(n-1)^2 = 1mod(n)$ is probably the desired idea
wai
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Can you translate?
graph the intersection curve of the following surfaces
@tidal turret Has your question been resolved?
can I get some help?
I can try to help
hello
hi
i just joined
welcome to mathcord
yeah, this is an occupied channel
Unless you wanna help renato
yes please help me universe
what kind of objects are we dealing with?
i) first is a circle? and then what?
but a circle in r3 is a circular cylinder
a pringle
say what?
but we dont have that here
in spanish this quadric surface is called silla de montar
silla de monster
a saddle
yea
if you put a circle on it you get a pringle
,w plot z=x^2/4+y^2/9
i am so smart ong
guys no wolfram dude
,wolf plot x^2/4-y^2/9
guys, no wolfram allowed
there you go, pringle
guys no wolfram
z=xy you can figure some traces for y=x, z=0, z=1
then what?
So it means you already know the shapes
do you have to draw it in 3d or 2d
well, I know the one of the circle
the easiest is to just draw the circle and then draw the contour lines
we are mathematicians, not artists (although i would actually say a mathematician is an artist in another sense
)
or just work in cylindrical coordinates, no need to know what z=xy looks like in full
lol
x=2cos(theta), y=2sin(theta), then find the correct z for each theta using z=xy
i wanted a challenge
ok mate
no but I think the exercise wanted us to use traces and level curves
then 2d is fine
annyways, what traces should I try for z = xy
z=xy you can figure some traces for y=x, z=0, z=1
then we get z = x^2, z = 0, xy = 1
how will the graph of xy = 1 look like?
in the xy plane?
Haven't you been taught it in precalculus?

oh, you mean y = 1/x
isnt this an homographic function?
like we have some horizontal asymptotes at x -> 0
@tidal turret Has your question been resolved?
it would be if it was x^2+y^2 =< 4 but we have equality, so it's the boundary
the circle in r3 is a circular cylinder because z is free btw!
yea
wait, this are the traces of z = xy
some
umm I see
i wanted to show how it would kinda-ish look like
how did you graphed the z = xy surface out of the y = x and y = 1/x traces
what would be the intersection then?
I didn't quite draw the actual surface but traces of them
what about the intersection between the circular cylinder and the z = xy?
more less what will that be?
roughly speaking ?
is tricky drawing this just out of the traces themselves, like pulling out the graph of the quadric surfaces in r3 without looking at desmos or ggb
I see red and blue are traces of z = xy when z = 0 and when z = 1
the boundary curve of a pringle
If you moved the line x or mathematically, you have x-c
the parabola traces go down
wait a second dude, how did you found a trace y = x when z = xy, did you set z = 0 or z = 1 or what?
because I am not finding it, if you do z = 0 then y = -x
also you are drawing the trace y = x at a height z = 0 so I thought thats what you mean but then y = -x
In the plane y=x you get z=x²
if we move that plane back or forward the parabola moves diagonally and descends as well
For y=x-1 (in that plane) we get z=x(x-1), it intersects with y=x-1 at points (1,0) and (0,-1)
wdym boundary?
this is how you could do it in 2D you would have to denote the z levels
also, nice drawing, is just that,the green should be living inside the plane y = x
the red curve is called boundary
though I guess, is hard to draw by hand such that it looks like a pringle
because we have x^2+y^2 = 4 not x^2+y^2 =< 4
i would say, only thing I dont understand is the arbitrary decisionship of using the y = x trace
quite literally a saddle
but since its not a surface we cannot say its a pringle
its just the intersection between the surfaces
yes
I appreciate it
that is called boundary
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I'd like to continue with this problem I had yesterday night
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cx²+bx+a
cx²>0, a is fixed term
all depends on bx
max will be when bx is max → at 10b when b>0, and at -10b when b<0
i gave up and looked at the mark scheme
ill be quite honest i dont really understand it myself
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I need help proving forwards implication
and unfortunately there's no specification that V is finite dimensional so I cannot just specify some basis of V
Anyways
Suppose null S = null T, then dim null S = dim null T so dim range S = dim range T
That's about all I have rn
Maybe we could specify bases of both ranges of S and T
@hybrid crow Has your question been resolved?
maybe something with the first isomorphism theorem
since $W \cong V/ \ker(S) = V/ \ker(T) \cong W$
ExpertSqueeSQUEE
That wasnt yet introduced
yeah I guessed so
it doesn't even work what I said xD
try to define E in terms of the image of a basis
Yeah i thought about that
did it work?
Not for me
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Let me just clean up that notation rq…
𝙸𝚗𝚏𝚒𝚗𝚒𝚞𝚖³
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
oops sorry
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hey can someone please help with this illustration
how does the equation at the last step become 0
sorry, if this is too basic but i just started binomial theoram chapter
the identity used is nC0 + nC1 + ... + nCn = 2^n for all n
a way to justify this is "number of ways to gather anything from a group" is 2^n and also would be nC0, nC1, nC2, ..., nCn depending on how many things you gathered
but arent the odd terms in negative?
oh they are, I dont know how I didnt see that
you can also do binomial theorem on (1+1)^n
then do binomial theorem on (1 - 1)^n or something idk
wait so then this terms becomes 2^(n-1) -2^(n-1) which then cancels out right ?
few things up with that,
first, if we were using +s instead of -s, itd be 2 * 2^(n - 1) - 2^n instead
second, I mentioned the wrong identity here
thats nC0 + nC1 + nC2 + ... + nCn which is all +s
nC0 - nC1 + nC2 - ... with alternating signs is a different identity
conveniently nC0 - nC1 + nC2 - ... = 0 regardless of n
you can prove this by using binomial theorem on 0 = (1 + -1)^n
okk then here odd terms become -ve and even terms become positive and that is =0
yea, regardless of n
for example 4C0 - 4C1 + 4C2 - 4C3 + 4C4 = 0
since 0 = (1 + -1)^4 =(use binomial theorem)= 4C0 - 4C1 + 4C2 - 4C3 + 4C4
okk i got it thank you very much for your help
np
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No.3
I don't understand why showing h = af + bg has the period of p necessarily leads to "all functions of period p form a vector space"
I thought that all functions of the period p form a vector space if every function of period p can be written as linear combination of f and g?
a (nonempty) set is a vector space if any linear combination of elements in that set is again in the set
so if f and g are in that set, then af+bg needs to be again in that set
as it is a linear combination of some elements in the set
what you are thinking of is that f,g are a basis/generating set of that vector space. thats a different condition (and not true here)
So what I thought can be phrased as "functions of periodic p is a vector space" which is different from the book which says "functions of period p form a vector space"?
the set of functions with period p is/forms a vector space
usually "set of" is omitted
but doesnt change much
Yeah i guess it's pointless like saying to find a basis for any possible functions f(x)
Anyway this is pretty much solved
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Oh and ty
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hey, I don't get what they have done in this solution can someone please help
$\binom{n}{k}$ is the coefficient of $x^k$ in $(1+x)^n$, agree?
Ann
fine
okk nvm $\binom{n}{k}$ is the same as C_k right ?
Lulu
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$\binom{n}{k} = {}^nC_k$
Ann
it is still n choose k but way less cringe
dw write in whatever way ur comfortable with i just had no clue about this notation until now
anyway then they viewed (1+x)^(2n) as [(1+x)^2]^n
how did they transend from the 1st to the 2nd step ?
ohh and then we just get a series by doing this in every term
thank you very much i got it
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hi
hi
hi
can someone tell me why my steps r wrong
the other one is from the textbook answer sheet
the point r collinear
collineeer
however u spell it
The -r^2 + 6r + 5
it should be -r^2 +6r -5
oh wait
nvm
you forgot the integer rules
nuhh i mean likeee
i know
ahhhh ok this is the answer i wanted lol
r=1 or -5
interger rule
but it should be 1 and 5
whatstht
huh
then r = 1,5
which part issit
@hollow canyon Has your question been resolved?
Modulus over an algebraic expression refers to the positive value of the whole expression, not its individual terms
ahhh
For example |x²-2x+1|=x²-2x+1
Not x²+2x+1
show wat you did , and why you did , we can show where you went wrong
does is equals to x²-2x+1
Nope
no it equals to
|x^2+2x-1|
uhuhhh
ohhhh
sooo
ok idk how to say it
but basically positive turns negative and negative turns positive?
if its an expression
See |x²-2x+1| means that the whole expression needs to be positive, not each terms(as in x²,2x,1)
The whole expression (-x²-2x+1) could be written as -(x²+2x-1)
But putting a modulus over it,gives u the positive value the negattive sign gets removed, so u get x²+2x-1
ahh ok i think i got it alreasdy
thank u victim
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urgrhgrwiph
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I thought the points were -1/2, -2, -1
But it became differentiable at -2. Why?
Factor that quadratic
|| X = -2 is an even times repeating root.|| do what @shell wigeon told you to do so, it helps
(x+2)(x-1)
Right, and at -2, what is x-1?
-3?
So |x^2+x-2| becomes...?
0
Ok fair... not what I meant
Non differentiable
Which term is a problem at -2
?
Of f(x), which term becomes a problem for differentiability at x=-2?
|x+2| and |(x-1)(x+2)|
Ok but it's not just |x+2|, it's -3|x+2|
And |(x-1)(x+2)| = |(x-1)| |(x+2)|, right?
Yeah
And at -2, |x-1| = ?
3
Do you see where this is going?
The terms will cancel out?
Exactly
Perhaps a better way to view it is to factorize the terms
(|x-1| - 3) |x+2|
Around -2, you can get rid of the abs:
(-x+1 - 3) |x+2|
So the other terms becomes 0 and makes it differentiable??
Well, the true justification is to take the limit of the derivative on both sides
Thanks
Or you can see that -(x+2)|x+2| is a quadratic on either side of -2
It's a quadratic going up on the left, and the same quadratic going down on the right, but at -2 it's derivative is 0, just like the derivative of x^2 at 0 is 0
(all this is intuition, the justification needs a bit more rigor, but I'm sure you can do that)
Yeah
Thanks again
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someone help me with this please
a or b?
both lowkey
ok
can we start at a
...
i mean i would need to see pictures of your work anyway so... this is gonna make things difficult unfortunately
try using paint
whats paint
are you a windows user
if you are, i'm referring to MS Paint
im a mac
no, the square's side is not 1/4.
Do u know the formula of finding diagonals
1 meter is the diameter of the circular base; it appears as the diagonal of the square.
i don’t think so no
Or u could use pythagoras to find ot if u dont know that is
ohh
does either of y'all know such a thing as the pythagorean theorem
yes
ohh yeah
but u can also do the square root instead of c^2
you can write it as c = sqrt(a^2 + b^2)
in any case, y'all should know the ratio of a square's diagonal and side length
this ratio is sqrt(2).
OK
ok so um
soo
how do we use pythag on that
okayy
your hypotenuse is equal to 1
