#help-23
1 messages · Page 258 of 1
Yes
how good is ur vectors?
Ehm took me like 10 tries to draw what Cnidarian posted
so not so good but i kinda get how they work in this scenario
right
down
Yes think so
now how good is ur trigo?
Its Sin 45 and Cos 45
which is which?
280 N
.7 is sin 45
I mean 280 x sin 45 = roughly 198
so thats ur answer
yes 198 N
thats the answer for 1
Damm so horizontal is just cos 45. ok how about the weight?
yes so horizontal component also stays same as cos45=sin45
now coming to weight
they gave u mass as 50kg
now listen here
when u stand on a weighing machine what do u think it measures?
my mass
no
newtons
it measures ur weight
50 kg x 10 right ?
weight is a force
yes
So 500 N
the force
ur mass multiplied by gravity
yes
do we remove 280 since we are pushing?
but it might change if ur book took g = 9.8
hmm
one sec
no
if they ask apparent weight then u remove
no in this case u actually add the vertical component force
as weight and force r same direction
oh wait its 50 x 9.8 not 10
yes
490 Newtons is the weight
@barren bronze did u get this tho?
yes
no not really
last one?
the weight acts downwards ryt
yes
no first i gotta clear this concept
and a component of the force also acts down right?
the 280 newtons force
197 N?
So 197+490 = 687
yes
so normal force must be 687
that is the total force on the grounf
YES
that is normal force
alr now coming to the last one
do u know how friction works?
its opposite to the pushing force
uhh
no
dont think of it like that
friction is always opposing motion
so if not for friction
normal which direction would this body move?
just forward
now using this tell me which direction will friction be
Backward
not for this question no
theres this thing coeffecient of friction which is notioned with mu( the sign)
friction is always equal to mu multiplied by normal force
yeah in this case its mu d
whats d?
dynamic friction
But we dont have mu?
that is what they asked us to find
now listen here
the crucial word in the question is
constant velocity
what does that mean?
Same speed
Yes
only then its possible
so we have a condition that acceleration is zero
doesnt that mean net force is also zero?
but net force cent be zero if its still moving right?
y not?
Idk
if theres force means its accelerating
means speed is changing
but thats not the case
net force acting on the body is zero
becuz speed is constan
we know the friction force?
when we equate acceleration to zero we get it
as acceleration is zero
force is zero
as f = ma
then u get this equation
fh - (mu d ) * N = 0
we know fh
we know normal
Ya 198
198/688
fh = ( mu d ) * N
fh/N
YES
did u understand the process?
ya once i had the formula
alr thats good
so i draw the free body diagram first?
yes
split everything into x and y components
and then find normal and based on question react
Ya makes sense i take it step by step
which direction is fh and fv?
yes
Fh is right and Fv is down
well u got it but u gotta put arrows on fbd or u get confused
Aight imma have to go but yeah it makes more sense now imma have to practise more though
alr
glad i can be of help
clearing those concepts is imp once they clear the chapter gets easy
so ye i had to be patient
anytime
u too
@barren bronze do close the channel
.close
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how can i graph a complex number in a 3d euclidian space
by myself
You can graph complex numbers in desmos?
what exactly do you mean
if you have a function $f: \bC \to \bC$ then you can't plot it in 3d regularly
artemetra
you usually plot, for example, the absolute value of the result, which makes it a $\bC \to \bR$ function
artemetra
or the argument
but to plot a C → C function you'd need 4 dimensions
two for input and two for output
so two real axes and an imaginary axis
exciting
for the 3d
yes, correct
what are your sources for this information?
@dire storm Has your question been resolved?
@main mural
for what information exactly
i would need 4 dimensions to graph a complex function
is this common knowledge when studying complex analysis
sorta
you need two dimensions to represent 1 complex number
so a map from one complex number to another needs to be 2+2=4 dimensions
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What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
I have completed the problem and don't need help anymore. Thank you.
Use . close
@primal crescent Has your question been resolved?
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@primal crescent Can you plug 2 and/or 10 into f(x)?
x=2 is zero and x=10 is Remove discontinuty
type just ".close"
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( Law of Sines and Cosines ) - Trig
Does anyone know where to start for this problem?
Yes both sides and angles that are missing
Okay well right off the bat we don't need any trig to find angle A right
yes
exactly
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Don't know how to begin
do you know the formula for a tangent line for normal curves?
y-f(x1) = f'(x1)(x-x1)
not quite sure
but isn't it doing substitution?
idk what to substitute for them though
x=r * cos(theta)
y=r * sin(theta)
yea, it'll just be cos(2theta) * cos(theta)
lemme write this down rq
wait
i'm not understanding properly
so what exactly are we exchanging to put in cos(theta)?
we aren’t really
think about a right triangle
r is the hypotenuse
if we want the x coordinate of r, we can multiply it by cos theta
since cos theta is defined as adjacent(x-value)/hypotenuse
multiplying by r will just give the x value
@upbeat ginkgo Has your question been resolved?
sorry
got distracted with something
that's ok
x equals, not r equals
my bad dawg
no, now that we have x and y, we can find dy/dx
wait what
if x = r cos(theta)
and y = r sin(theta)
we can differentiate with respect to theta
and get dx/dtheta and dy/dtheta
we can then divide dy/dtheta by dx/dtheta
to get dy/dx
and is r considered a constant when differentiating?
is what?
no, since r is defined in terms of theta
so we can sub in the definition of r from the question
and then we can differentiate
I think it's clicking
let me write it all out and post it here
so that you can check if i'm getting it
@sleek plank
like this?
yep pretty much
then you divide dy by dx
and plug in the designated theta value from the problem
which is believe is pi/6
how about the 1/2?
i believe the 1/2 is the r-value
i don’t know why the ordered pair was ordered that way, with r first and then theta, but it works out mathematically so
alr, gimme a sec
cause I gotta show my work for this and it has to make sense to be correct
thanks for your patience
np man
@sleek plank looks good?
idk why the highlighter blocks the slope
but it's sqrt3/7
LOL
what the hell
oh
bruh
hmm
makes sense that its negative just by looking at the graph
now what have I done wrong?
give me a second to look at it
ok, thanks!
oh wait wolfram didnt intepret the problem as polar
your answer should be correct
i did it myself and got the same thing
yw!
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how do you find concavity using derivatives I’m having trouble testing and knowing what intervals to use
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hello can someone help me with this? it's a weighing and scale problem
A+B+C=D+D+D+D+D
D+D+A=B+B+C
A+A=?
A= 5D-B-C
A=2B+C-2D
A+A=3D+B
E is an option
omg thank u I was confused when I made the replacement 😢
you're just new at these operation
just hone your skill and you will be fine
take more practice
thank u buddy, i will
no problem
.close
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What are consecutive sides?
Apparently they’re congruent???
huh
@frail beacon Has your question been resolved?
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can someone help? i have tried so many times and always get the same answer which is wrong
I figured it out
.close
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Help
maybe try proving the contrapositive
if X is not compact, then either it is not closed or it is not bounded
in each of those two situations, try to construct a continuous function on X that is not bounded
The contrapositive is true for subsets of "R"
should also be true for R^2 i believe
@lean otter Has your question been resolved?
@lean otter Has your question been resolved?
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I don't quite understnad what these problems are asking for
I'm expecting to see this type of problem on my exam, so I want to properly understand how to do it
I am not sure about the absolute sign, but I think they are asking for that term to be less than 10^-6
Hint: ln(a^b) = bln(a)
wdym?
like the term of n to be less than 10^-6?
$\left(\frac{6}{7}\right)^n < 10^{-6}$
#damiforthepresident
and for $n > 0$, we can see that $\left(\frac{6}{7}\right)^n$ is decreasing
#damiforthepresident
cause the denominator is always bigger than the numerator right?
do we solve this for n?
yeah
oh
alr
gimme a sec
i'm gonna try to do it and if you could possibly check my work, that'd be great
NOW I see what you meant by this
and remember to check the sign
you will see
yeah that is pretty much it
mhm
now I calculate the number
and will the greater than sign affect my answer?
cause it's asking for N, not n
so it's tripping me up now
so you got n > something and your N is the minimum n that is the whole number
n > 89.6234163446
ok.
so then it'd be 89?
no
because n must be at least that much
but N also satisfy the condition
I mean, if not then I can pick negative infinity and I will be fine
ok
let me make sure i'm understanding
this confuses me, so bare with me
89.6234163446 is the minimum amount you need
and N is the minimum whole number that you need
so then it'd be 90?
yes
ah!
ok
so if the number came to be 88.1234
the minimum whole number would be 89
yes
no problem
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Hi, I was struggling to understand how to do this question as there is limited information and the working out provided doesn't make sense.
essentially solving a system of equations here
ik variance, idk binomial dist
how do you do that with probability?
you have to use the formula for mean and variance of a binomial distribution
do you know them?
Okay, what do you know about variance
Recall that the mean of a binomial random variable is μ=np where n is the number of trials and p is the probability of a given trial’s success. Furthermore var(X)=np(1-p)=μ(1-p). Since μ=12 and var(X)=3, the argument from here is simply arithmetic
I’ll leave the answer below with a spoiler, but I implore you to try and solve the question from here before revealing the answer. If there’s anymore confusion, feel free to ping me :)
||p=3/4||
@lean otter Has your question been resolved?
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Find all the solutions $u(x,y)$ to the partial differential equation \$\frac{\partial^2 u}{\partial x^2}+\frac{\partial^2 u}{\partial y^2} = x^2+y^2$ which depends of $r=\sqrt{x^2+y^2}$, i.e is of the form $u(x,y)=f(r)$.
Merineth
Are there actual people who understand these type of questions from the book and know how to solve them?
How do i actually learn when i'm unable to solve the questions?
@junior smelt
'
@safe parrot Has your question been resolved?
i wish i died
haha, did you try to view $u(x,y)=f(\sqrt{x^2+y^2})$ and plug that into the equation?
NulledOutChicken
no, i have literally no idea what i'm supposed to do
haha
Like i can't even interpret the question right
Okay I just gave you a hint
Use that expression, just plug it in and try to simplyfy for now
The understanding usually comes AFTER you solved it
do you know what $\frac{\partial f}{\partial x}$ means?
NulledOutChicken
yes, the partial derivative of f wrt x
Do you know how to compute it?
Yes.
And do you also know how to use the chain rule?
When it comes to one variable, yes very. Multivariable i'm not sure
if it is a partial derivative, the chain rule works like with one variable
Ok but i dont understand the question that i'm given.\ \
It asks me to find all the solutions to: $\frac{\partial^2 u}{\partial x^2}+\frac{\partial^2 u}{\partial y^2} = x^2+y^2$, right?
Merineth
and it gives me a condition r?
Okay, you are thinking the wrong way around
The first thing you should think about is how to simplify the question
Try to use the info you have got
My first instinct would be to replace u(x,y) with its condition
- FInd all the solutions to the function u(x,y)
- add the condition r
Does this simplify it?
Try it
$u(x,y) = \frac{\partial^2 u}{\partial x^2}+\frac{\partial^2 u}{\partial y^2}=x^2+y^2$
Am i thinking correct?
Hmm
Merineth
you already have $u=f(r)$
NulledOutChicken
i dont know what u=f(r) means
Maybe start by just plugging that in first?
Lets start simple. Try to expand $\frac{\partial f(r)}{\partial x}$
NulledOutChicken
I have no idea what that means'
Like i dont think you understand, i do not know what to do
i literally dont understand the question
This isn't simple to me
How do i read the question such that i understand what i need to do
i need to be able to solve these questions on my own
and that requires me to understand
Okay they ask you to find this derivative $\frac{\partial f(\sqrt(x^2+y^2)}{\partial x}$
what they are asking for
NulledOutChicken
and how do you know this?
Thats what it basically boils down to
Why isn't that mentioned in the question?
Yeah but if i sit down on the exam, i'm supposed to understand this
I can't have someone add additional information that is neeeded
for me to even understand what they are asking for
And you will if you stop whining, man up and take that damn derivative
whining
i'm litearlly fucking suicidal
since
i dont understand
whjat i'm supposed to do
Try to answer that for now
And calm down men
Really chill
$\frac{1}{2\sqrt{x^2+y^2}}$
Merineth
haha okay lemme do it for you
$\partial_x f(\sqrt{x^2+y^2})= (\frac{x}{r})\partial_r f(r)$
NulledOutChicken
Okay I know a way to explain what they want from you
They basically wanna you to rewrite $\partial_x^2 f(r) +\partial_y^2 f(r) like \partial_r^2 g(r)$
NulledOutChicken
Not at all
The chain rule definetly does not work that way
Also, you used the absolute chain rule for partial derivaives
and you should expand partial x of f(r)
not the other way around
You should be using it like that
$\partial_x f(r)=(\partial_x r)\partial_r f(r)$
NulledOutChicken
Also, do not set everything equal to u, you already have u in the equation, use something more appropriate like g(x,y). I also think your approach si wrong, since you should definetly simplify the partial derivatives first
So your mission is to find anotehr expression for $\partial_x^2 f(\sqrt{x^2+y^2})$
NulledOutChicken
you think you can do that?
@safe parrot Has your question been resolved?
I'm very sorry but i just dont understand what you mean
@safe parrot Has your question been resolved?
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if given
$$S = {x \in \mathbf{Q} | x} S \subset \mathbf{R}$$
use \{
sorry
Mephisto
that's better
does that mean that Q are the accumulation points of this set?
and that there is no interior because of the fact that between each rational number, there is a irrational one?
I'm also assuming IR are the boundry points of S, because boundry points don't have to be a part of the set
meaning it's not a closed set, but also not an open one?
is this possible?
What exactly is the set S you're defining? The formatting makes it hard to understand what you mean.
I was trying to use the notation from my book, would be wayy easier to just say all rational numbers as a subset of all irrational ones
so just a set $\mathbb{Q} \subset \mathbb{R}$
So just a subset of Q or Q itself?
Mephisto
that's better
the set of all rational numbers as a subset of all real numbers
it has to be specified, otherwise if we consider all rational numbers independent of all real numbers, the set of boundry points would be an empty set
Yeah I see what you mean, it wasn't exactly clear. So Q inside Euclidean space.
Indeed, the interior of that subset is empty.
Its boundary is just R, which includes irrationals, thus it's not closed.
So it's neither closed nor open.
oh alright, so it is possible?
Yes, sets are not doors, they can be open and closed simultaneuously and neither as well.
it just seemed like a contradiction at first, but it might be because of the words used to define the terms
It's because closed sets are not defined as sets that are not open. Rather, they are sets whose complement is open.
ohhh okay
so the complement of Q sub R, would be R\Q which is both closed and open?
can you clarify?
No. If Q is neither open nor closed, then its complement is also neither open nor closed.
so if I'm following correctly, an interior is a property of any subset? is that what you mean?
ohhh okay I see it now
Q sub R, is not closed and not open its complement must be, not open because Q is not closed, and not closed because Q is not open
what were you thinking of?
alr guys, thanks for your time, I think I got it, closing this one
If X is not open, then R\X is not closed
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The task is to Using a double integral, calculate the area of the region D bounded by curves.
I don't understand how to get the upper limit for x
the curve for the upper limit is y=lnx
how do i get x?
In case my drawing isn't readable
like that?
<@&286206848099549185>
I got this, but I don't think it's right
Yeah that looks good
oh nvm
I had the answer given like this
why would you do that
lol
my teacher is trolling me
.close
Closed by @worthy frost
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hey i have an uncanny question
how would i graph this graph in desmos?
im trying to make a semi realistic sailing game
and im struggling with the math
i have already caluculated the boats angle to the wind and the wind speed
or get the formula for a graph like this
thats the main issuelol
or really
whhat would a formula for this be?
what does that eben look like
is it poossible?
<@&286206848099549185>
could i acomplish it with a gausian function?
This is definitely polar
@narrow venture Has your question been resolved?
any chance you can make it for me?
i havent covered it in school yet
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How do I do (iii)? Tried multiplying sum of square and sum of cube up but to no avail.
Especially after multiplying sum of square and sum of cube up I don't know what to do with the shitload of strange variable multiplies
would consider Newton's Sums here
Ok so it is something my lecturer haven't taught yet
I'll skip it for now
Thanks!
.close
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okay so
you know the properties of exponentiaton?
a^2 * a^3 = a^2+3
alright, so using the same property
we can say
srory
there
okay, so using that
() on exponent
we can do x^2 * x^(-2) = x^(2-2) = x^0 = 1
therefore x^2 must be multiplying 1/x^2
for it to be 0
1*
in general, negative exponents indicate that the the expression is inverted
and the reason is what I just mentioned
no problem
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Question:
How do I "expand" values as they approach 1? Red line is the input, blue line is the desired output. The the value of the blue curve at 1 would ideally be controllable with a variable, I don't want it to necessarily approach infinite at 1.
Bonus:
Could this be done in a way where the "sharpness" of the curve can be controlled with another variable? See the light blue lines.
What I tried:
The answer ChatGPT gave me, e^(k*(x-1)), seemed to do the opposite (affecting only values below 1), and I couldn't quite figure out how to flip it around. Also, it doesn't give me control over the curve tightness. I think it might just have been too difficult for me to explain the problem to it.
Context:
I'm writing a shader for a video game where this came up. Normally I can google my way out of math problems like this, but I just can't wrap my head around this one.
Any help or just hints would be appreciated.
I'm writing a shader. Looked up graphwars, and it looks like fun if you're not as bad as me with math.
nah its just some graph you need to memorize
like the abs(x+5)-abs(x-2) to shift the graph
for 1
dont you do like x+e^(x-k)
k is the adjustable value
itll look smth like this
e^(k*(x-1)) + x
actually that seems right
-1 is how you adjust where the curve "spikes"
That looks right, let me give that a try real quick
and k is the amount you want it to increase before it goes to infinity
add +x to that
okay here we go
g is the initial gradient
k is how fast you want the graph to "spike"
Maybe I'm just implementing it wrong. I'm still getting the other way around, it's lifting the lowest values instead of the heighest.
and -1 is the position of where you want it to spike
wdym by this?
try this
play around with the values until you get your desired result
Does this look right? Maybe I'm making a mistake when converting things into nodes. I'll try writing it out as a script instead
ooh Desmos is very helpful. Thanks for the tip.
@willow nexus Has your question been resolved?
I haven't figured it out yet, but I'm going to close the room while I fiddle. @austere brook Thank you
.close
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Could someone help out? I proved the first part, but what does it mean by the second part?
Hence find an expression for I(n) in terms of n for n> 0
It means you need to express I_n in explicit forms of n, instead of I_{n-1}
so i'm assuming that'd mean find a way to integrate the I(n-1) term
so it's in terms of N throughout and not recursive...?
would you hve any idea how I could go about doing that?
@plucky swan Has your question been resolved?
You have a recursive formula about In
So start from I0
How do you get I1?
You do 3/5 I0
How do you get I2
You do 6/8I1
Which is 18/40*I0
And so on
Find a way to generalize this
Okay
Would I form a series of some kind?
I haven't done anything like this before, would you mind sharing the answer
@obsidian oracle
factorials!
Still, it doesn't end up being true for n = 0 with factiorials
(3n! / (3n! + 2)) * 1/2
Still only true for n > 1
I really have no clue where to go I've tried everything I know
And I need to know how to do this
I tried to work on this but can't find the answer. If you somehow get the answer without the proving step, you can prove it by induction.
Could you show me how it could be proved via induction?
for example we know that $S_n=\sum_{i=1}^n i=\frac{n(n+1)}{2}$ and $S_n=S_{n-1}+n$
then we have $S_1=\frac{1(2)}2=1$, then assume that this hold for n=k, we can prove the case for n=k+1 by the recursive relation
$S_n=S_{k+1}= S_k+k+1= \frac{k(k+1)}2+k+1= \frac{k^2+3k+2}2= \frac{(k+1)(k+1+1)}2= \frac{n(n+1)}{2}$
Micni9
can you write your answer in terms of the product symbol?
normally I assume the answer need to be in closed form
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Would the proper way to read this integral be
The integral of x times sine( x) with respect to the derivative of x?
Or like the integral of x times the derivative of sine(x)?
neither
How would it be read then?
integral of
x times sin(x) (would be better described as the product of x and sin(x))
with respect to x
I dont need to specifically state that I’m using the derivative of sin(x)?
!rccw
Ugh
Ok so im integrating by parts with this one so im just splitting it into x and sinx dx
you want
dv = sin(x) dx
And that leaves me with v=-cos(x)
But how would u call out the problem it’s giving me without explicitly just writing the numbers down
Like if I had to call this out after seeing it what would I call it
My first thought was what I said earlier
So I’m still thinking
the initial problem itself was what i described earlier
Yeah
Just if I were to say this out loud what would I be saying
If it isn’t what I thought it was earlier
the initial problem itself?
was what i described earlier
But how would I be able to tell it’s sin(x)dx
wdym
Like what’s the indicator that it’s an integral or derived with respect to x
whether you have an integral sign
or derivative operator
What if it isn’t written though
wdym
Assume as if I’m writing this down as someone’s telling me
How would by word alone I break this down to write the question
integral of
x times sin(x) (would be better described as the product of x and sin(x))
with respect to x
THAT
if you understand the terminology
So with respect to x just means dx
that will give you precisely what you gave me
dx is referring to the increment
But what if for some reason I wanted the second derivative of x how does that change the wording?
d(what to integrate with respect to) at the end of the integral expression tells you what to integrate
Ahhh
if you wanted the second derivative of someothjing
But like here’s the work I used
It tells me to integrate x but then after u get like
that would literally be
second derivative of (that something)
add with respect to variable of choice if intentions are unclear
dv=sin(x)dx and just turn it all into v=-cos(x) when I derive it
you're getting integrals and derivatives mixed up
I’m integrating by parts
you get
v = -cos(x) when you integrate it
starting with
$$\dd{v} = \sin(x) \dd{x}$$
$\textbf{integrating}$ both sides:
$$\red{\int}\dd{v} =\red{\int} \sin(x) \dd{x}$$
gives
$$v = -\cos(x) \gray{+C}$$
(you don't care too much about the C there as you can just assign that somewhere else in the overall integral
ℝαμΩℕωⅤ
But what exactly happens between integrating it and the solution? Like how do you know what it integrates to
integration is the reverse of differentiation
knowing v differentiates to 1,
the antiderivative of 1 is v
knowing the derivative of cos(x) is -sin(x), derivative of -cos(x) will be sin(x)
the antiderivative of sin(x) is -cos(x)
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How do I do this ?
firstly: what does it mean for a matrix to be nilpotent
There exist a power raised to which the matrix becomes zero
e.g A^n=0. If there exist such a "n" the matrix is called nilpotent.
I'm trying to think of a good way to motive the next part of this proof
basically, we want to factor (I + A^n) into the product of (I+A) and another matrix
you can think of this as polynomials, if it makes it easier
Ok..
this factors into something like (I + A^n) = (I+A)(I-A+A^2-A^3... + (-1)^{n-1} A^{n-1}) and we get our inverse
maybe an easier way to see it: if B is invertible, then the determinant of B+A is det(B)+det(A)+det(A^-1 B)
here, we have det(I+A) = det(I)+det(A)+ det(IA) = 1 + 0 + 0 = 1
which means it's invertible
If we can get this part
Do we still need to do the determinant ?
Oh
no, but sometimes the determinant is easier and sometimes it's harder
note this isn't always true actually, nevermind
If A is nilpotent then A have a inverse. (That is the determinant is not zero)
if the determinant is zero it doesn't have an inverse
If A^n = 0 then detA = 0
this doesn't prove the thing we want it to
ooh wait I have a snappier proof
if (I+A) is non-invertible there is a nonzero v such that (I+A)v = 0
this means that v + Av = 0 or Av = -v
let's say that A^m = 0. On the one hand (A^m)v = (-1)^m v, but also (A^m)v = 0v = 0, so we have (-1)^m v = 0 i.e. v = 0
bam, no polynomials needed
Wait
(A^m)v = (-1)^m v (How?)
Av = -v
A(Av) = A(-v) = v
AAAv = Av = -v
etc
each application of A picks up a factor of -1
ok
Is this a theorem ?
Yeah, if a matrix isn't invertible it has nontrivial kernel
If a matrix is not invertible => the determinant is zero => kernel is non trivial
Makes sense
When you looked at the statement for the first time did you know that it is true ?
I think in this case you kinda just intuitively hope it’s true first
Since it’s easier to prove that it’s true than to prove it’s false
At least I think it is
If you really dont get anywhere with trying to prove its true, maybe then you can start doubting and try to prove that its false
Actually tbh if it was false, it may not be hard to prove that the determinant is 0 for example
Do you have anything to say @carmine knoll
It looked true yeah
Because of the polynomial thing
@lean otter Has your question been resolved?
@lean otter Has your question been resolved?
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greetings
if 2 cos 45degrees = 2 * pi/2 and sin 90degrees = pi/2, is 2 cos 45degrees = sin 90degrees?
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so i was looking at some cambridge interview questions. the first question was to figure out what sin(x)/x would look like. what is the thought process for trying to figure that out
what sin(x)/x would look like in a graph
Knowing its zeros, critical points, and limit at 0 would be useful
Also knowing its end behavior
idk man none were given
find them
none were stated idk what to tell you
yeah this would be really easy if they were stated
you're supposed to find them
using algebra/calculus
you can also think intuitively about what its end behaviour would look like at +/- infinity
then you aren't deserving of Cambridge if you don't even try to find basic information about a function
gotta get to work
i thought it was simpler than that i'm sorry😭 I don't know that math yet
i'd say think about it when x > 1 or x < -1, then it's basically just sin(x) but the amplitude keeps getting smaller and smaller as you move further and further from 0 in either direction.
when -1 < x < 1 ask yourself how is the amplitude changing?
what is happening at x = 0? obviously the function is undefined, can you find a limit?
consider if anything like even\odd function is relevant here
well either you're preparing for the test during the same year, or your knowledge is lackluster yeah
have you taken calculus yet \ are you familiar with limits?
if you haven't don't study uni entrance tests
no not at all I'm getting to that next year. I didn't know the question involved that
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that only makes sense when you're already very familiar with all the material
not necessarily to get a good idea of what the graph looks like, but it's much more likely you'd have the familiarity needed with functions and the important bits to look out when thinking of graphing and the behavior at x = 0
also surprised they'd only start calculus during the last year of HS
but agreed with what bezier said about focusing on that before entrance exams
maybe they're a freshman looking ahead!
2 years ahead?
it's been known to happen i guess if someone is planning for a specific school ahead of time
if they look 2 years but can't figure out it'd be beneficial to learn the material first idk what to say besides sorry for you
.reopen
✅
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can someone explain this one please?
Are you asking about the f•g notation or something else?
Also to answer the question you need to have other information about f and g
reallly?
that's all i am given
i am lost at what its asking
Does it assume f is a polynomial?
Is that the problem? Where does it say that
nothing in there says about inverses
how did you come up with that? is it the numbers?
g(-4) = -2
f(-2) = -4
wait nvm there are quite a few exceptions here
(fog)(14) isnt 14 tho
yea things like that rebuke my theory
is it possible that the problem is not complete?
i mean that's all im given but still
and I don't see a pattern
what if you assume that different inputs must lead to different outputs?
for example the topmost answer box cannot be 14, -4, or -2
if you make this assumption, youre assuming that f and g are "injective" which is a normal thing for functions to have
I have to fill it all out