#help-33
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Merineth
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can someone help me solve this i have already solved a. "Let F : R^4 → R^4 cyclically map the basis vectors e1F→ e4F→ e3F→ e2F→ e1.
(a) Derive F's mapping matrix A, such that F(x) = Ax. Show that A4 = I4 and that AT = A−1 = A3.
(b) Show that if λ^4 = 1, then λ is an eigenvalue of A with associated eigenvector (1, λ, λ^2, λ^4)T.
(c) Brilliant and diagonalize: Find a diagonal matrix D and an invertible P such that A = P DP ^−1
@urban bobcat Has your question been resolved?
Can I use the formula A*e = lambda *e?
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How would I approach this? I’ve already tried reversing the summation and converting it all to exponential functions but neither of those seem to lead anywhere
Looks like they multiplied the numerator and denominator by sin(x/2) and used the product to sum formula
Hmmm ill try that
I need to look at the product to sum formulas I guess because all I’ve been doing is converting to exponents, doing some algebra, and converting back lol
I’ll keep the channel open for now in case I fail miserably
Wait this is a telescoping series now
Thanks!!
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would anyone like to verify my work?
this is the original question
part b
I'm adding 2 vectors and using cosine and sine law to find the magnitude and bearing
I believe my cosine law is 100% correct, I just want someone to double check the sine law
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@lilac scaffold Has your question been resolved?
I think you used the wrong numbers for the sine law, it should always be the angle over the side directly opposite of it
wdym
which sin(B)/7 isn't
oh thats my bad
it should be sin(b)/2 right?
if you're trying to find that angle on the left yea
yeah exactly
cause when i find that interior angle, i can add the angle between the line a and 90 degrees
then subtract it by 90 degrees
and that would be the distance between 0 degrees and the dotted line
ykwim?
which should be 45.4
...if i got evertything right
I get 20 degrees, let me check it with sine law
ok
was this what you had?
i got the answer in a decimal
and no
the top part is 2sin133
which is the same as 2sin47 i believe but whatever
either way there should be that 2 in front
oh I have the wrong angle mb
uhh what numbers did you get for the sine law angle then the final answer?
the sine law angle was about 14.6
then considering theres 60 degrees above that, the final answer (the heading of the dotted line) should be 45.4
...i think
I guess it's the cosine law magnitude giving the discrepancy hmm
maybe a calculator typo?
ok yea you have to extend this square root over the whole thing to get 8.49
am I supposed to get 8.49?
oh wait
sorry thats also a mistake
its supposed to be over the whole thing
yea if you fix the square root it gets 8.49 and that'll fix everything
oh shit wait
cos133 is different than cos47
i originally used cos47 in my calculation
and theyre not the same at all
uh ohhh
okay gimme a couple minutes let me redo it
okay it says the interior angle is 9.9
that seems quite small..
thats possible though right?
like it doesnt seem unrealistic?
9.9 is right
probably because the side length 2 is so small
or like.. 179.9
yeah exactly
my drawing isnt quite to scale loll
okay i guess thats the end of it
just to check what do you get after 9.9? for the final angle bearing
oh 50.1 is off let me draw it
a+b-> is 8.5m/s [050.1 degrees]
wdym
yeah
but nono
hold on
oooh ya i even did that wrong
jeez
it should be 30 - 9.9 right?
right
i was doing 60-9.9 like from the top
the other way should've worked but there's a lot of minus signs to mess up
yup I confirm
👍 np
situations like these helps me understand how important it is to check eevery possible mistake
🙏
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Really can't think of much, tried substituting some variables in hope but got nowhere
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i tried using ptolemies but now im stuck
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You guys really hate geo
who doesnt
I personally don't know any geometry, so I couldn't help if I wanted to
not that I want to do geometry anyways lol
I suppose you should just be patient and wait for someone
or you can post in #geometry-and-trigonometry
me.
nvm i hate it
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can some help me show that these are equal by hand?
(1/3) k (k+1) (k+2) + (k+1) (k+2) = (1/3) (k+1) (k+2) (k+3)
I put it into the computer and it told me there are equal but i cant figure out how to do it by hand
~~Expand the left side
Expand the right side
You should get the same thing~~
Actually nvm. Take the left side and common factor (k + 1)(k + 2)
factored it out and got (1/3)(k+1)(k+2)(k+1)
im not sure where the k+3 is coming from
Watch out for that 1/3. You should have got:
(k + 1)(k + 2)(1/3 k + 1)
okay I see
If you then proceed to factor that 1/3 out, you will get the right side exactly
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anyone how to approach this problem?
well first find the "orthogonal complement of the column space of (1,1)"
which is a rather obtuse way of saying something much simpler in this case
right, how do I find an orthogonal complement of a vector
well in this case you're in 2 dimensional space
so what is the dimension of the orthogonal complement of a vector?
wait, vector orthogonal to [1,1] is either [-1,1] or [1,-1] right?
sure
yep
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the only limitation i see is like
its not an actual graph or whatever
what do they want??
limitations refer to domain and range of function
yeah lmao
yep
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Been studying for too long and officially braindead. I'm sure it's obvious, but I can't think.
Why would it be nonsensical or invalid to do:
P=P(1+r/e)^et
Yes, I know this is incorrect. I know that e represents continuous growth. I know I'm plugging e into the discrete compound interest formula. I'm just asking for clarification on specifically why we can't just say "e times over the course of a year," etc.
Like, if we were just some crazy bankers looking to have fun, and we just decided to get wonky and do interest with this formula (whenever the interest rate is supposed to be continuous), what would happen to the money?
,w eulers number
e is approximately 2.718
meaning you'd compound 2.718 times a year
which would work just like how youd compound 2 times a year
or 4 times a year
or 10 times a year
if u want to compound continuously, use A(t) = P*e^(rt)
Why do we raise e to the rate? Maybe I need to sleep lol
im sure theres some proof of continuous compounding out there somewhere
(1 + 1/x)^n as n to infty
Thanks folks, I'll take a look at that and maybe some proofs.
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I don’t know if I’m on the right track or if I did this correctly.
I’m so confused
Nope, I don’t think you’re on the right track
You’re not supposed to get x when solving for p
Idk how to approach the question
Oh that’s the division statement?
yep
I did that and then I rearranged to isolate for p
yes
Should I do the division statement for my long division or for the info in the question? I mean with -13 and stuff
Just set every unknown coefficient about Q as a b c d
Oh ok
Ping me when you’re still confused after trying
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where is (4)(24) coming from, since we are not given a function?
It’s a triangle!
base is 4, height is 24
why are we just ignoring the intgrals then?
like youre not integrating anything youre just using the forumla for the area
so youre using it in a more indirect way?
the thing is, there is a defined function you can take the integral over
It’s f(x) = 6x when 0 leq x leq 4, and f(x) = 24 when 4 leq x leq 8
if you wish, you may integrate that as you like
But you’ll see that you get the same result as just adding the areas of the triangle and rectangle components
that’s why it’s far quicker (and probably preferable) to just use formulas for the area of a rectangle and triangle
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why is 0^0 equal to one? if i use the same argument for 0/0 being indeterminant (approaching negative infinity, positive infinity, and zero), 0^x equals zero for all x values up to 0₊, and on the right it equals 1/0^x, which is also undefined. meanwhile, x^0 always equals 1. is there something i'm misunderstanding?
this is just one of those things
some will say its 1, some undefined, some 0, though usually either of the first two
saying its 1 is just from the definition that any number ^0 is 1
its context dependent
like i understand how it can be seen as indeterminate for calculus, but if we can just set 0^0 to be defined as 1 in some cases, why cant we do 0/0 = 1 because any number x/x = 1?
Because you’re dividing by 0
if x=0/0 then x*0=0, x could be anything for this to hold so x doesnt really have a defined value, thats perhaps an overly simplisitic look at it
@potent token Has your question been resolved?
if we define 0/0 to be 1 everything will break
0/0 is undefined
it's not really rigorous since im multiplying by ln(0) and just setting it to zero
that's the problem
im aware of that but if its a definition then it has to make sense somewhere
definitions are just things we accept as true
but i dont like that :(
0^0 is defined differently based on the context
sorry, thats just the way it is
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Which of these is a map/illustration (not sure what the correct term of it is in english) and why (not)?
z : IR → IR with z(x) = { ⌊x⌋ for x ≥ 5
−x + 9 for x ≤ 5}
w : IR → IR with w(x) = { 4x² for x ≥ 2
⌊9x − 3⌋ for x ≤ 2}
my approach is: both aren't maps because the in the definition area are values that are connected with values more than one time. If I put 5 in ⌊x⌋, I get 5. If I put 5 in −x + 9, I get 4. So 4 != 5
I agree, they're both not functions/maps because of the multivalued parts you said
and is this a function? f : IN → Z with f(x) = 3x/sin²(x)+4
I would say it is again not a function
uhh how does you class define IN because everything is fine besides x=0
oh IN is like {1.....100000+}
1,2,3,4,5
all natural numbers from 1
I thought that sin²(x) is (sin(x))² and then sin(x)
so 3x/sin(x)+4, when I put in 1 I get 3/0,017+4
3/4,017 = 0,74
and 0,74 is not a natural number
but maybe I'm wrong
oh right makes sense, not a valid function
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Find any horizontal or vertical tangents to:
@still temple Has your question been resolved?
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you can find the equations for x and y in terms of theta (x = r * cos(theta) and y = r * sin(theta))
then take the derivative of each and equate to 0
i know that already
the rest of the process
okay
if you start with x
you can multiply the expression for r by cos(theta)
so 3(1 - cos(theta))(cos(theta))
then you'll end up with an expression for x in terms of theta
and if you take the derivative with respect to theta
then equate that to zero
then you can solve for the angle at which the rate of change of x is zero
which would be a vertical tangent
then you can take the angle you get and substitute it back into the x = r * cos(theta)
and you should get an x = ___ line as your tangent
then you can do the same for y
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Can you please check if the proof is correct
Prove $(k,m)=1 \implies (m-k,m)= 1$\
Proof: Suppose $(m-k,m)=d \neq 1. \
d |(m-k)$ and $d|m
\implies d|m$ and $d|k$
but this contradicts (m,k)=1
Dubs
i think i should add little more on how d|(m-k) implies d|m and d|k
Improved version, please check
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Does this limit exist (as x approaches 0)?
yes
does it?
Because from both sides they approach 5
yup
but at x = 0 its -2
the actual value of he function doesnt matter
your question should be "why does this limit exist"
you just need to see what it approaches
Ohhh
so limit is different from equalling?
basically
is equalling a word
i meant equality
equalling ?
uh
Basically if there is a point which exists when the limit approaches some "x" then the limit exists
given that the LHL and RHL are the same
soo
the limit is not always the same as the value of the function at that point
yep
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how to do part f
in the numerator
do the prime factorization for each of those numbers
oh
the 8^-1
goes to the denominator
as a^-b = 1/a^b
so the Dr is (6^2x*8)
the 6 is written ad 2*3
and the 8 as 2^3
so the Denominator is (2*3)^2x X2^3
using the laws of exponents it can be finally written as
2^x*3^(1-x)
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I need help doing calculus
Could someone provide me basic calculus worksheets that will help me understand because I am learning.
are you in calc 1?
@dire pulsar Has your question been resolved?
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In an alien world, there’s a peculiar plant known as the Starlight Creeper. This plant has a unique growth pattern; from each of its stems, three new stems emerge every year. This process starts with a single stem and continues for 10 years. Determine the total number of stems that the Starlight Creeper will have at the end of the 10th year, including the original stem.
So I understand that in the beginning theres one stem, then 1+3, then 1+3+(12), so basically its f(n) = f(n-1) + f(n-1)*3 right where f(0) = 1
is that correct?
in any case, how do I proceed?
i asked chat gpt and it formed a geometric series which I kind of understand where it comes from but Im hoping for a detailed explanation for an understanding so that I can solve similar questions
yes
In the next year, we get 3 stems from each stem
so we get 12
so we have 16
in the third year,
we have 3 stems growing from one and we have 16 stems
so we get 48 stems
Can you see a pattern?
but 16 right cause the one in the beginning
ah yes my bad
so the sequence is 1 + 3 + 12 + 48 and so on
ah
at the origin of year, we have 1 stem
at the end of one year, we have 4
at the end of second year, we have 16
at the end of third year we, have 48
also, why are you adding these
ah yes
is it obvious now
there’s an easier way to do this
what the sequence is is an arithmetic sequence
this is the formula for it
my bad, it asked the total number of stems at the end of 10th year, i got confused and I was already adding them in the sequence
a sub n = the number term you are trying to find
how is it an arithmetic series
a sub 1 = the first term
there is a common difference of 3
isnt it geometric series?
geometric is when there is a common ratio
I wanted to understand why
a_10 gives you 28
..?
whats way too low
uhm
I think we messed up here
am i being dumb
the difference between each term is 3
when we add by increments of the same number in a sequence it’s called arithmetic
geometric is when we multiply each term by the same quantity
which is not the case here
For, T0 =1
for T1 = 4
for T2 = 16
its 1, 4 and then 16. clearly theres a factor and not a difference
no
Find T10
which will be your answer
They should look for T11
Because T1 is at the start of the first year
no I meant that T4 should have been 64
ah yes
a sub 1 = 1 (because we start with 1 stem)
and we let n = 11
the end of third year is T4 so yes
Both of them mean the same stuff
if a_1=1 then a_2=3* a_1 then a_3=3* (a_1+a_2) and so on then a_n=3*(a_1+a_2+...+a_(n-1))
so it’s just 3^10
oh a makes sense
59,049 stems
nah if that would be correct then T_0=1 and T_1=3 but its T_1=4
wouldnt it?
oh true
and T_2=9 but its T_2=16
ok im out of my league here lol
its recursive as i sent here
common ratio is 4 right
Ratio*
and 16/9 =/= 4
my bad yes
Idk why this is being complicated here when you had the answer in your first message
Here
You said it yourself f(n) = f(n-1)+3f(n-1)
=4f(n-1)
idkk I just wanted an understanding, which I guess i got. You check for first year, second year, third year, find a pattern, see if its a common series and work with it
Depends on what you call T1.
oh yeah
yes this
ok
well ty guys
i just leave it out to you
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Hi, can anyone help me with the integral of $\sqrt{tanx}$
Aetherfly
$\int \sqrt{tan(x)}dx$?
Why am. I here
ok, so which method do you think you should use
uh
substitution at fist
hint tan(x)=u works well
would be better
you first multiply and divide by $sec^2(x)$
Why am. I here
try it
as in how to think of it?
(dont say intuition)
yes
I won't
I basically want to introduce the derivative into the integrand somehow
to perform a u-sub
as I know that $d(tan(x))=sec^2(x)$
Why am. I here
hmm
so you get $\frac{\sqrt{u}}{1+u^{2\ }}$
Why am. I here
oh
Why am. I here
allowes you to elimiate the root too
hmm
makes sense?
@hoary veldt Has your question been resolved?
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Hello, does anyone know why this change is legal?
Does it have something to do with complementary angles? I know that sin(x) = cos(y) if and only if x+y=pi/2.
yes
but how would it apply in this case?
the other thing I know is that cos and sin are equal at 45°
but I don't quite understand what was done there
no, I don't think that would help here
$sin(\alpha+pi/4)=cos(pi/2-(/alpha+pi/4))$
Why am. I here
@dreamy hull Has your question been resolved?
but how do I get to the cos(a - pi/4) expression?
ah, by the parity of cosine cos(x) = cos(-x)
thanks
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Can someone explain me please, what does "df" over equal sign means in this notation?
In my book about probability it's called upper bound of sequence of events A_n
I think it's some kind of convergence, but what exactly
I see on the internet, there is word "def", rather than "df". I think if that's the same, cause I don't see anyone to use df
but it might be it
I will wait for more answers, cause I am not quite sure
yeah that is why I deleted since I wasnt 100% sure and dont want to mislead you
Defined as
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How do I confirm this operation is closed?
I also have the addition, if needed
Can I do neutral element of addition * vector = neutral element of addition?
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nie wiem
Damn, I really need to understand this.
Cuz if a scalar times the vector comes to something, it also has to be inside the same subspace so it is closed under scalar multiplication.
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help
If I were to add 50% to a number, how could I reverse this? like if I was given a number and was told it had 50 percent added to it, how could I get its original value?
times 2 divide by 3
ty
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Does anyone mind explaining why $\frac{d}{dx}\left(\frac{\sqrt{1^2+\left(15-x\right)^2}}{2.5}\right) = \frac{0.4\left(x-15\right)}{\sqrt{x^2-30x+226}}$ and not $\frac{1}{6}+\frac{\frac{2}{5}x-6}{\sqrt{1^2+\left(15-x\right)^2}}$?
Punisher
try simplifying the fraction, to 1/2.5(sqrt(16-x^2)) and apply differentiation rules
@honest berry go to a closed help channel and open it
good idea
Which fraction?
the initial one, the one you wanted to find the derivative of
like this
now can you find the derivative of that?
Where are you getting the 16 from?
you have 1^2 + (15-x^2) correct?
that changes things then
That's my bad; I didn't indicate that it was the quantity (15 - x)^2
alright then dont simplify, go ahead and differentiate like this, moving the constant to the outside
and letting the inside be
sqrt(1 + (15-x)^2)
step by step, using the chain rule
and tell me where you will get
you are missing something, apply the chain rule correctly
you need to multiply the whole fraction by the derivative of the inside of the square root
so (1/2 • d/dx [1/√1^2 + (15 - x)^2]) * d/dx[1 + (15-x)^2]
if you have done it correctly it should be this
dont forget to multiply this whole thing by the constant at the start though!!
1/2.5
Right. Ok, so that would equal (-1)(15 - x)(1/√1 + (15 - x)^2)
not quite, how did you get the -1 at the start?
ohhh yes, i forgot to write it down on the final answer!
the minus is there in the last step
Right. So, the final answer should then be (x – 15)/6.25(√1 + (15 - x)^2. Right?
nono you have placed the constant outside the derivative so you just multiply it at the end
d/dx[c * f(x)]= c * d/dx[f(x)]
are you there? do you need me to explain any further on that?
Sorry. I just re-derived the original function (d/dx[(√1^2 + (15 - x)^2)/2.5]), and I got a very similar answer to my original answer (minus the 1/6).
^ I thought the quotient rule of derivatives stated that the derivative of a fraction is the derivative of the numerator multiplied by the denominator minus the derivative of the denominator multiplied by the numerator, and all divided by the denominator squared.
Wait. I was right this whole time 😆; the answer I looked up was just in decimal form (namely, 0.4(15 - x)/√x^2 -30x +226)
0.4 => 2/5 lmbo
Anyways
Thanks @tiny patrol
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This is the first exercise in chapter 4 of the book think bayes 2 and i can't understand why they choose the prior for getting a hit as uniform between 0.1 and 0.4? I don't see any motivation for that in the question, imo either you use the info given to make a more accurate prior or you just do a uniform between 0 and 1. Anyone understand this choice? Hopefully this is ok as a statistics question, feel free to remove if its not appropriate to ask that here
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How do I find the center on the ellipse based off the plotted points without looking at the graph?
plug in theta = pi/2 and theta = 3pi/2 to the polar equation
average those 2 points to find center
Thank you that works. 🙂
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Im trying to find the real and imaginary values of the function g(z) = sin(1/z)
Im kinda stuck at (e^(i/z)-e^(-i/z))/2i
euler’s formula for the trig functions?
imma try 2 sec
let z = a+bi first to separate real and imaginary parts
wait how would i then spilt the z=a+bi inside the cos and sin
you dont
1/(a+bi) = (?) + (?)i
then every part would be imaginary no?
because e^(a + bi) = e^a(e^(bi))
wait i can split fractions like that?
1/(a+bi) = (a - bi)/((a+bi)(a-bi))
simplify that
again the last time i was messing around with trig in C i used the taylor series
equal to a/(a^2-b^2) - bi/(a^2-b^2)
yeahh oooh i think i got now ty
now expand into cos x + i sin x in your formula thing
also can you tell me once you have your answer i might need it for a coding project lol
Sure give me little time tho something came up i gotta go for 5 ish min
@balmy vault Has your question been resolved?
wha
well i found a section in my book after i was stuck
sin(z)=sin(x)cosh(y)+icos(x)sinh(y)
i am assuming i can use this property here no?
where z = x + iy? yes definitely
just gonna screenshot this rq for whenever i need brute force complexexp rq
how do x and y relate to z
oh ok
Isnt the real part denoted by x and the imaginary by y?
now substituting that into your formula seems to match that paper
^^ yay
yes i think
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Suppose that two cards are selected at random from a standard 52-card deck. What is the probability that both cards are less than 10?
Since there are 4 suits and each of them has 8 cards that are less than 10 we get 32 cards that are less than 10 in a 52-card deck. To get the probability we divide 32C2 by 52C2?
👍 that's correct, there's a way that has a more simplified answer if you do (chance of first <10 card)*(chance of second <10 card given the smaller deck)
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Yes
@odd sparrow Has your question been resolved?
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im trying to sketch f(z)= zi where Re(z) > 0
so let z = x+yi so f(z) = xi-y
x would still be the real part of the equation so would this be the functional equivalent of x*1
?
which would mean that this would essentially be the same sketching z with Re(z)>0
feel free to ask questions if i didnt properly explain myself
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0,3 <= π^2/8-0.5arctan(N) how can i find n without trail and error?
i'd proly do it by trial and error
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help
you have only considered one possibility, the magnets could be UDU or UUD
is there a chance that the quesetion is written wrong and wants you to do at least 2 pointing upwards?
idk
its unlikely
but i could try the answer for what u said
if so i would have to include UUU
yeah
yh it isn't 10/16 either
yeah you have done the probabilities wrong
oh
the answer i got was 3/4, but working out P(UD)xP(DU) + P(UU)xP(UD)
so the probabilities you are wanting is 3/4 x 3/4 + 1/4 x 3/4
you want to work out P(UDD) as that is the only configuration that will have only one magnet pointing upwards
so would that be 3/4 *1/4
yeah thats correct
you will have to read the question carefully for that one
tbh
i need to work on how i read that question
but would part D u just need to find P(DDD)
yeah you need to find P(DDD) but when you read the question you can see that the left most magnet is always U, so the probability is 0
yyeah exactly
i can try, i havent really done any kinematics for about 3 or 4 years but i can have a look and point you in the right direction if i dont understand it
yeah i can help with that
with this one, if you have the speed of the yacht u = v then they are both heading in the same direction, so the least value of u would have to be going in the opposite direction to v
thats what i think yeah
nope its wrong
i think it needs to include a and b
ah don't worry anyway
thank u for your help
may your pillows be forever cold to have a good sleep
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Help
@wintry moth Has your question been resolved?
quadratic formula
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How much weight of lead do I need for a 52 cm sphere made out of concrete, if I want the desired weight to be 220 kg?
The sphere diameter cannot change, only the lead and concrete volume.
Calculated with 2200 kg/m3 concrete volume and 11 340kg/m3 with lead volume.
52 cm sphere = +- 162 kg, that would simply mean I need 58 kg lead core of a 21,4 cm diameter.
However, while inserting the core, there needs to be taken in consideration, that also the same volume of concrete needs to be removed. Which is around 11,3 kg with that diameter and concrete volume. And THAT again... would mean I need to add another 11,3 kg of lead to the core ?
Which would mean -> 22,7 cm diameter of the lead core, which again removes roughly 13,5 kg of concrete and again calculation of core... I dont think I am going the right way... I would like to reach the exact weight of lead needed, which doesnt get me there by this approach.
(I am long gone from math classes, sorry, be nice to me.)
@urban grove Has your question been resolved?
@urban grove Has your question been resolved?
<@&286206848099549185>
@urban grove Has your question been resolved?
Quick question, do you want the lead inside the sphere to be any specific shape? In terms of calculations one easy solution would be having it as a sphere
Then, the only unknown is the radius/diameter of the lead sphere inside. Let me try and walk you through the theory
Let's fix some notation: $m$ is your desired total mass (220kg), $\rho_c$ is the density of concrete (2200 kg/m3), $\rho_{l}$ is the density of lead (11340kg/m3), $R$ is the outer radius (52/2 cm = 26 cm) and $r$ is the radius of the inner sphere.
The weight of the inner lead sphere is then the volume of it, times the density: $\frac{4}{3} \pi r^3 \rho_l$, the weight of the concrete hull around it is $\frac{4}{3} \pi (R^3 - r^3) \rho_c$, so we have that the total mass is $m = \frac{4}{3} \pi r^3 \rho_l + \frac{4}{3} \pi (R^3 - r^3) \rho_c$. Since the only unknown is $r$, we should be able to solve this equation for $r$, let's do that
Lartomato
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Just reshuffling terms gets us $\frac{m - \frac{4}{3} \pi R^3 \rho_c}{\frac{4}{3} \pi (\rho_l - \rho_c)} = r^3$
Lartomato
goddamnit i'm not asking a question i'm responding to one
Simplifying that and taking the third root, we get
$\sqrt[3]{ \frac{3m}{4 \pi (\rho_l - \rho_c)} - \frac{R^3 \rho_c}{\rho_l - \rho_c}} = r$
Lartomato
If you trust this, then the radius of your inner lead sphere should be 11.487cm
And 11.487 * 2 is 22.974cm, so your estimate of 22.7cm diameter seems pretty good!
and the double-check does pretty well
@urban grove let me know if that helped you! good luck with your extremely heavy spheres
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Looking at a quick proof for symmetry in A^T A
It is the dot product of row i of AT (column i of A) with column j of A. The (j, i) entry
is the same dot product, column j with column i.```
😭 Lol why is this the case? I don't see it
,, (row i){A^T} \cdot (col j)A = (row i){A} \cdot (col_j){A^T}
nyxie9151
not quite like this, row i of A becomes column i of AT, column j of A becomes row j of AT
1st column = 1st row of transpse
@urban shard Has your question been resolved?
yes i know how tranposes work
i mean like
i'm talking about symmetry in A^T A
What does this mean? Maybe i'm a bit dense now but yeah
Could you explain that bit
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hello, i'd appreciate some help with this problem, i know there's probably a formula but i would like to know if i could integrate shape (i) 👍
- if i put it in a cartesian plane, maybe try to get a function for the horizontal crossection, i assume it would be y=(1/2rx+r), because of the gradient and the fact that the integration would start from y=r, is this the correct approach? can't seem to get it right
it's the right idea, but I think your line is wrong since it should depend on h in some way
connect the points (0,r) and (h,3r/2)
then find the volume
r/2h right?
then the line should be y=(rx/2h)+r?
got it, it was (19pi/12)(r^2)(h) thanks
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find the real number m so that the equation has at least two real solutions
!status
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
just try some values. assume x = 0. does the equation hold?
it does not hold
sorry, not x = 0. m = 0.
it does
for m = 0 you get 2 soluions for x?
now look at your solutions a) to f) which contains 0?
did you mean a and c?
a and c does not contain 0, so they cant be right.
yes
I also took the derivative and I got 2x(1/x^2-m)=0, and for m=-e^(-2) we have 1/x^2=-e^(2) which is false. So we also eliminate d
and e and f
so it must be b
right?
why not f?
we have 1/x^2=m in the derivative so m cant be negative
and it need to have at least two points in which is 0
except for x=0
why do you use the derivative?
I thought it would be easier
easier for what?
if it changes sign at a point then it has at least one solution in that interval
m=-1 has to solutions:
just try some appropriate values.
ok ill try
so there is m=e^(-2)
so we check now only d and e
and since we also have m=-1 the answer is f
thank you for help
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quick question, does e stand for joules or p stand for joules
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You want to buy a new sports car from Muscle Motors for $44,300. The contract is in the form of a 72-month annuity due at an APR of 6.05 percent. What will your monthly payment be?
so
hi
n is expressed for the n-th value of a certain period which is annually increased based on the question
so you have 72 months right?
correct
how many years would it be
6
the n would be the exponent you use on this equation
and the i would be the annual percentage rate
which is the interest
right
right
so what's the total price would be by using this formula?
well i have to first fit everything into the equation
after you found the total price, divide it by 72 as you have to find the amount to pay monthly
o the left is what we are finding out
right
44,300 (1 + 6.05) 72. ?
$44.300(1+6.05)^6$
sho
