#help-42
1 messages · Page 35 of 1
right -3 mb
do you know log laws?
i dont remember all of them
well as long as u remember some
u can know this
or u could simply do ln both sides
the second is the inverse right?
so you would have $ln(2^{x}) = ln(3)$
Sarro
Sarro
no
same thing just different variable names
isnt this log_2(3)=x
yes
-2^x=-3
2^x=3
i was showing u a different way
cus i thought u didnt remember all ur log properties
i was taught this way
yep that's right
i started learning them like a day ago lmaoo
fair enough well try to commit them all to memory
for the inverse do the same process
let x =0
to find the y intercept
and let f^-1(x) = 0 to find the x intercept
couldnt i skip the work by just, yk, inverting it?
switch the domain and range, etc
hm well when i plug in x=0 for the inverse
log_2(3) so shouldnt my vertical asymptote be 1.58
no that's not an asymptote
then how do i find the VA of the inverse
log_2(0) dne right
yea
so what makes -x + 3 = 0
yes so that's ur assymptote
3?
yep
so i set the argument equal to 0 to find the asymptote?
yes
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just a quickie but what does the upside down delta mean?
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Did i do this correctly ?
i got 2 as a critical point
what did you get for f'(x)?
well it must be (c) anyways right cause it must have one critical point
i didnt use that method but i just made both equations denominator and numerator equal to 0, and got 2 critical points 2 and 3 then i just tested whether their ranges are positive or negative and found out that only 2 matters
not sure how reliable is that
but i will try to find f'(x) also
wait actually kinda yeah because the derivative for me became very complicated
either way you still would arrive at the same derivative because
$-x^2 +6x -9 \over (x^2-5x+6)^2$ \
is the same as \
$-(x-3)^2 \over (x-2)^2(x-3)^2$ \
$f'(x) = -1/(x-2)^2$
Scythed
ye thats what i got
so you will end up with -1 = 0
so no critical points
so the answer is (c) right ?
isnt x = 2 a critical point because f'(x) at x=2 is undefined
one critical point?
oh wait im so dumb
since 2 is not in the domain in the function
there is no critical points
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I’m sad
Try to not waste a help channel for nothing please

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oh my god i keep messing up pasting
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need help
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can you help me pls
in the figure, NB ⊥ ABC, BL ⊥ AC. Which of the following is correct?
A AN ⊥ AC
B BL ⊥ AB
C BC ⊥AC
D NL ⊥ AC

so you have to choose between a b c and d?
and this doesn't make any sense how is NB perpendicular on a triangle
to be honest, im not good at math at all, i need to do this assignment, but i don't know how to do it 😭
do you have any other data ?
no(
OK so you mean NB ⊥ AB and BL ⊥ AC right?
NB ⊥ ABC and BL ⊥ AC
how the*
i dont know 😭
ohhhh, okay, maybe you can help me with another task
In the figure MA ⊥ (ABC), MC ⊥ BC, AC = n, AB =m.
Write a formula to find the length of the segment BC
√n²-m²
√m²+n²
√m²-n²
(m-n)2
yes
MA is a segment right?
yes
and abc is a triangle? or what
maybe yes
maybe?
photo
oh lord why didn't you send it
sorry(
this?
ye
thanks 
okie
no 
ok bye!
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Q12
Why did we take the derivative of this r vector?
the curve is parametrised by u
this means if you want to know the direction of the curve at any point along the curve
you want to find the tangent vector along the curve
which is precisely the vector found by taking the derivative of the position along the curve with respect to the parametrisation variable
aka dr/du
another way to think of it is to think
if i want to know the direction of the curve at any point
i want to know how does x change as u changes
and the same for y and z
so i change u by du
and check what dx is
and the way to find that is to find dx/du
similarly y and z
so you get a vector (dx/du, dy/du, dz/du) aka dr/du
but how is that change giving you tangent??
I am unable to visualize it
Okay
at any point in the curve it has an x, y, and z
yup
this curve in particular is parametrised by u
meaning this curve has x(u), y(u), and z(u)
do you remember the definition for derivative?
so changing u changes x,y,z along the curve
And u is changed such that the point is always on the curve originally defined
yes changing u causes you to follow the curve
Yeah
change of one variable with respect to another.
and it gives the tangent
Or rather
The slope of the tangent since the change is very small
yeah I am aware of that limit too
Limit h-> 0 for f(x+h)-f(h)/h
We can extend this to two variable, 3 variables as well
We gotta take the derivative...
you can if it is not clicking try to compare it to the 1 variable function
as in f(x)
how that changes as x changes
and that the tangent line can be considered a tangent vector
But but
Uhh
Why???
Like
Why is it giving you the tangent though?
The main issue I have is that
u was not a variable that I was able to visualize in this 3D space
So I can't grasp how changing u is somehow giving u the slope??
you can visualize u as a sort of "time"
Ohhh
Wait wait
I think I got it
oh?
Like
If I imagine only a 2d space
A plane of x and u
Then I can get the slope of how x changes with u
Which is simply the derivative
Same goes for y and z
I am getting their slopes (aka direction ratios of the tangent on these planes)
And then I am calculating their net which is simply their addition
Am I thinking in the right direction?
I have a feeling I made a mistake somewhere in trying to say what I meant. . .
you can plot x(u)
in 2d
in a plane
and find the slope
which is the simple derivative
is that what you're asking?
i think the problem is that u cannot be visualized as a dimension
because you already have x, y, and z
and so in order to visualise it you have to do something else
like make u into some sort of time
But how I'll take the slope then?
yeah
I tried
It kinda failed
i think of parametrising a curve in 3d as filling in that curve as i increase the parametrisation variable
aka as u gets bigger
the curve gets filled
by a colour or by increasing the diameter of the curve
Oh
it's not part of the mathematics, just for my visualisation
So like
It's ever increasing?
Yeah I mean
I won't get satisfied with just the formulae
I gotta be able to see where it comes from
I'll show you some text
yes u is increasing
or maybe decreasing but then you can define another u' that is u'= -u in which case it is increasing again
so yes increasing
and u increasing means the curve gets traced out
gets coloured in
or whatever way you may think of it
Here too they seem to be taking the derivative of the r vector to the point where we are taking the directional derivative
s (which is our u in this question)
Denotes the length of the arc of the curve between those neighboring points
yeah that's the step you take in u
to see how far of a step you take in x, y, and z
$\Delta u$ or $\Delta s$ in their case
Katharine
hold up i'm gonna share a video it's gonna take a lil while
So taking a step in u takes a step in x
And taking a step in x means that we've begun inspecting the neighborhood of the point where we are taking the directional derivative in?
Is that correct?
yes
Thank you so much 🛐
I see
I've understood like the original problem I had
Like why we were taking the derivative with respect to u here
But now I'm stuck at a more fundamental question
Oh wait nevermind
It's cleared
It was my mistake
right
bottom is black cuz my screen is super wide
during this video the blue ball is at a specific value of u in this case starting at 0 and ending at ~10
A tangent to the curve always gives a direction
So we're having this unit direction tangential vector at a point on this 3D curve
And then taking the dot product with the curl gives us DD which is perfectly okay.
But what I want to understand is that
In 2D
We were taking this direction to any unit vector on the xy plane
Why are restricting ourselves to only the tangent at that particular point in 3D curve?
It's an amazing visualization aid
Thank you
Can you explain what you mean by "We were taking this direction to any unit vector on the xy plane"
Like imagine in the xy plane
I have an arrow
When I take DD
I always take it along this arrow
Now this arrow lies in the plane and I am free to rotate it to full 2pi radians where it basically traces out all the angles at any point
Like in this xy plane
I have 3 arrows here
Which is basically just one arrow which I am rotating about the point where I want to DD at
I'm not entirely sure what your current question is?
The tangent vector is for all points that lie on the curve
Um
Is the above clear though?
Then I'll explain the question again
i'm not sure i understand what you mean with the rotating the arrow
Like this
Tangent vector here is along a specific direction isn't it?
yes
the tangent vector along the curve is those two vectors
depending on which one you want
Yeah but it's only two vectors.
The other vectors we're not talking about in this 3D case.
In 2D case
We were taking it along any vector
Were you looking at specific curves to take the directional derivative?
or just take a vector and find the directional derivative?
You could use any vector as your tangent vector
Huh?
How?
Tangent vector is supposed to fixed for a given curve and a given point isn't it?
yes but the curve can be changed it you want
sighhh
my brain melted
the point of 12 is that you have a function F
and a curve
and you wanna know how does F change as you move along the curve
that's the directional derivative
This^^^
Why only along the curve?
that's the question
you're not technically forced to move along the curve
you can pick a different curve
or just a direction
and find how F changes in those cases
No I mean in general too
That's how directional derivative was defined here ^^^
That's what's bothering me so much
i don't think i understand what you mean
can you ask the question
maybe can you give an example of what you did in 2D for comparison
If for the function that is in the pinned message
I move along a different direction rather than the tangential one but I am still calculating DD at that point u=0 only.
Is this a contradictory statement?
then you would have found the directional derivative in a different direction
But its not wrong right?
One point can have infinitely many directional derivatives since there are infinitely many directions in which I can evaluate the dot product of the unit vector with the curl of the function
yes
Finally!!!
but obviously if you are being asked to find it in some specific direction
finding it in another direction would be incorrect
that's very obvious right?
😄
But i think i understand what you are asking
Yes I got it now
I just found out that I had completely overlooked that "along the curve" business
That's why this tangential stuff happened
And then I got confused how I am getting a Tangent in 3D to begin with lol
You can take the directional derivative of a function at any point it is defined and in any direction you would want
For some reason
I am overjoyed to hear this despite knowing that it's the very definition of having a directional derivative 😭
We may have talked past one another for a little bit
Yeahh
But all's well that ends well 
Thanks once again
I wanted to ask you
Can I possibly tag you if I get stuck somewhere in multivariable again?
I felt your way of explaining was very nice overall
You're like the top 2 smartest ppl I know here though 😭
not close, Ann is smarter than me, Ramonov is smarter than me EAC is smarter than me etc etc . 😄
I consider you supreme for now 🙏
I have not met them so I will not judge them at all.
Take care <3
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without solving the quadratic equation 3x² + x - 5 = 0 determine the sum and product of its solutions
I need help with that
if a quadratic ax^2+bx+c=0 has roots a and b
then a+b=-b/a and ab=c/a
you can derive those using the quadratic formula
@cosmic ravine Has your question been resolved?
What does derive mean
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why is this true??
like why does the resulting system of equations follow from the previous equation
The top equation is an equation of the form Xcos(4t) + Ysin(4t) = 25cos(4t). This can only be true if X = 25 and Y = 0
Thank you
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I know that $L(x) = g'(a)(x-a) + g(a)$
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does anyone know the proof for this, its ramanujans summation formula for diverging sums
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@paper quartz Has your question been resolved?
@paper quartz I suggest that this question goes into #real-complex-analysis you might find some more help there.
@paper quartz Has your question been resolved?
it can be done, but I think that due to the volume and time that would be needed for it, discord is not the best place, the proof can be considered as a bachelor's or master's thesis.
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I need help finding the bounds for Ix, Iy, and Iz. I will be using wolfram mathematica to calculate everything so the bounds can be in any...cartesian,
cylindrical or spherical coordinates. Thank you!
For Ix, I am think about putting the bounds in the order dz dy dz.
First, in Octant 1 under: z = (2-2x-y)/4 or x = (2-y-4z)/2 or y = 2-4z-2x
(y^2+z^2)xyz, the integrand, can it be viewed as the yz plane? (y^2+z^2) has radius 1?
z goes from 0 to (2-2x-y)/4
y goes from ?
x goes from ?
@inner pine Has your question been resolved?
If anyone helps me a will venmo $1
@inner pine Has your question been resolved?
@inner pine Has your question been resolved?
okay so what have u tried so far
u just need to pick a coordinate system, find bounds and then evalute the integrals
So whats a good coordinate system, given this is a tetrahedon?
@inner pine
Cardteasiome
yes kind of
okay lets go back to xy projection
how do u draw the xy projection in the first place
Like the ones in Egypt
@inner pine
But 4 sides
or better yet, what are the equations of the lines that define our xy projection?
?
Wait
xy projection
i just want the equations that define the xy projection
given its in the first octant
what are two equations you know
Density
what
You have a tetahedron in the first quadrant
in ur xy projection what are the lines that define it
What
if you were going to draw the graph from a birds eye view
there are three lines that define the graph
Yes
given in its the first octant, what are two lines you know instantly
yes
YES
y = mx +b
0
z = 0
no
xy world
there is no z
whats the equation of the plane
and then after that tell me the equation of the 3rd line
for the xy projection
answer in order
answer in order
It would just be the x y up and down
answer this first
y = 0
x = 0
2x + y = 2
REALLY?!
thats no the plane
Bruh
the plane is 2x+y+4z=2
What is the plane
😫
now u have all 3 lines
My clac teacher is going to beat me
so figure out the x bounds and y bounds
u gotta pay attention in class bro lol
this is basically the end of calc 3
We are in 15 now
y = -2x + 2
-2/1 is slope
So we have
Points on x and y now
That are
😶
But
That’s not
How do you find the intersection points
well id write it as coordinates but sure
okay now whats ur xy bounds
using the graph
treat it like a simple double integral
your z bounds look a bit weird
why /2?
but yeah, besides that ur correct
now just evaluate
For Iy and Iz it’s same bounds?
yes
unless the integrals are very ugly with dz dy dx bounds
in which case u might need to change the order
lol
This is for wolfram mathematica computer assignment so it doesn’t care what the bounds are
ah
using wolfram?
Yes wolfram Mathematica ?
yea wat about it?
YAA
it should be simple to compute integrals with it
,calc integral of 0 to 1 integral of 1 to 2 integral of 3 to 4 of xyz dz dy dx
It’s for a complete different problem
The following error occured while calculating:
Error: Undefined symbol integral
oh
maybe not so much then
idk how advanced this q is gonna be lol
i only use it for simple stuff
probs better opening a new thread
I will
But one question question
When going from a problem, whose density at each point is proportional to the distance of the x y plane
To proportional to the square of the distance of the origin
My integrand is just z
So it would be z*sqrt(x^2 + y^2) ?
distance to xy plane is z
distance to origin is sqrt(x^2+y^2+z^2)
square of distance to origin is x^2+y^2+z^2
Thank you
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Please help me solve this proof
!ss
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ok so this is unit 3 for AB Calculus and I know for a fact that the chain rule is involved in this right?
im just confused on this tiny step
g'(x) = f(x^2-x) * (2x-1)
or would g'(x) be equal to:
g'(x) = f'(x^2-x) * (2x-1)
notice the 2nd one has f'(x) and not regular f(x)
this confuses me because part of the chain rule is like (u) * (u')
but what about the outside?
is it f'( u) * (u')
or just f(u) * (u')
There is no (u)*(u')
When you write f'(u) * (u')
you have f'(u), which is the derivative of f evaluate at u, and multiplied by the derivative of u
it isn't f' times u times u'
sooooo is it the 2nd one?
cause f(x) is still a function from the table
when I said f'(x^2-x) I didnt mean f' times u I literally meant f' of u
f prime of u like f of x [f(x)]
cause this is a table problem
g'(x) = f(x^2-x) * (2x-1)
g prime = f of (x^2-x) times (2x-1)
OR
g'(x) = f'(x^2-x) * (2x-1)
g prime = f prime of (x^2-x) times (2x-1)
you want f'(u) * u', the first one
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e=(-1)^1/i(pi)
Is this true?
$(-1)^{\frac{1}{i\pi}}$?
Jelle
ya
It is true, yeah
Thanks
Because you can rewrite -1
How can i end the help session
With .close
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I am asked to give an example of vector space over R
Does that mean R^1 (literal R, scalars) or R^n?
I mean both of those are vector spaces over R but any R^n is the prototypical example for a (finite dimensional) vector space over R
Any vector space has an associated base field / ground field (or just simply field) so this is asking for a vector space where the field is R
So, is it R^n then?
hahaha yup
That R^2 is going hard 😈😈😈😈
side note - you can have weirder vector spaces over R -> think of the space of continuous functions over the interval! You can add, subtract, multiply by a real number and you're still a continuous function
so there are some spicy examples
that's all functional analysis i.e. infinite dimensional vector spaces!
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This is the differential equation and how I solve it, do I need to do anything after the last step?

Well you wouldn't really need to - when you correct this one, you get y as an explicit function of x
But as for your one, you could just leave it as either form (remove the C from one of the sides in the above line)
The constant +C would be inside the tan, so tan(x^2 + C), but otherwise fine!
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I need help with this question.
"An object is thrown (straight down) from the top of a 220-foot building with an initial velocity of 26 feet per second. What is the position function of this object?"
its thrown down, so y i guess
Yeah I just gave him a clue
I'm just wondering if it's -16t^2-26t+220 or -16t^2+26t+220... Unsure if it's +26t or -26t
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$T = { A \in \mathbb{R}^{3 \times 3} \mid a_{ij} = 0 \text{ for all } i > j }$ is the set of all upper triangular matrices. \
Let $A$ and $B$ be two arbitrary upper triangular matrices and $c$ be an arbitrary real number. We check if $A + c \cdot B \in T$: \
[
A + c \cdot B =
\begin{bmatrix}
a_1 & a_2 & a_3 \
0 & a_4 & a_5 \
0 & 0 & a_6 \
\end{bmatrix}
- c \cdot
\begin{bmatrix}
b_1 & b_2 & b_3 \
0 & b_4 & b_5 \
0 & 0 & b_6 \
\end{bmatrix}
=
\begin{bmatrix}
a_1 + c \cdot b_1 & a_2 + c \cdot b_2 & a_3 + c \cdot b_3 \
0 & a_4 + c \cdot b_4 & a_5 + c \cdot b_5 \
0 & 0 & a_6 + c \cdot b_6 \
\end{bmatrix}
]
Since we know that the product or sum of two real numbers is a real number due to the closure under addition and multiplication for real numbers, it is seen that the requirement from lemma 9.32 holds for the subspace of $V$. \
We now wish to show that the span of the canonical basis is equal to $T$: \
[
t_{1,1}
\begin{bmatrix}
1 & 0 & 0 \
0 & 0 & 0 \
0 & 0 & 0 \
\end{bmatrix}
- t_{1,2}
\begin{bmatrix}
0 & 1 & 0 \
0 & 0 & 0 \
0 & 0 & 0 \
\end{bmatrix} - t_{1,3}
\begin{bmatrix}
0 & 0 & 1 \
0 & 0 & 0 \
0 & 0 & 0 \
\end{bmatrix} - t_{2,2}
\begin{bmatrix}
0 & 0 & 0 \
0 & 1 & 0 \
0 & 0 & 0 \
\end{bmatrix} - t_{2,3}
\begin{bmatrix}
0 & 0 & 0 \
0 & 0 & 1 \
0 & 0 & 0 \
\end{bmatrix} - t_{3,3}
\begin{bmatrix}
0 & 0 & 0 \
0 & 0 & 0 \
0 & 0 & 1 \
\end{bmatrix}
]
[
- t_{3,3}
\begin{bmatrix}
0 & 0 & 0 \
0 & 0 & 0 \
0 & 0 & 1 \
\end{bmatrix}
=
\begin{bmatrix}
t_{1,1} & t_{1,2} & t_{1,3} \
0 & t_{2,2} & t_{2,3} \
0 & 0 & t_{3,3} \
\end{bmatrix}
\in T
]
These matrices to the left of the equality sign have a non-zero number in every entry that is necessary to meet the definition of an upper triangular matrix. Furthermore, it holds that any upper triangular matrix can be written as a linear combination of these 6. Thus, requirement 2 in definition 9.14 for a basis of vector space is fulfilled. At the same time, their entries with 1 do not overlap. Therefore, it is seen that the equation with the 6 matrices $c_1 \cdot t_1, \ldots, c_6 \cdot t_6 = 0$ with $c_1, \ldots, c_6$ in the body only holds for these vectors if $c_1 = \ldots = c_6 = 0$. Thus, the requirements are satisfied.
bed
Is this correct?
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Show that $2^{n+1} + 3^{n+1} and 2^{n} + 3^{n}$ are coprime. I tried Euclide and induction but didn’t get anything
zarblug
Getting to bed but still there
ok right...
ok..
by induction maybe it is possible
$2^{n+1}+3^{n+1}=2*(2^n+3^n)+3^n$
everg
so we just need to prove that $3^n$ is coprime to $2^n+3^n$
everg
Okay nvm
😉
Realized how stupid it was when typing it lol
but prove that $3^n$ is coprime to $2^n+3^n$, its equivalent to prove that $3^n$ is coprime to $2^n$
everg
so its not by induction ...but its a direct proof xD
I was completely oblivious to that part
mh... i think is not totally trivial indeed
Since 2 and 3 are coprime isn’t there a theorem about how 2^n and 3^n are coprime themselves ?
maybe you could use fundamental theorem of arithmetic and see that the first one has only p=3 as divisor
and the second one only p=2
so they cannot have a non trivial common divisor
I guess by saying d divides 2^n and d divides 3^n we can get to d = 1 no ?
That must work as well yeah
gg
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why is the answer to this 68
68% of data falling within one standard deviation of the mean is just a fact you need to know
im not statistical enough to explain why
So I can say 69 and its also correct
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where should i start on this question?
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I've determined all solutions of the differential equation : $y'' + 4y = sin(2x)*e^x$ and now I need to find all solutions of : $y''' + 4y' = sin(2x)*e^x$ I don't know how to do that is there a trick because it's the derivative of the first solution ?
phoestaclies
Should be
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Ive gotten this far with the problem XD what do I do next? qvq
whats the relation between 2^a and 2^-a?
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I'm bieng told this is doable by u substitution, but I'm a bit rusty on that. What u would I use?
we want to simplify the inside of the square root as much as possible so we'll set u = the inside of the square root, i.e. u = 3x + 5
Yes, of course.
I did try exploring that
But I got stuck with handling the x in the numerator
So I figured I picked it wrong?
if u = 3x + 5 we can solve for x
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The propeller of a boat at dock in the ocean will rise and fall with the waves. On a particularly wavy night, the propeller leaves its resting position and reaches a height of 2m on the peaks of the waves and -2m in the troughs. The time between the peak and the trough is approximately 3 seconds. Determine the equation of a sinusoidal function that would model this situation assuming that at equation , the propeller is at its resting position and headed towards the peak of the next wave.
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i have found the complex number x which is -1±i√3/2 what is a faster way to find the value if you input it in the exponents? qvq
ig u could convert it to polar form and then use demoivres
its also a root of unity of 3
so all the exponents that are a multiple of 3 will result in 1 when the complex number is raised to said power
if you are unfamiliar with demoivres theorem
Looks like an overkill
You can simplify x^49 + x^50 + x^51 + x^52 + x^53 to just -x^51 by factoring
Then you observe that (x - 1)(x^2 + x + 1) = 0, x^3 = 1
And use the fact that 51 is divisible by 3
@signal shadow Has your question been resolved?
Was anything unclear in the suggestions?
How djd you simplify -x^51?
wow thats clever
Sorry if Im being irritating rn but why did you -x^51 and how did you get 0 after the factorization? qvq
So that you could have those (1 + x + x^2)'s once you factor out
Alternatively you could just do this
[ x^{49} + x^{50} + x^{51} + x^{52} + x^{53} = x^{49}(1 + x + x^2 + x^3 + x^4) ]
[ = x^{49}(1 + x + x^2(1 + x + x^2)) = x^{49}(1 + x) = x^{49}(-x^2) = -x^{51} ]
A Lonely Bean
The 0 appears because I got 1 + x + x^2 inside the parenthesis
And we are told that 1 + x + x^2 is zero
hope this helps
you also could have written it as a sum of a geometric series a1(1-x^n)/(1-x)
and have gotten the same thing
remember x^3n where n is any integer will always equal to 1 since the root is a 3rd root of unity
lmk if theres something you dont understand i dont mind explaining
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Find the function for a secondary function, that crosses y-axis in 2 and only has one zero point 2
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@glad fossil Has your question been resolved?
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try to find x and y such that h(x, y) = (1, 0)
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help plz with #21 ty
whats the problem?
i need to find the domain and range
yeah, where are you struggling with it
do you know what domain and range are?
kinda, what specifically
domain is all possible inputs and range is all possibe outputs
nice, what do you think the domain of 21 is?
the 1??
i mean in question 21
[-1,1]?
what makes you think that?
because it is across from eachother
im not too sure what you mean by that
but i can see there are points on that line outside of [-1,1]
in terms of x values
so the domain cant be [-1,1]
no problem
i dont understand the graph
what about it confuses you?
it look zigzagity
right numbers, wrong order
also just a note
when you use infinity in set notation
use ( and ), not [ and ]
do you know the difference?
yeah pretty much, [2,3] would mean 2<=x<=3
(2,3) would mean 2<x<3
when using infinity you have to use ) or (
since you cant '=' infinity
for the infinity, definitely )
for the 2 it can be either
just depends if its included in the domain or not
eg [2,infty) would mean x>=2
(2,infty) would mean x>2
in this case, yes
OH TYTY
no worries
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The homogeneous system, Ax = 0, has a unique trivial solution if and only if
λ=/=0 is an eigenvalue of A.
why is this statement true?
i'm not sure how to interperet λ=/=0 is an eigenvalue of A.
do you mean that 0 is not an eigen value of A
think its just lambda is non-zero
I think it is that there exists a nonzero eigenvalue?
if it's just that there exists a non-zero eigen value then it's not a true statement for $\begin{matrix}2&0\0&0\end{matrix}$
Willow
since it has an eigen value of 2, but anything in the span of (0,1) is a solution
if it's instead that all eigen values are non-zero, you can use the relationship between det(A) and it's eigenvalues
well
this is how i interpret it
i thought it was false
and i tried to prove it this way:
its possible my logic was just flawed
i was confused with the wording of the statement
yeah, if you interperet at there exists a non-zero eigen value then your logic holds
It's possible your professor meant all eigenvalues are non-zero
in which case its true?
yes
the statement would be true if all eigenvalues aer non zero
have you learned that the determinant of a matrix is equal to the product of it's eigen values with multiplicity?
i believe i just recently learned that, but not sure, different terminology for the same thing possibly
where you can use determinant with like A-lambda*identitymatrix to find the eigenvalues?
this is how you find eigen values, but we also have that if A has eigenvalues $\lambda_1,...,\lambda_n$ that $\det(A)=\lambda_1\cdot\dots\cdot\lambda_n$
Willow
so effectively, det(A) is only zero when 0 is an eigenvalue
so if 0 isnt an eigenvalue, then A is invertible
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hello
finnaly
What is your question?
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i dont understand why its not accepting it as an answer
idk ask your prof or something
the program is clearly screwed up, it accepted your previous thing
or maybe you need to put r*x
it looks like that's what you did in the 1st prompt
@sinful lion
but it seems right to you
?
yeah it is idk why i asked that
related to that, i was fucking around and i just got it right by accident but idk how to solve it fr
just plug sin(kt) in the DE
ik y''=-2ksin(kt)
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is this right?
and how do I find the relative min?
lgtm
@sturdy willow evaluate the function at those critical properties
and check which has a relative min
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How can i simplify this multiplication problem with the grid method?
Put all terms of the first polynomial in the first row of a grid, the terms of the second in the first column of the grid and fill the grid with the multiplication
@mellow summit Has your question been resolved?
Can you show an example or write down smth like that? Kinra contused and never done anything like thos
sorry, I can't write down, but you can take a look at this guy https://www.youtube.com/watch?v=c5xS-Rig8E4
Multiplying polynomials (grid method)
I used this method a couple of times, but then I simply multiply polynomials "in line" to waste less paper
Oh thanks, but what if theres more than two numbers in one polynomial like in that question i sent
in your question you have 4 terms for the first polynomial and 3 terms for the second, so you have to create a 4 x 3 grid
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!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
consider u = sinx
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1
hi @soft orbit id start like this
nope nvm i dont think that will work lol
Ya, sorry, I didnt think it would work
let me think for a few more mins
Have you heard of Weirstrauss Substitution @soft orbit ?
It looks like we may need to do seomthing like this
@soft orbit Has your question been resolved?
Hi @soft orbit someone mentioned to me that the function is odd around the middle of the interval you're integrating one so we can use integral properties to solve
My friend convinced himself that $f(\pi/4 + x) = -f(\pi/4 + x)$ if that makes sense.