#help-27
1 messages · Page 115 of 1
Actually no it's not
wait
no it is
Nah I'm just playing with you at this point
I thought it was slightly increasing to its right but I'm just now realising it's actually perfectly flat so it counts
because maximum and minimum is finite so as the end behavior approaches infinity well infinity is non-stop so that can't be our max or min.
so then I guess my question is answered where we can choose to constrain a function at a certain interval and observe the maximum and minimum values
or we can just observe the function in terms of a broad scale and also observe the maximum and minimum values.
Maybe my brain is just not braining right now but what exactly is the problem?
Wait hold up Labyrinth would u mind taking a look at this rq
I'm already here to help so I might as well
Glad I'm not the only one to write in print
I love pen and paper.
Anyways.
I was wondering for maxima and minima do I need to constrain it to a closed interval? Or can it be an open interval, but if its an open interval couldn't it lead to the possibility of the argument below?
Do you need to constrain it... for what?
I'm asking when determining a maxima or minima does it have to be constrained to a set interval or can the interval be open as well. But the only problem is if we make an open interval then we can have the argument below which would be wrong?
Are you asking about showing that it's a maxima or minima?
If I wanna show something is a maxima or minima does the x values need to be constrained to a set interval or can it be an open interval?
If x is contained within an open interval such that for any x' in the interval we have f(x') >= f(x) or f(x') <= f(x) then there must be a smaller closed interval contained entirely within that open interval such that this holds
This logic goes both ways
So unless I'm missing something, it shouldn't matter whether you use a closed or open interval
@mint orbit Does that answer your question? If so, you can .close this channel
@mint orbit Has your question been resolved?
So what your saying is that in both the open and closed interval we know that by definition of local maximum and minimum holds for either scenario. As long as there is nothing that impedes that fact then we know it holds for both open intervals and closed intervals. But my question to you is when you say smaller interval that is not a rigorous statement to me for the definition of local maximum and local minimum to me, because I'm thinking mk well in what specific range do I have to be to ensure that the statement is true. Maximum point c (Local) If point c is a relative maximum if f(c) >= f(x) for all x e ( c - h, c + h) where h > 0 (our tolerance level measure).
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This function is not concave upwards
what makes u say that?
I can find two points on the curve such that, if I draw a segment between them, the segment is not above the curve
wdym
that's a cool property for visualizing concavity
mk tell me why that is
The true definition of "$f$ is concave upwards", that doesn't rely on the second derivative, is : $\forall x,y\in D, \forall \lambda \in [0,1], f(\lambda x + (1-\lambda)y)\leq \lambda f(x) + (1-\lambda)f(y)$
rafilou2003
well it surprises me that you haven't been taught this. So usually when $f$ is differentiable twice EVERYWHERE, then $f$ is concave upwards if $f''(x) \geq 0$
rafilou2003
However, notice than on your light blue point, f is not differentiable twice
I usually just picturize a bowl and align it with the curve
well that doesn't always work as seen here
hmmmm
the only visual way to see if a function is concave upwards is this line trick
thats rlly interesting cus that is essentially the bowl idea but is better. equipped for more functions
OHHHH THAT MAKES SENSE NOW
yea i purposefully made the fist derivative at that point not differentiable at that point
but since that point would not be differentiable for the second derivative
it violates the fact that f”(x) must be positive in terms of magnitude for every point for every point to be considered concave upwards?
yep
interesting because i initially presumed that u were saying somewhere was concave downwards and thus we had a f”(x) < 0, which I found confusing as I know the f”(x) > 0 for every point on there except for the non-differentiable point. This line basically indicated that.
Is there a proof I can see that would be around my level? Also question rafilou when determining maxima and minima does it have to be a closed interval or can we have an open interval as well. Intuitively both should be true, and Labyrinth’s explanation does make sense, but I want ur thoughts in case I am missijg anything.
what are the conditions regarding extrema?
I don't think I understand the part for maxima
Well according to extreme theorem if a function is continuous over the closed interval [a,b] then we have one local maximum and one local minimum
ok so, just draw any concave upwards function on a closed interval?
well in my function its an open interval
(-infinity, +infinity) for our x values
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need help with homework: the question is a 19.5% discount on a flat screen tv amounts to $560. what is the list price?
do i just add 19.5% towards the $560?
<@&286206848099549185> new question
im stuck
.close
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does this look good?
,w x^2 - x + 1 = 0
Looks good Gomez
The answer in one statement wow
Ur free to use the bot btw
oh ok
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For wolfram bot just do ,w (problem)
For simple calculations like
(16*12)-202^2
U can use wolf or calc
,calc (16*12)-202^2
Result:
-40612
You can always just go to the site itself
wolframalpha
,w (16*12)-202^2
🫡 sure thing 🤝
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can someone explain to me how tf this is right
i mean i get the first one is the power of the power rule so that would end up being 6 to the 5th right
$\frac{a^b}{a^c}=a^{b-c}$ :)
FancyBredFries
different exponents
you either need to have the same bases and exponents, or have one be the same to do anything with it†
†you can do some other things to it with logs but that's more advanced
what
alright alright alright
so the last one would be what
because i mean you're supposed to multiply the numbers and add the exponents right
so that should be right then the last one
but it says its incorrect so how tf does that make logical sense
this is certainly helpful
i am getting so much knowledge
BY TALKING TO MYSELF
WOW
hey how are you doing today
good how about you
im doing pretty good
thats nice to hear
yeah especially these days, the world is so screwed up right
yeah i know as of right now i need help with math but no one is here to help me
wow dude that kinda sucks
yeah i know i kinda wish someone would help me
well good luck with that buddy i hope you find someone that can help you
yeah me too i really hope i dont fail my math quiz
ah good luck with that math quiz buddy
thanks good luck with whatever challenges you in life
ah thats nice of you, i better get going
ok, see you around
"Be patient and wait for someone to answer."
lets see how long ill wait
lets set a timer and see how long the wait is
waiting patiently
6 minutes, 33.67 seconds
epic
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so much for help huh
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hi can you help me the equations of this graph?
@wraith pike Has your question been resolved?
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Is this the right approach?
what are you doing on the second line, did you take the derivative of a(t)?
yea
you need to go the other way
a(t) is the derivative of v(t)
so you need to integrate a(t) to get v(t)
@light sable Has your question been resolved?
@light sable Has your question been resolved?
<@&286206848099549185>
yes this is v(t), now use v(0) = 9i+2j to find c
which is by putting 9 into sin and 2 for cos?
mmm no, you just plug t=0
according to this
v(0) = 5 right?
how do i get r(t) then?
wait what did you get for v(0) then
you have to find c first
v(0) = 5 + C
you forgot i and j bases here 🤔
i got that
and that would be for the 5 + C or ?
it's an example of how you should keep the bases after an integral
here you have
integral of -5cost i
= -5 sint
it should be
-5 sint i
yea i got that part
9ti + 2tj + C?
v(t) = -5sin(t)i + 5cos(t)j + C
great. Now according to the problem v(0) = 9i + 2j
so
v(0) = 9i + 2j
-5sin(0)i + 5cos(0)j + C = 9i + 2j
does that make sense?
yea
ok now you can find C
after that, you can find r(t) which is the integral of v(t)
you'll get a constant of integration again, which you can find in the same way because you're given r(0)
did you find 16 from this?
yea
here everything has i and j, so C must have i and/or j too
I mean, C is a vector
otherwise the function wouldn't make sense
could you please show your work? So I can suggest how you should operate these equations
wait why do you write 9i + 2j... for v(0) ? 🤔
you got this for v(t), so v(0)...
v(0) = -5sin(0)i + 5cos(0)j + C
and that must be equal to 9i + 2j because v(0) = 9i + 2j according to the problem, so
-5sin(0)i + 5cos(0)j + C = 9i + 2j
its cuz of this
i see then
yes, so c = ...
yes that's correct
i and j are like "constants"
so sure you can subtract and add them as usual
Now you have the complete expression for v(t) without an unkown C 'cause you already found it
r(t) is the integral of v(t)
yes
When you write the answers, you should probably put all the same basis together:
for example: -5sin(t)i + 9i = (-5sint + 9)i
have it = to r(0) right?
yes
yes
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could someone solve this equations in terms of sinx? the video did it in cos but I want to see if mine one is right
I don't believe the first line you've written here is correct
Oh shoot sorry
i haven't submitted mine because I think i did it wrong
I misread the question.
but I want to see what this would look like if you made sin the main unit you want to convert
I'm thinking through the trig identities and I'm not sure if there is a way to rewrite the right hand side of the equation in terms of sin while getting rid of cos
so only cos?
The solution shown here is the only one I can think of. What is your approach?
That's valid!
yea but where do I go from this?
Sorry, I thought you were asking if there was a way to rewrite everything in terms of sin
yea thats what I have in mind
Now you can multiply both sides by 1/2 and factor a sinx out from the terms on the left side
So you have sinx(cosx + sinx) = 1
it would be better if u write cos2x as 1-2sin^2 x
I did
oh yeah
lol
Unfortunately this is a tricky equation to solve
but thank you for the help
I'll do the rest now
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The answer is B but can someone please help me understand it
also pls tag me if soeone answes
How do we generally find the roots of a quadratic equation?
squadratic formula
i subtracted the 2 roots from the squasdratic formula and dquaster to 2
didn't work - was too complex
Exactly!
You're on the right track! If we let $x_1$ and $x_2$ be the solutions to the quadratic equation, and since $|x_1 - x_2| = 2$, we can then find an equation relating $m$ and $n$
thedude365
What do you mean by "didn't work"?
oh waiiit
i did the exact same thing i did yester again now and got the answer
thank you so so much
got the ans now
Of course, I'm happy to help!
@magic tapir Has your question been resolved?
Since we want to see what $f(x)$ outputs when we plug in $3p$, we first need to find out what the constants $a$ and $b$ are
thedude365
Plugging in the given points, $(p, 4)$ and $(2p, 76)$, gives us two equations with which to solve for $a$ and $b$
thedude365
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I did try this but don’t know how to solve further
@magic tapir Has your question been resolved?
@frosty nebula what do i do next?
I did this and got the answer
you know of any better method?
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yeah
ok then can you write out the coefficients of x^1 and x^2 in (2 + x)^n?
with (n C 1) and (n C 2) ?
not gonna instruct you either way on that one.
ok, great.
now solve this for n.
you might want to know that $\binom{n}{1} = n$ and $\binom{n}{2} = \frac{n(n-1)}{2}$
Ann
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guys I need help with the 2nd question
for the first one this is what I did
so there are n bins
there is 1/n probability for ball to go to first bin
thus it's complement is 1 - 1/n
so that's my answer for the first
is it wrong?
<@&286206848099549185>
I already posted it
<@&268886789983436800> he is trolling
WTF
<@&268886789983436800> he is racist
WTF
i think this is right
can you help me with 2?
also why are you guys allowing n-word
theres a filter on it, but that doesnt mean people cant try bypassing it.
oh ok
okay anyways
so in 1
the bin is empty right
and I got the probability for it
I was thinking in 2, I would just do complement trick again and do 1 - my answer in 1
raised to k
what do you guys think?
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doing a project which will involve making a continuous approximation via a function and some constants to some discrete data. I will need to compare it to the already existing mathematical models for these discrete points. Is there a way of statistically calculating how "good" of an approximation a curve is to discrete points?
@deep kiln Has your question been resolved?
for each point you could calculate the distance to the curve and then sum up all the distances
or if your points are of the form (x,y), then you could take the difference f(x)-y.
usually you would then either square the difference or take abs, then sum
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Solve the system to prove that Ox aka x axis equation does not touch any point of the circle equation
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What are the 2 values of Coefficient in a C euqation like 3y+4x=C with circle center 2;6 a point of 8;1 and a radius of 5
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The height of the base of a regular triangular prism is 2√3cm. Find the area of the lateral surface of this prism if the diagonal of the lateral face of the prism forms an angle of 30◦ with its lateral edge. need help with a solution
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<@&286206848099549185>
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(This is where I’m at)
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<@&286206848099549185>
@pulsar phoenix Has your question been resolved?
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'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
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i need help
can someone explain to me how to do these two problems?
this is for calculus ab by the way
what have you tried?
nothing :( i don’t really know how to do these type of problems
but their the last 2 for the assignment
consider g'(x)
what is g'(x)
i bet @terse notch must be sleepy 😛
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idk how to differentiate this
you can do product rule
this won’t really help, this is sinx/cos^2x
which is again quotient rule
i dont think ik how to do this correctly ._.
its u'v + uv' so u'(tan(theta)) + sec(theta)v'
i think
so i need to derive sec(theta) and tan(theta)
sure
how do i do that
you haven’t did derivative of secx before?
um i dont think so
.doc
yes
try this?
um no
do you see cosx is a function sitting inside an outer function
so you should take derivative of the inside
um
not particularly
I think you should revist chain rule
It’s used to take derivatives when we have a composition of function
which is the case here, we have cosx composed into x^-1
so inner = cos(x) and outer = x^2-1?
Do you know how to compose functions? f(g(x))?
$f(x)= x^{-1}, g(x)= \cos x$ thus $f(g(x))= (\cos x)^{-1}$
.doc
the output of a function becomes input of another
so what do i do with that
f(x) = x^-2
g(x) = -cos(x)
ohhhhhhhhhhh
do i do product rule
if we have f(x) and g(x) we can find derivatives
i think
f'(x) = -1x^-2
idk what to do with g(x)
idk im lost
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so thats what i did so far
i just need
to compare my function m(n)
to another one
and show why its better due to a contradiction
but i cant think of one
log2n - 1 gives contradictions in the base cases and such
so i dont think its a good example
<@&286206848099549185>
@mild yoke Has your question been resolved?
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Yoonie is a personnel manager in a large corporation. Each
month she must review 16 of the employees. From past experience, she has found that the reviews take her approximately
four hours each to do with a population standard deviation of 1.2 hours. Let Χ be the random variable representing the time
it takes her to complete one review. Assume Χ is normally distributed. Let X
¯
be the random variable representing the mean
time to complete the 16 reviews. Assume that the 16 reviews represent a random set of reviews.
what's the mean, standard deviation, and sample size
Complete the distributions.
a. X ~ (,)
b. X
¯
~ (,)
also what is this even mean
Sample size is..... number of samples (usually denoted by $n$
992qqoloy
SampleMean is $\frac{\sum X}{n}$
992qqoloy
Sample Variance is $\frac{\sum X^2 - \frac{\left(\sum X\right)}{N}} {N - 1}$
992qqoloy
And sample standard deviation is the square root of that
I assume you wanted the sample ones since it asks for sample size
The true mean and stsnadard deviation are the expected value and square root of variance
@ashen carbon Has your question been resolved?
Can u show the full problem
Maybe it says something like "complete the distribution table"?
that is the full problem
Yoonie is a personnel manager in a large corporation. Each
month she must review 16 of the employees. From past experience, she has found that the reviews take her approximately
four hours each to do with a population standard deviation of 1.2 hours. Let Χ be the random variable representing the time
it takes her to complete one review. Assume Χ is normally distributed. Let X
¯
be the random variable representing the mean
time to complete the 16 reviews. Assume that the 16 reviews represent a random set of reviews.
Complete the distributions.
a. X ~ (,)
b. X
¯
~ (,)
@ashen carbon Has your question been resolved?
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If it was (x + (a))(b) = c, what should you do?
Then my first step is to?
(x + (a))(b) = c
The b is multiplied with (x + a) so what should you do?
bx + ab?
x+ab?
is division defined for matrices ?
But its (x+a)b = c
x=c/ab ?
a*b= ab
b=c/x+a?
X+4 = 20/5
Yes
X+a = c/b
This is just a standard, non matrix example, where the first step is to divide by d
For your problem, instead of dividing by b, you apply the inverse
Do you know how to find inverses?
So you want to multiply both sides by the inverse of B
That's not the B matrix
Inverse of B is -4 right
No
the inverse should be a matrix with the same dimension
It's suppose to be a matrix
Where did -4 come from?
13 * 3-5 * 8 =[B]
Recall that the original problem is (x + (a))(b) = c
i think it is the determinant
Yes
How do u find inversion
You can apply this shortcut
B matrix is (13,8 5,3) right
Yes
So i need to inverse B matrix?
But use a semicolon to separate rows
1/-4(3,-8; -5,13)
You're missing one more step
?
.
Do you see how you have to multiply by 1/(ad-bc)?
Find the det of B again
Yes that's the inverse of B
Okay
So you multiply by the inverse on both sides
So you will end up with (x + a) = c * b^-1
Where b^-1 is the inverse of b
Yeah
Can you find what c * b^-1 is?
Do you know how to multiply matrices?
Then can you explain how you got that result?
X= cb^-1 - a
Yep, you subtract a on both sides
Yes
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how can i approach this problem
@weary kestrel Has your question been resolved?
<@&286206848099549185>
what
oh so sorry I thought i could ping the helpers
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@brisk raft Has your question been resolved?
It's an approximation
The approximation is too off
It should be much closer
Then you're entering it wrong
I know. I want to know why it's wrong
Show the formula you're following
I based my summation on this
I took the two endpoints out and then incremented the 4 2 pattern
At least, that's what I was trying to do
These x_k alternate 4,2,4,2, yours are always odd
Try changing 2k-1 to 2k on one of them
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Hello can somebody explain to me when I should use permutations, variations and combinations? I generally know what they do but I do not know when to use them in a problem. Last year I variantions instead of permutations or something and the problem went to hell
@dry loom stay put imma help you out
Ok
you have 4 fundamental questions you want to answer
how many options for chosing:
1.with order without repetition
2.with order with repetition
3.without order without rep
4without order with rep
most commonly you will use 3
We introduce sample spaces and the naive definition of probability (we'll get to the non-naive definition later). To apply the naive definition, we need to be able to count. So we introduce the multiplication rule, binomial coefficients, and the sampling table (for sampling with/without replacement when order does/doesn't matter).
I don't think we have ever used repetitions
which's answer is n choose k
@dry loom minute 34:25
I will see it thank you
the YouTube video i sent is precisely what hadarS mentioned
I am in 11th grade just starting and we are doing and exam with all the stuff we did last year so I need to revise this
there are 4 scenarios and depending on what you want to find you pick one out of those
good so the only things relevant are permutations and sets
yea im also doing college and high school combined
im 11th grader also
Nah, there are all 3 types
I understand permutations and combinations but variations I don't see what they are used for
also multisets and sets in order with repetition?
I have never seen these words bro tbh I do not know what they mean they don't teach in english here
Multiset
For example
i guess the words are variations and tuples
i see on wikipedia the words in english
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need help with this
dont understand how to balance this
the one shaped U is "MU"
the other i bhelive is landa the symbols do matter as much but dont geet what i have to do to make them balance
x : 6 + -1[Lambda] = 2 + 2[MU]
i need to do something to balance the Lambda for x and y if both numbers where positive i could times but becausse its negitive im stuck
@astral elk
are those your two equations
not exactly
this should be 10+-2?
yes but for the second one shouldnt it be 10+-2Lanbda?
$10 \pm 2 \lambda = 0 + 2\mu$
riemann
yes that looks correct so how would i cross the two exuations balance them out to get value of lambda and mu?
@astral elk
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how do i find the slope of the tangent line?
they dont give me a point to use or an equation
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How can you tell what the period of a sinusoidal graph is? I'm having trouble recognizing when a graph is one third or one half of its period?
Like this graph for example
I can't tell if the graph is 1/3 of it or 1/2 of it or 1/4 of it
So it would be appreciated if I could get a tip or trick on this^
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Linear Algebra Question:
If I say that the last column, B, is just all 0s, would it be in span {v1, v2, v3} ?
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How's it possible for a solution to satisfy both conditions
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@mental carbon what can x be if {x, 20} is a subset of {2, 7, 20}?
Well its not directly stated
So its impossible
so, if {x, 20} is a subset of {2, 7, 20}, that means that all the members of {x, 20} are also members of {2, 7, 20}
so that tells us x is 2, 7, or 20
which one of those also lets us have {x, y} a subset of {2, 11}?
probably the question also is assuming that they're not listing repeat elements so in that case we'd have x is 2 or 7
I think in your diagram you're saying that y = 20 since you're accustomed to thinking of ordered pairs (x, y) right
So 2,2 doesnt workc
Ya
so these are not ordered pairs, but just sets of numbers
Yes
so {x, 20} being a subset of {2, 7, 20} places no restrictions on y
since the variable y doesn't show up in there at all
Y is given to be 20 in this example
it is not
The question is really odd
{x, 20} is the set containing the numbers x and 20
y is another variable unrelated to these
it would probably be easier if they used variables like m, n because then you wouldn't be thinking of ordered pairs
Ohhhhhh so x = 2 and y = 11
yep that'd work
Hahaha i get it now
easy mistake to make!
np
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Hello,
Y is the midpoint of XZ. Find XY if ZY = 3x - 13 and XZ = 4x + 7
could someone explain to me how to find X? I have the line drawn out just stuck on finding X
@signal drift Has your question been resolved?
notice that XY+YZ=XZ
mhm
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Hello
I got a formular to calclulate the Multiplicative digital root
How would i be able to make ist a function?
wdym by "make it a function"?
the image describes a function
a function doesnt have to be something you can just write down like f(x)=2x
that said, you could just write down $$F_b(n) = \prod_{i=0}^{k-1} \frac{n \bmod b^{i+1} - n\bmod b^i}{b^i}$$
Denascite
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A vector $\vec{v}$ is perpendicular to $\vec{a}=(2,3,-1)$ and to $\vec{b}=(1,-2,3)$. Also, $\vec{v} ( 2*\vec{e{x}} - \vec{e{y}} + \vec{e_{z}} ) = -6 $
Determine $\vec{v}$
Use () for vectors
{} is for sets
And if you want to use { or } you need to add a \ before them in latex
Yeah my latex isnt the best yet 😅
first find any vector c that's perpendicular to a and b
then we know v=tc
You don’t need \ before brackets
rainy
What is vec{e{x}}
So cross product of a and b?
yeah
I think they mean the basis vectors for x y z axis
Yes
I’d suggest subscript but it’s up to you
I also see multiplication of vectors on the last row
That’s not defined
Used \cdot for dot product
v=t(7,-7,-7)
we just need to solve (t(7,-7,-7)) dot (2,-1,1) = -6
Wait I dont get it
Where does 2, -1, 1 come from
Its v.(2ex - ey + ez)
Not v(2ex, -ey, +ez)
Or doesnt that matter>
?
what
💀
this should be my reaction
writing the basis vectors is just another way to notate vectors
$(a,b,c)=a\vec{e_x}+b\vec{e_y}+c\vec{e_z}$
WhereWolf(ping if needed)
forgot the t
should be easy to solve
lets see
Now just distribute the t {...} over the 3 vectors?
Got -3 3 3
which apperantly is correct
-3 3 3?
Yes
what have you done
Long story short
You saying i needed a 't' really helped me
Thanks
Now still gotta work on my latex
🫡
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Need with epsilon-delta limit proof
Ive gotten to this point however Im now stuck
I need it to be the other way around
Im supposed to prove the limit
by appealing to the definition of a limit
Im trying to find a delta in terms of epsilon
try another delta, e.g. 0.5
ah right I see
I tried 2 and ran into same problem
didnt think to go smaller
@long pasture thanm you that worked
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What method to solve this?