#help-10
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Do you know how to calculate scalar product of vectors without knowing the angle between them?
Yeah the product of magnitudes is not 0, their scalar product is
sorry whagts the differnece between their scalar product and the normal product
Also incorrect. It is sqrt((3)^2+(-m)^2+(-3)^2)
ah ok
By normal product I take it you mean product of numbers in R. We do not define product on vectors in R^n like that. One of the products we define is scalar product. The scalar product of ai+bj+ck and di+ej+fk is (ad+be+cf)
If both of these are perpendicular, this product should be zero
ohh ok so in this case
its 5x3 + 3x-m + 1x-3
oh ok i just did that and got m=4
thank you so much
i didn even need the magnitude at all
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I need help with the solution of the following fourier series task. I think I understood the general concept of fourier series, but I have a problem with identifying odd and even functions. Maybe someone could help me do understand these type of questions better ( PS: Englisch is not my first language)
Have you tried drawing it?
And then it also needs to repeat every 2π
Yes, it would look the same between 2pi and 4 pi
I dont know how to draw it in - 2 pi direction
take your graph and shift it left by 2pi
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or post a pic of the problem if you have one
@solemn osprey
seems weird enough yea
in otherwords x^2y''+xy'+y=0=sqrt(5x)
for second order differential equations
where Ay''+By'+Cy=0 is the homogenous form, I just don't know if the sqrt(5x)=0 is extraneous or not
0=sqrt(5x) what
yeah there are two equals
seems fucked up
it could be another way to write a system of equations, not sure
he says it's on purpose
you can't have both of them true at the same time though
we're talking about a functional equation
you don't have sqrt(5x) = 0 for any x
yeah I'm pretty baffled
I wonder if he wants this to work like compound inequalities
is it really a differential equation then
the guy just invented a new field "today imma teach you differential inequations"
no idea, probably just gonna have to take the loss
yea
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To select a team, some rules must be respected. All teams have 7 members and a maximum of 2 girls.
Elsa's class has 28 students, 11 of which are girls.
Elsa's team won the tournament. John is part of the team. A photo will be taken with the team members side by side. Determine how many different photographs can be taken, knowing that Elsa and John are not together?
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I have 4 values how do i make the compound sol
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are you trying to solve x⁴+3x²-4 = 0 for x ?
if not then what equation you are trying to solve ?
and wdym by compound solution ?
hmm okay (although the prefer the term complex solution or solution simply)
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If T(t0) = <2,3,4> then which of the following could be the osculating plane to r(t) at t0?
Answers:
a. 3x+y+z=2
b. x+2y-2z=7
c. x+y+z=5
d. 3x+4y-z=8
e. 2x-y-z=0
Don't know what to do at all 😭
the tangent vector has to be contained in the oculating plane
and you have all the equations of the planes
so you can find vectors that are normal to those planes
and those vectors must be orthogonal to T(t0)
Ohh okay ty
@abstract flame So the normal vector for answer choice a would be <3,1,1,> right?
yeah
Ty
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I'm a bit confused
did you try
|x+5|<=2x
and then u can do
x+5<=-2x and x+5<=2x
and then ucan see which one exists
@vast flare
so x<=5/3 or x>=5
i dont get how the answer is x<=5 though
Same
it should be x>=5 or x<=5/3
But it says only x>=5
are you just solving for x
Yes
But desmos refutes the 5/3 version
send a screenshot
what
well
that is saying x>=5
yea
i was right
cause the shaded part
is greater than
or equal to
5
But what about 5/3?
uhhh idk tbh im not that smart
like sometimes when you get two answers
1 of them doesnt work
Yea but why for this case?
Which country you from?
this is algebra one right
america
Interesting
its just simplifying the two sides
no clue why desmos doesnt accept the other thing tho
maybe someone else can tell
Let's wait for an expert
Cya
gl finding the answer
Apparently Microsoft Math agrees too.
And Symbolab
So -5/3 is somehow dejected
<@&286206848099549185>
how can I help you ?
Figure out why x >= -5/3 cannot exist
what is the exact question ?
See up
And why x>=5 is the only sol.
<@&286206848099549185>
alright I think I got it
Yay
for the inequality to be satisfied you need to find the values of x that will make 2x >= abs(x + 5)
so, if you try and negative values for x the inequality will not be satisfied as 2x will be negative while abs(x + 5) is always positive
that way -5/3 is not a solution
now you get 0 and all positive values remained
nah, not exactly 😅
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I am trying to find all real $x$ where $$\sum_{n=0}^{\infty}2^nx^n$$ converges. I was hoping someone could check my work. I did the ratio test, so,
so that is the interval of all real x where the sum converges, by the ratio test.
is that correct?
So far so good
Is there more I have to do? I thought that was all of it
Endpoints
oh right
|L|=1 is inconclusive
so I have to check that
so when x=-1/2 and x=1/2
Okay so
the first sum is greater than or equal to the harmonic series for all n. By the comparison test it diverges.
the second sum, idk how to determine if it diverges or converges. All I have access to is ratio/root/alternating series tests, all of which are inconclusive
Limit test
I haven't proven that yet
so I can't
I have that series xn converges => lim xn = 0
that gives series xn diverges => lim xn != 0
but not the other direction
so it isn't helpful here right
because it isn't an if and only if statement

It is an if and only if
are you sure? I don't think it is
cause then you could negate it and conclude the harmonic converges
I haven't proven that yet
I find that hard to believe
I have this
series xn converges => lim xn = 0
doesn't negating that give me series xn DNC => lim xn !=0
and not the other way around
the divergence test above is the other way around
What exactly were you taught
Well I mean a lot so I'm not sure what you are looking for me to say. but ill try to list a few things
the series converges if the limit of its partial sums converge
In this image
So you weren't taught any of those?
No, the top line is what you gave
and the rest is me showing why I am confused
I've been taught that the harmonic diverges, I have that proof. And comparison/root/ratio tests
Use this to prove by contradiction
They could be equivalent
could be isn't the same as that they are though
okay ty riemann
I guess I am still a little confused about the difference going on there, but my question is solved
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@willow lynx Has your question been resolved?
The red and shaded area represents all the values for y. first, find the equation that represents the dashed line
you are given two points. how can you find the equation of the line?
the slope is -1/6x
correct i just relized all the answers have that equation
ok do you know what a dashed line means?
none of the points on the line will satisfy the inequality
correct, so which symbol would represent that? the ones with an equal or the ones without?
without
ok, so we can eliminate A and C
its probably B then
now, the shaded area is above the line, so all y values must be...
Correct!
ty i had a few more questions so i can really understand this
what does it mean when the area above is shaded
If the area shaded is above the line, then all values above that line (greater than the equation) satisfy the equation. If the area shaded is below the line, then all values below that line (less than the equation) satisfy the equation.
shading above means greater than while shading below means less than. In addition, we should also take the boundary of the region into account, where a solid line means equal to, while a dashed line means not equal to.
i see
thanks
the + 1 is the y intercept in the equation y =mx + b
ah okay, thanks
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what is this question asking me to do?
sorry if its blatant
and also i think ms is miliseconds however i dont know what cs is
is it centiseconds
yes, centiseconds
so for the first one would i want to convert to kiloseconds? since its 957000
sure that would work
yes, 957 ks
now is there an easy way to convert these?
or kinda intuition
i have these tables
like is there a way to use these values in my chart against the starting value ?
just try the two of them on either side of your exponent and see which one works
wait wym?
ignore the ones for 10^±2 and 10^±1 btw
like if you have 3.8 x 10^16 g then try converting into Pg and try Eg
because they wont be within those values?
for this part
so the two areas nearby?
like for example peta, and exa?
yeah
would that be an option?
when you said avoid those two
would that mean deka isnt an option for b
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Ive done all the other questions, the answer i got is -3.51, can you tell me what i did wrong please?#
you didn't show any work so how should we do that
hmm, -3.51 is an approximation to x^3+4x^2-6=0. Maybe they messed up
I assume this is newton, but I don't really wanna plug stuff in to check
so im right and the website is wrong?
ig thats a possibilty
yup it is definently -2.51
3*
alr i'll figure it out eventually lol
thank u for ur time
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@half quartz Has your question been resolved?
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I'm trying to find the general solutions for this algebreically, but i messed something up:
tan(x + 𝜋) + 2 sin(x + 𝜋) = 0
My work is below (sorry about the messy handwriting)
I used reduction formulas
and then the tangent quotient identity
other than that I just used algebra
does anyone know why I'm missing some answers?
@coarse shuttle you divided 2sin(x) from both sides. How do you know that it is possible?
oh i see
Is your question answered?
Partially. I see where I went wrong, and I’m trying to figure out a way around it. I think I found a way, but I don’t know if it will fix my mistake.
so I’m going to solve it that way and see if I get my other answers. If I don’t, I’ll try to figure out where I went wrong from there.
OK, sure. Do you want to close the issue with .close or leave it open?
I was going to leave it open in case it didnt work
but do you think I should close it and just open a different one if I get stuck again?
ok. I'll leave it open then
yeah i got it this time
thank you so much :)
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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'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
@sharp whale Has your question been resolved?
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I dont know if its yes or no can someone give me a hint or tell me if im right
What's the most recognisable property of an odd function
um
f(-x) = ...
I feel like this depends on the definition of odd function
Depending on whether it forces that 0 be in the domain or not
The reason for it going through the origin or the fact that it does go through the origin
hmm
$f(x) = \frac{|x|}{x}$
neonperseus
-f(x)
0 not in the domain but still odd 
you move it
if I have f(x) = sin x, what does it graphically mean for f(x) + 5
yeah precisely
it moves up
yeah
now if you have a constant term is it ever possible for f(-x) to be -f(x)
it doesn't indeed
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Pls help I have no Idea where to even start off
There's literally no solution between 4 and 8
I don't know what you're expecting
You know there's no solution
So it's impossible to draw any of the mentioned conclusions because they're all wrong
Really?
Im getting smth different
Oh wait
Integer
What
Yeah theres no solution when n is an integer
Is that a typo?
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hey @ruby path
remember that problem u helped me with earlier and said the answer was no
well I got a diffrent perspective
would this be right or wrong?
btw anyone else that wants to pitch in the question is
wrong
The domain of the function may not contain 0 btw
^
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@teal python Has your question been resolved?
ohh u were the person who agreed with me saying no
ok
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Hello everybody, for the past few days I am unable to solve this exercise featured in Advanced high school mathematics by David Surowski. The exerise goes as follows:
I am aware that the solution could be really simple, it is just that I haven't stumbled upon it yet.
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Hey uhm, I have a question. When im looking at an alternating series
Im supossed to either use Leibniz or Neccesary condition, right?
Idk if the second one is called like that
totomc
Depends what you mean by "supposed to", those are certainly things you can try yeah
oh yeah Im mostly talking about borders
But I dont get the difference between these two
In order to use any of those the limit needs to be 0, right?
suppose $$\sum_{n=1}^{\infty} a_n (-1)^n$$ converges. This implies that $$lim_{n\to \infty} a_n (-1)^n=0$$
austinu
alternating series test will tell you this happens when a_n is monotonic decreasing -> 0
the thing is I dont get when to use leibniz or the neccesary condition
what are those?
maybe im confused af
Check necessary first, as if it fails that then you don't need to check leibniz
Sure
If it passes, it doesn't tell you it converges, so you might want to try and check with leibniz
but what else can you do for alternating series
alternating series test
This is leibniz
ah
You can try ratio
Just throw any test at it
(Actuslly I think there are two tests attributed to leibniz but I assume you mean alternating series) thinking of Cauchy, the bastard
i mean the one about if you have series of x_n (-1)^n then this converges if sequence of x_n is monotonic decreasing to 0
Mhm that's leibniz alternating series, and is what I assume OP is referring to
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So I have the work for this problem and got 1/2 idk if it’s correct
,rccw
no, incorrect
How
$2^a + 2^b + 2^c = 2^1$ doesn't mean $a+b+c=1$
Ann
But all the bases are the same
you're trying to take log_2 of both sides, yes?
Why log again?
Oh
it doesn't work if there is a SUM of powers on either side
like for example
2^4 + 2^3 + 2^3 = 2^5
does NOT mean 4 + 3 + 3 = 5
,tex .log rules
shenny17
Then what?
as-is? you get $\log_2(2^{2x} + 2^{2x+2} - 2^{2x-2}) = 1$, which doesn't help you.
Ann
i don't know what that question is supposed to mean
but here is what you could do to solve the equation $4^x + 4^{x+1} - 4^{x-1} = 2$:
write $4^{x+1}$ as $4 \cdot 4^x$ and $4^{x-1}$ as $\frac{1}{4} \cdot 4^x$, to get $$4^x \cdot \paren{1 + 4 - \frac{1}{4}} = 2$$
Ann
@unreal whale
[A] I do not understand what you've written.
[B] I understand what you've written, but I don't see how to continue.
[C] I understand what you've written and am continuing from it now.
@unreal whale Has your question been resolved?
B
specifically simplifying the 1 + 4 - 1/4 here, as doing anything else is basically like going directly backward.
^
Then what
show what you've got.
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I am not really sure what it means by unique
How can i show creativity if they're just equations
It says it in the instructions
The word problems should be created by you and have a unique description
wdym by a unique description
I know a situation where you might wanna solve for the maximum on a quadratic equation. Suppose you have a monopoly on some product, with a linear relation between the price you set and the amount you'll sell, and a constant cost....
can you continue on what I was going for?
Oh so you need almost like a reason for why you need to make an equation
yeah
i can def use this
so basically you want me to find the best price to sell the most amount?
to make the most money, yes
np
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✅
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What step are you on?
1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'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
2
Show your work, and if possible, explain where you are stuck.
I get confused where we assume |g(x) - M | < |M|/2
what is your definition for limit convergence?
I started with taking delta > 0 such that if 0 < |x - a| < delta, then there must be |g(x) - M | < epsilon
But it didn't worked
We say $f(x)$ converges to $L$ is as $x\to c$ $$\forall \varepsilon >0 \exists \delta >0$$ s.t. $0<|x-c|<\delta \implies |f(x)-L|<\varepsilon$
austinu
does this look familiar
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guys i have a question is there a way to use the log base number on keyboard
ok got it thank u
the b representing the base
and then the argument of the log would go inside the ( )
can u send me a ss on how that would look like on wolfram
austinu
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cos x - sec x = 4 sin x . Solve for 0<= x <= 360
So my method is cos x - 1/cos x = 4 sin x
then I multiply everything by cos x
cos^2 x - 1 = 4 sin x cos x
cos^2 x -(sin^2 x + cos^2 x) = 4 sin x cos x
-sin^2 x = 4 sin x cos x
4sin x cos x + sin^2 x = 0
sin x(4cos x + sin x) = 0
sin x = 0 or 4 cos x + sin x = 0
sin x = 0 or tan x = -4
Is this correct?
from there x = 0 or 2pi or pi
My other question is since I multiply everything by cos x, wont there be an answer for cos x?
Looks fine to me but there are infinite solutions not 3
the question wants Solve for 0<= x <= 360
How about the step where I multiply everything by cos x
wont cos x give a solution too?>
It won't change the set of solutions
cosx is assumed not to be 0 since it s in the equation at the denominator
maybe assumed isnt a good word here, we need cosx to not be 0
You do make an assumption so I guess the word choice is fine
an assumption is when you think something is true without being sure
cosx can not be 0 so i m not really assuming
a good example of this is when you make an assumption to solve a problem, you want to prove the statement A is true so you assume that A is not true and you want to get to a contradiction, the fact that you are assuming that means that you don't really know whether A is true or not, but here that isn't the case
there is no "cosx could be 0" scenario
cos(x-45) = sin x. Solve for 0<=x<=360.
How would I do this question
I used addition formula and expanded the cos function
yeah that should be a better method
sinx=cos(pi/2-x)
After that arccos/arcsin of both sides, since the domain is restricted you should get the answers right away
How do I convert cos(x-45) into sin
The formula sheet says cos(x-45) = sin x
but then I will get sin x = sin x
Oh am I suppose to change the right hand side, sin x = cos (90 - x)
then cos inverse both sides
x - 45 = 90 - x
brilliant! thank u
eeehh
x = 135
i dont like it
am i suppose to have 2 answers for this?
45
arent there more solutions?
and 315
do you know the general solution to this?
because question wants 0<= x <= 360
45+ 360n, 315+ 360n ?
but if I got the answer as 135
yeah looks ok...a better way to write this is 360k+-45
what would the general solution to this be
btw i just realised u got 2x=135 so x= 135/2
Will it be 135/2 +- 360k
since you have cos(x-45)=cos(90-x) you will have x-45=360k+- (90-x)
so x-45=360k+90-x => 2x=360k+135, x=180k+135/2
and x-45=360k-90+x which gives -45=360k-90 which is not possible
so x=180k+135/2 is your GENERAL solution
but you want x to be between 0 and 360 so what do u do
Let k be 1
And 0
To get 2 solutions
yeah
the "nice" way to do this is 0<x<360 => 0<160k+135/2<360 => -135/2<160k<360-135/2
and you find the acceptable values for k from there
but when you just want the answer it s much faster to never do this, but good to know exactly what to do if you are confused or unsure
Thank you so much, this helps alot with my understanding
👍
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what is the expected value of head when you flip 2 fair coins?
75% I believe
Wrong
1/2?
@tacit briar Has your question been resolved?
It’s 1 bruh
If you know the answer, why did you open a channel?
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why does an exponential have to be positive
because $e^{\text{real number}}>0$ for all real numbers
frosst
a positive number
to the power of some other (real) number
is always bigger than 0
,calc 0.5^0.01
Result:
0.99309249543704
ok captn obvious
well, that's why this is true
why does the base have to be pos
so its just because we want it to grow
also, -1^0.5 becomes undefined unless you extend to imaginaries
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a is the first value of the sequence. I think question #2 has a typo, the first term should be 107 otherwise it doesn’t make sense
Yes, the “nth term”
so this is the common equation for finding the sequence?
@stable apex Has your question been resolved?
What do you mean by "this"
It's for finding the nth term of the sequence
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A motor boat whose speed in still water is 18 Km/hr takes 1 hour more to go 24 km upstream that to return down to the same spot. Find the speed of the stream.
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
well... i did that in rough section😕
sed. do u remember ur answer?
i got an equation 540 + 84x - x^2
i see
well 24/t = 18+x and 24/(t+1) = 18-x
so 24/t + 24/t+1 = 36
so t = 1 (hour) or -0.6 hour
what was it?
it happens
well good u found ur mistake
are u able to get the correct answer now?
nice
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Can I please have some help on this question?
Show your work, and if possible, explain where you are stuck.
I am unsure how to attempt the question but have considered 8-H as the empty space
for part b) 96 is the volume but I am unsure why it asks to minus 1/3s^2(8-H)
also, which part am i differentiating?
I have also considered the rate as being dV/dT
for part a) am i able to sub in 6 for s and show when h = 0 s = 6
@spring goblet Has your question been resolved?
Do you understand how similar triangles applies here?
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Hello, I am having trouble with this pattern, may someone help me
And maybe give me some tips on finding patterns quicker, as a have an upcoming exam
I*
you can use backslash to escape
thx
!nosols
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
ah srry
try adding the numbers, finding their differences, or multiplying them
otherwise, there isn't a fixed way to solve these
and you likely won't see them again at a higher level, since they can have multiple answers
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I need to get the basis of this vector space
Can someone give me an algorithm of how I can do that
I am lost on how to proceed
try to isolate z from x + y - z = 0
find the general form of a vector in your subspace
wdym with general form
oh hm
x+y = z
so (x,y,x+y,w) or?
do I have to find a generating system?
.close
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yes
try to express that as a linear combination
.reopen
✅
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Hello, I need help
Can someone please explain to me why the fourth line shows the anti differentiated substituion thingy as added rather than minused
Like it is anti differentiated and then the upper and lower bounds replace x as normal\
but why is it added instead of minused
bc the definite integral formula is F(b) - F(a) iykiwm
there is a minus in the antiderivative itself
OHHHHH
it would be -(-cos(...))
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Hey i need to know wheth3r im doing the right thing
have you learnt polar form yet?
Yes i did
you can use it here
But the question says working entirely in cartesian form
to check your answer
I think so
alright thanks, real quick tho...how does the sqroot 2/2 10 work
is tht an improper fraction?
or do i js times sqroot 2/2 and 10 to get like a proper number
coz whn i try to solve this on the calc, it doesnt let me
they are the same thing
ye but like the calc doesnt like it js like tht
what did you enter into the calculator
it gives me a syntax error
hol up lemme show u
was it “10sqrt(2)/2”
because it means multiplication
so put a * in the middle?
yes
did this work?
i got 7 sqroot2 / 20
i dont have the ans key so i cant tell if its right
but thts wht i got
even if you don’t have that, you can still try verifying by using the polar form
yes
arctan ( b/a), if you remember
what do you mean
i use to a ti but it isnt charged atm lol
Ah ohk nvm
try to use exact form instead of decimals
gotcha but how do i divide that
like i got tht ans then?
divide what?
like tht
go back and replace all decimals with their original form
its only one decimal...the 53.13 one

does that contradict what I said
nah im js saying
do you know how to divide polar forms?
do u just uhh divide the r and subtract the theta?
yes pre sure but thn i end up with 0.5 (8.13010235 cos theta - i 8.13010235 sin theta)
use exact forms, not decimals. arccos 0.7071 is unclear, but arccos sqrt(2)/2 is clearly 45°
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is this correct?
5/11 ≠ 0.45
You used decimals instead of the exact form, you could use ≈ instead of =
oh ok ok
writing 5/11 cis -pi/6 is perfectly fine
aight thank u
otherwise it all looks correct
thanks
has your question been resolved? @strange sequoia
yes thank u
.close
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Is this the correct answer? Since the answer for solving the equation is )20+_ sqrt-404 ) /6
Please don't occupy multiple help channels.
@glacial tree Has your question been resolved?
Top G
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Maybe they made a mistake or something because I also can't see why N is an empty set
for all t in R
Shouldn't it be an infinity set?
But in what way would that make it an empty set?
It's set of all x in R^2 that satisfy following property:( x = t[1, 1] for all t in R)
does there exist some pair of numbers which equals t[1, 1] for all values of t?
which equals 1*[1, 1], 4*[1, 1], -6*[1,1]... at the same time
Ah right, only [0,0] i guess
This is not what "for all" means in set theory though
To be honest I do think he is right tho
Just don't really know about the [0,0] case
What's your interpretation?
x=[0,0] wouldn't work. [0, 0] doesnt equal 1*[1, 1]
The usual interpretation is that this is a line of y = x
ah ye haha indeed
That's why there is "some" in the question above
Yeah, that's just a really odd way to phrase it, is this pre-university?
I dont think it's odd actually
maybe it would be clearer with parenthesis
but otherwise it seems ok
I've personally never seen it, any time I've seen "for all" it's meant the same as "∀"
it means
I have no clue, was helping someone else but found it strange in the beginning aswell, but for me MethIsAlwaysRight his explanation makes sense
N = {x ∈ R^2 : ∀(t ∈ R)(x = t*[1, 1] ) }
this set should be equal to empty set
No, that's my point, it doesn't mean that
Because that's not an empty set
You claim that this is not an empty set?
consider x = [1, 1]. Now in order for it to belong to that set, it must be true that ∀(t ∈ R)(x = t*[1, 1] )
i.e ∀(t ∈ R)([1, 1]= t*[1, 1] )
now consider t=4, in order for condition above to be satisfied, this particular example t=4 must be satisfy (necessary condition)
hence [1, 1] must equal 4 * [1, 1]
which is not true, so [1, 1] isnt in that set
Alright thanks for the help @trim portal , you guys close the channel after you done with your convo?
Or can I close it now?
You can close it I guess
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i simply dont remeber calculating with cyclic numbers i guess
when i look it up modulars come up and i dont jazz about it...
cyclic numbers?
also is that . meant to be multiplication?
so $0.2\overline{7} \cdot A = B$
Ann