#help-28
1 messages · Page 261 of 1
hey? can you help please?
Sorry, I was busy 
Yes I'm reading this again rn
okay
okay
Z is 61.11% of row total
z+70?
Yeah
And z is 61.11% of the row total
You can use algebra to find Z and the row total for broken string

what is row total though? 100 or 68.70?
It's z+70
Algebra
please guide me step by step its very confusing for me idk why, i am not stupid but still its confusing for me
61.11% of (Z + 70) = Z
okay hear me first
61.11% of the guitars that had broken string were acoustic, right?
then
suppose guitars that were acoustic and had broken string is Z
then Z+70 guitars had broken strings?
oh okay i get it
yeah i am sorry, i am just tired
It's alright, happens to me too
Just use some basic alg to solve for z
Once you know z, you can also figure out the column total and total easily
z=110?
Lemme check
Yess
Then, you should be able to figure out the column total too
It's basic addition 
131 yeah
Then figuring out the total of every thing is easy too
yeah filled the table
Can you solve for x now?
What
To get things straight, x is the acoustic neck repair column percent
X = $\frac{acoustic neck repair}{column total}$
Matcha
i am confused
you wait
listen me
x% of the guitars that are acoustic had neck repair
and the number of acoustic guitars are 131
so x% of 131 = 21?
Which is the same as what I wrote here
yayyy thank you so much
how?
Wdym?
where did you see
I'm just really familiar with Khan Academy
What did they teach
Lol that's normal in Kahn academy atp
I also suffered that when I used it to study
It's also a matter of things looking easier when you are presented the solution than when you are asked to find the solution, i.e. it's psychological related too
yeah, thats very bad 😭
but no, not in this case
Youll get used to it 
?
the questions that are presented is actually easy in khan academy but the question they give us to solvee is difficult
i also dont like statistics and all
Why not 😭
i am learning it for data science
This is still the easy bit of statistics tbh
yeah, thats unit 1
Ik
The other units are more complicated but less confusing tho
I also found this topic, row and column percent, quite confusing
It was harder than the more advanced topics 💀
i like statistics but i dont like whatever this is, i have studied statistics before
Ooh
I seee
in my university
and also my friend who is studying actuarial science said me to leave this topic 😭
Well, if you don't have any more questions you should type ".close"
It was fun helping you out 
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yoo
Alright
just send the question
I'm not sure, can you send the question
this one doctor
There's a mod here you idiot
people can gauge if they can help you after you send the question
its a bot
yeah ofc u are here pal
I just wanted to check you'd found your way to a new channel okay, but alright
@slate glacier yk?
Not sure, I can do it but not in the traditional way, I'm not familiar with it
You can wait for another helper, not something I'm familiar with unfortunately
Polygon with 5 sides is called pentagon, 6 sides - hexagon, 7 sides - heptagon, 8 sides - octagon, 9 sides - nonagon, 10 sides - decagon
Can you now do i?
The shape is a polygon of some number of sides, count the sides and name it.
I feel like he needs help with the second part
To enlarge it by factor of 2 means to make another similar shape on the grid whose each side's length is 2 times larger than the original shape's corresponding side's length.
So like find length of each side, and multiply the side length by 2 so that now you have measure of each side of the new shape that you need to draw. Just draw it accordingly on the grid with the new measurements.
@torn jolt Has your question been resolved?
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<@&268886789983436800>
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"Now calculate the probability that the random values lie within one standard deviation of the expected value
@proven lynx Has your question been resolved?
which part specifically
why did he do the expected value - deviation
this
"within one standard deviation of the expected value" means that |X - mean| < standard deviation
if you remove the absolute values and solve for X, you get that inequality
mean - SD < X < mean + SD
i dont think i quite understand what standard deviation is
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A farmer encloses a rectangular field by fences into eight smaller identical rectangles in an arrangement of two rectangles by four rectangles. He has 600 feet of fencing to build the enclosure and divisions. What is the maximum area of the field? What are the dimensions
of the field with maximum area?
What have you tried so far?
Nothing, I understand I have to use length and width to make an equation but I'm stilll confused as to how
call the length of one enclosure x and the width y
Quick question, do the division share sides or there is a gap between each one?
they share sides
Try drawing it, labelling sides and seeing if you can count the feet of fence he needs
so, you basically have this figure
yes
Could you identify useful measures for this figure?
as to make an equation based on them
length and width
Theres multiple options for length or width, you could measure the total length and width of all pens together, or the individual sides
try to be a lil bit more specific
Do you see how the whole shape is made up of little 'sticks'?
like, we have short sticks, and long sticks
Want me to diagram that?
Yes, would I just be looking for the length and width of one rectangle to get the area
oh, idk, im needlessly jumping back in aha
I'm just trying to give a hint, of how it might be useful to talk about the quantities you said
you said length, and width
maybe we can talk about length and width, in terms of long or short sides
hope that is helpful
you'll have to say if I confused it more
no, it makes sense,, but how would I use the given information like the 600ft of fencing
so all of the short and long sides
they're made up of fence
the 600ft of fencing is all the fence you got
IF you use less youre clearly losing area
and you cant use more
so if we take all of the short sides, and all the long sides, and put them together, we should get 600 ft
That's one equation you can start with
try to count how many long and short sides you have here
we can draw it more uneven if it helps to count
would it be 5w * 4l = 600ft ?
actually no
10w * 8l = 600ft because I only counted half of the full thing
Consider that here we are working with lengths
A length * a length = area
Which isnt what we are looking for just now
tbh this method is harder
I think you're right there are 10 short sides in the shape
I guess you end up with bigger coefficients

@meager spire does this make more sense
and just in case
really you'll get the same answer either way, all thats important is we have a way to count all of the length
yeah
its just that the full w and l make it easier to calculate the area.
Based on this, can you think on how the equation for the whole length of fencing will turn out?
Im confused lol, so am I getting 3w x 5l = 600ft?
so close
again, the width and length are also measured in ft
but the result is not square feet.
If i tell you one of these lines has a length of 20
What will be the total length of the three together?
60
How you came to that conclussion?
I multiplied it by 3 ...
and what about these 5?, suppose they measure 10
LOL im so sorry, I actually have to go now I have a lecture is in 15 min
its 50 tho right?
yes
So, what will be the combined of these two by themselves?
Again, you just stated the left part adds to 60, and the right part to 50.
110
I hope you can see whats wrong in here now.
Yeah, I'm starting to get it
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In this week we'll be learning about parabolas, are they difficult? can anyone give me an example of a question?
Maybe looking at your textbook will be a better way to find the answer to this
Not everyone in the world goes through the same curriculum
@fallen ivy Has your question been resolved?
Find the unique parabola going through (0, 1), (1, 1), (2, 0.5)
There are a lot of interesting stuff about parabolas there’s a lot of theory
They are all relatively simple to understand on their own but there’s much to cover
example?
this is actually a decent use of chatgpt, a "generate example problems"
don't actually use it to solve problems but it's decently good at generating them
until you solve or try to solve it and notice it fucked up somewhere
right don't use it to solve problems
but it could give you ideas of what kinds you might encounetr
considering how op would do anything but open their textbooks, seems like good idea
@fallen ivy Has your question been resolved?
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😭😭
what divided by 5 gives 10 @deep ledge
uhm
also use the data given in the qn
can i use my calculator
its not a unsolvable qn
oh
tell man if i multiply 5 and 10 i get 50?
okay
now if i divide 50 by 5 what do i get?
absolutely
why such confusion in the first place tbh
idk but im 15 so my mom yells at me everytime i get an answer worng
so i get kinda scared
MY LORD
what
U R 15???
hang on, I think the channel is closed.
reopen the channel if you want to continue, OP.
.reopen
✅ Original question: #help-28 message
man these calculations are expected to b handled from a 6-7 yr old
bro
so does OP have any other question?
Here's some advice: if you don't have anything nice to say, just don't say anything
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.close
It's closed dw
you already closed it.
If you have another question, feel free to reopen
well im sorry imma ask my friend to help me then
And it's okay to be behind, we all do things at our own pace.
We are happy to help you too
arl
On behalf of that other user, I apologise
okay
Feel free to reopen and post another question if you have one
Also hullo Hyacine, sorry for jumping in out of nowhere
i only have 12 questions left
regardless, if you have a legit question, you deserve to be heard.
ok
Reopen then?
arl .open
.reopen
.reopen
✅ Original question: #help-28 message
I'm gonna go swimming, so all yours @azure onyx
Feel free to tag me to pin stuff though
ok
I'll be watching, but in case you do have a new question, you can slap it here first, and I'll reply ASAP.
is it 10
yes!
okay, this requires knowing how to round numbers.
ok
have you heard of statements like, "this thing costs $9.50, might as well cost $10"?
oops, ignore that bot.
ok
this is an example of rounding in action. we round to make calculations simpler to handle.
so here, you are told to round to the nearest ten. do you know what that means?
oh? let's hear it. can you round, say, 37 to the nearest ten?
2905
hm? is this the answer to the problem?
unfortunately, your answer is too correct for the question.
i got it
while 35 * 83 is indeed 2905, they want you to round the two numbers first, then multiply them.
which is to say, your answer is incorrect, btw.
so first, we have to round 35 and 83 to the nearest ten. this means that you will end up with two numbers ending in 0. round 35 first; what do you get?
that's... still not the answer to the question, but sure.
aha. this question forces you to round.
that defeats the purpose of learning how to round, doesn't it? I know you did it for the last question, but if you use it for questions like these before learning the concepts, you're not learning what's happening.
the idea is that we want to first know why one answer gives a better estimate than the other.
idk i just want to go to college...
not to belittle or anything, but that's exactly why you should get the basics down.
ok
sure, you can blaze through these questions with a calculator no problem. but are you learning the concepts behind them?
wdym
for instance, the previous question. do you know why 2905 is not the right answer?
why
you are told to round the two numbers to the nearest ten before multiplying. so your answer should end in two zeroes, definitely not a 5. the problem is that you ignored the instructions telling you to round the numbers and calculated them directly.
oh
that's why I said your answer was too correct.
oh
they want you to estimate the answer by rounding, not to use a calculator. if you have a calculator, you don't need to round!
(of course, if the numbers are still hard after rounding, that's fair game. but round first!)
so do you want to go back to the previous question, or stick on with this one anyway?
go back the previous question
alright, let's do it properly this time.
first, a quick idea on what rounding is. rounding is the process of approximating a number (or in simple speak, the process of turning a number into something that is "close enough").
for example, suppose a product is 37 bucks. if you're asked to find the total value of, say, 50 of them, this is ugly math.
ok
but instead, you can estimate the number by rounding the price of the product to, say, 40 bucks. now that's a nicer number we can deal with.
ok
this is called rounding, and this specifically is rounding to the nearest ten (because after the rounding, notice that the last digit is 0).
ok
so going back to the prev. question. one of the two numbers is 83. what would you round it to?
okay
(remember: nearest ten, so the number should end in a 0.)
no, don't round the final answer. round the numbers individually first!
ok
note that I asked to round 83.
round it to 35?
that's too far a round, plus it doesn't end in 0.
ok
I'll give you two choices: 80 or 90. which would it be?
90
is 83 closer to 90 than 80?
wait no it 80
which is closer: 30 or 40?
40
ok
your multiplication thus becomes 40 * 80. what is the answer to this? you'll find that it is very different from the 2900 you've been insisting on.
wdym insisting
you kept telling me and showing me 2900. the final answer isn't 2900 for reasons you'll see when you answer the last question I posed.
because they relate to your question and helps helpers find your original question faster.
ok
also, don't forget the question here.
so multiply 40 and 80
yes.
well they have 0 so im guessing it 0
sure? you can check with your calculator for this one, because it sure isn't 0 (neither 40 or 80 is 0, so).
oh it not
a product is only 0 if either number is exactly 0.
ok
so your answer is...?
3200
and that is the correct answer for that question.
10 more questions to go
sure. which one next? the one you sent earlier with the division question?
it different
sure. send it.
you sent it already, which was why I asked if it was this one.
but either way, let's work on it.
oh okay
so, the question is just a long way of asking you which expression is wrongly rounded.
ok
that is, which expression has numbers rounded too far?
the second one
correct. so the one with the better estimate is the other one.
because rounding too far makes your estimate nonsense.
okay so estimate 800 and 40
now, you may use your calculator to divide the first expression.
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how do you draw in th 3rd bound?
sorry its a little hard for me to see
@upper silo Has your question been resolved?
not sure if its right\
@upper silo Has your question been resolved?
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didn't you come here with this exact problem some time ago
something similar I think
I have a quiz tomorrow, so just reivsing kind of problems I stuggled with earlier
no, this exact one
oh, okay
i distinctly remember it
so here all I need is the mariginal of Y, right
there are 2 routes:
- recognize X and Y are independent and just calculate P(X<=1/2)
- if you don't trust yourself with that, go by the definition the "honest way": P(X<=1/2 & Y>=3/4) / P(Y>=3/4), calculating each one with an integral
I'll do the 2nd
or wiat
*wait
yea, the mariganls are 2x, 2y
so just $\int_{0}^{1/2} 2xdx$
wai
so 1/4
@thick hedge Has your question been resolved?
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<@&268886789983436800> clean up thank you
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can anyone show me how to do questions like these?
Do you know how to solve differential equations @river goblet
roughly but im not very good at them
$$\frac{dy}{dx} - y = 1$$
Adarsh
Does this help you? or give you any idea
would it then just go to dy-y=1dx
$$dy - ydx = 1dx$$
oh yeah
Adarsh
so is this the same as the left side in the question?
Adarsh
This is what I meant
so is this just a rearangement of the question?
sorry im confused with how that rearangement works
From which part are you confused
just in how it goes from this
to this
Do you agree that
Adarsh
im not sure sorry
$$\frac{d(y(x))}{dx} - y(x) = 1$$
Adarsh
Is this fine?
In differential equations, yes
okay i understand
and then you add the y then times the dx to get there
so then where, do you need the ys on one side and xs on the other?
so gos to dy/(1+y)=dx?
Yes
but does integratin not just then give y=x
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.close
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This is what I have so far:
$X^2≥Y; X \sim UNIF[-1,1]; Y\sim UNIF[0,1]$\
So $X=1/2;Y=1$
\sim
wai
X=1/2 ??
where did u get X^2 >= Y
I'd first try to find what values X, Y result in the quadratic having real roots in the first place?
real solns
ah he did yh
Okay, now this amounts to drawing the region of the rectangle [-1, 1] x [0,1] where that inequality holds
Then calculating what proportion of the rectangle that region is
The question I had is what's the joint PDF I'm integrating over here
everything is uniform
You don't need a PDF here tho?
the pdf is just 1/total area
is it 2/3
Independence allows us to do the joint thing in the first place; UNIF allows us to not worry about weighting
$\int_{-1}^{1} x^2dx$
wai
I feel it is, yeah
tq
And it's because of there being no weighting that we don't need roads PDFs
of course we still need weighting
that integral has area 2/3, sure
but the total area is 2
(if you really wanted tho, iirc the PDF of a UNIF[a, b] is something like 1/(b-a)?)
that's what i used to get X and Y
so I divide by 2
got it
tq
So $Y$'s PDF is $1$; $X's$ PDF given Y=y is $1/√y$
wai
is it just √y
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is this vector field consercative
@charred birch Has your question been resolved?
@charred birch Has your question been resolved?
Not if your contour is translated along the x axis
On the given contour, it looks like it though
@charred birch Has your question been resolved?
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Hey, I'm a bit lost on how/why they graphed f0(x) like this. Could someone explain how they did this?
what must an odd function satisfy
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I would need to see the work, but i can already tell there's probably an issue since you should have an n in your sines and cosines somewhere 🤔
also what did you mean "pi/2 between pi/2 <t < pi"
Ill send my solution
i have a feeling i messed up rlly badly
okay well your indefinite integral for bn was fine but you didn't evaluate the integral on your bounds
which explains why you have a t in your coefficients
you also forgot to include the second integral (the one from pi/2 to pi) in your final coefficient
Omg okay ill redo
and thank you for having neat handwriting lol
is this right now?
i probably messed up again somewhere 😭 so sorry
all good, that's what we're here for
you forgot to put a t next to the cos(2nt) after integrating by parts (you put the t the first time but forgot this time)
I think you also plugged in 2/pi instead of pi/2 for both 🤔
it cancelled out, hopefully its right now
wait no
i made maths up
they cannt cancel
this does tho, if im not wrong
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ty for your help
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@radiant rampart Has your question been resolved?
ai helped me cuz yall be sleeping or sum 😢
!done
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hii im so confused why is this wrong?
the derivitive of the equation is -2t-5, right?
Yes
and then plugging in 4 you get -13
and since its negative it's moving to the left
ok so then what am i doing wrong?
you put v(4) = 13
You put 13
wut
wait no you guys are right.
my logic is weird i fear
erm thank you guys have a wonderful night!
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Find the covariance of this dist
[
\begin{array}{c|ccc|c}
& X=1 & X=2 & X=3 & P(Y=y) \ \hline
Y=1 & \tfrac{1}{6} & 0 & 0 & \tfrac{1}{6} \[4pt]
Y=2 & 0 & \tfrac{1}{4} & \tfrac{1}{12} & \tfrac{1}{3} \[4pt]
Y=3 & \tfrac{1}{12} & \tfrac{1}{12} & \tfrac{1}{4} & \tfrac{5}{12} \ \hline
P(X=x) & \tfrac{1}{3} & \tfrac{1}{3} & \tfrac{1}{3} & 1
\end{array}
]
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lifehealer
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when graphing polar equations what would be like a "life hack" that would be really helpfull
graphing polar equations is really no different from graphing cartesian equations, you memorize how common graphs look (circle, cardioids, lemniscate, etc.) and their respective equations, tweak the equation you need to graph into a combination of familiar graphs you can plot, and draw them
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i mean, what easy way are you expecting? just like how you would shit your pants graphing (sin(x))^tan(y) = cos^2x, it's manual work if you can't break the equation down into smaller ones
if you can graph r vs theta on cartesian axes, you can generally figure out what the corresponding polar plot should look like from there
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That's the domain. x is in R - {1}
I mean I understand the note point why it can't be 2 , but then how will I objectively find the sol^n without any help , I mean what kind of exception is this
you confuse x with f(x)
also don't auto capitalize
The range can't include 2. f(x) is in R - {2}
R - {1} is all possible inputs to f(x), R - {2} is all possible outputs of f(x)
put f(x)=y and do magic to solve for x in terms of y
and explicitly note when you have to divide by zero
Ya when X=1
no not like that
bruh
when you solve for x in terms of y
lowercase
LOWERCASE
how would you solve x/(x-1)=69
LOWERCASE
now do same magic with x/(x-1)=y/2
ohhhh
I get it
x=2/(y-2)
so Y can't be 2
Now pls explain the general approach
I don't get it
You've essentially done the general approach
2x/(x-1) = y is "y in terms of x"
x = 2/(y-2) is "x in terms of y"
2x/(x-1) says x can't be 1, 2/(y-2) says y can't be 2
. .....
...
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Given matrices A and B with LU decomposition $A=L_A U , B=L_BU$ prove/disprove that the row space of A is equal to the row space of B
prograce
@solid ruin Has your question been resolved?
when you do gaussian elimination on A, what does that tell you about the row space
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The outline of an object can be approximated by a half ellipse with a semimajor axis of 200px and a semiminor axis of 312px
When thwhen the curve is revolved about the xa xis find the resulting surface area
holy shit, you're still at it
you have mentioned enough terms to make me convinced that you know you need integration. have you... tried that?
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
i don't know where to begin to be honest
@indigo tartan Has your question been resolved?
@indigo tartan Has your question been resolved?
ok, do you remeber the general equation for an ellipse?
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i have been looking at this for like 15 mins and can't think of a relation which fits
@flint moon Has your question been resolved?
Note that an integer $n$ belongs to the $k$th set iff $T_{k-1}<n \leq T_k$, where $T_k$ is the $k$th triangular number. From here, consider doing some floor/ceiling bounding stuff.
Civil Service Pigeon
For some work of mine, i personally did something relatively similar.
The line of thought of it is a bit abstract, but, its analog to the following problem.
Suppose you have n dots you wanna fit in the following structure:
What will be the lowest k st. the n dots will fit without leaving an empty column.
the sequence here is of the form: 2^k
So, you can solve as follows:
Now, in your sequence, the sequence k must look something like this:
From here the notion should be pretty easy, hope that somewhat helps.
Also, as reference, you can use the floor ( log_2 n ) function as your relation
all n st. the result is = k_i are part of the same subset.
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yo
for part e im not sure on how to solve for the solution vector in Ax=0
x=z-5t
-2y+5z-6t=0, y=5/2 z - 3t
z,t free variables [from Bx=0]
from there you should be able to construct your generic null vector - and from that you can make your basis vectors
dude I have 0 idea what you just said
yeah but
are we not solving for each unknown?
we're finding a general null vector, so having unknowns is fine as we're looking at it in the form of a linear combination of the basis vectors
if we know the vectors have the form
[z-5t , 5/2 z-3t, z , t]
then thats the same as
z[1 , 5/2 , 1 , 0]+t[-5 , -3 , 0 , 1]
in which case what is our basis?
i know but do we need to plug back in [x1,x2,x3,x4]^T or ?
z and t are x_3 and x_4
the only thing left to do from where I left it is to write the basis
howcome we dont solve for them by subbing
but you can plug it in to check
what do you mean?
know how if we have exactly 1 solution we always plug in and solve for each variable seperately
why dont we do that when we have a plane or line as a solution
thats essentially what I did, it just so happens that we have 2 free variables which is why we have a space
I set the vector to be [x,y,z,t]^T, multiplied it by B, and then solved for the variables
theres no way to solve it further than I had here, at most I could change which variables are the free ones
wait so whats the point of resubbing anyway? Im trying to understand this so i can see why this worked out
like geometrically whats the point
say you have 1 exact solution
from 3 planes
@glacial pasture did you change your mind?

maybe not
its not that, Im just not great at explaining things in geometric terms
for a single solution of three planes, it would be the planes all intersecting in at one point, in which case we have a definite (x,y,z), no free variables
If we have one free variable, then we have a line - then our planes all intersect along a line e.g [t,2,t+3] is the line [0,2,3]+t[1,0,1]
if i found x=t, y=2, z=t+3
If we have two free variables then our solutions form a plane, so all our planes overlap
if we have 3 free variables then thats just all of R3
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Can someone explain the answer
i don't see the answer
So basically i checked for the extraneous solution and it should
Root(49) =-7
It saids no real solution is it because
7= -7
Or what
!nosols
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So no real solution?
you don't need all of this
notice 10-13r >= 0
so r <= 10/13
but r>=4 at the same time so no real solutions
Oh thanks for that tip
does the problem require you to find complex roots?
Said to like find the value of n and check for extraneous solutions
Seems like the problem wants you to square both sides, find the roots then plug them back into the original equation to check
that's horribly inefficient
Wdym
that's a lot more work than just observe r >= 4 and r <= 10/13
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<@&268886789983436800> not sure what this is but it seems fishy.
probably cheating
yeah test proctors usually get the tests a day or two early and amc b is on the 13th
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thank you lance lance, of lancesquaredland
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I'm not sure how to approach and solve this problem
drawing a few pictures might help 
Given that you are working with a very limited amount of elements, you can prove most of these answers "brute-forcing" your way through
As long as you have some knowledge about functions
can you guide me?
Well, lets start with r as a function P -> P
Do you understand what its essentially doing?
Beyond the description the problem gives
it’s just a function r to P P is a subset of itself?
From the fundamentals,
do you understand why functions are a special type of "relation"?
And what is a bijective function?
relations are just functions basically but with multiple input output can be repeated then bijective functions are those that are injective and subjective one to one and on to
hi?
!occupied
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PT-BR people?
Tbh you are defining relations as a form of function
While,
- Its kinda the other way around
- Still doesnt convey what functions and relations for that are.
Just to give a sense, a Relation (which can be between two sets), is basically a pairing between elements of the two.
sorry this was taught way back and I don’t have my notebook on me to properly define, I kind of just do the equations
As a dumb example, lets say we do a relation between the set "fruits" and "colours"
We can say that "Apple" might be paired, to both Red And Green
Well, a function is basically a Relation , but an element from the origin set can only have one pairing from the other set..
what class is this?
ohh I see
mathematic logic and reasoning
This section is telling you, element by element
whats the origin, and whats the pairing.
yes
So, for a function r(n)
a becomes b
b becomes c, etc...
yeah makes sense
Doing some notation abuse, if you applied r to a whole set of elements a to e
{a,b,c,d,e}
it would become: {b,c,d,e,a}
again and its:{c,d,e,a,b}
So its basically cycling through the elements of the set.
We consider that idea a rotation, since, when applied multiple times, youll eventually get back to the original state.
ohh
Visually it looks like this
r(P) means rotation on set P?
okayy
Arguably, from a theorical standpoint, these are arrays in reality
so order matters for our purposes
now, we define another function f_a P -> P
Which is essentially a reflection instead of a rotation
Its described as using a line from a to the perpendicular in cd
like this is on text but haven’t seen how it’s written
You get this
from the set meaning
You have to consider that rotations can alter the absolute order of the array
Meaning: b will always succed to the right a, c will always succed b, etc...
Well, reflection can change that order.
If we start from the rotation
$r: {(a,b),(b,c),(c,d),(d,e),(e,a)}$
∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴
You get that, as we described, the array $\ {a,b,c,d,e}$ becomes
$\ {b,c,d,e,a}$
that’s the origin right?
∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴
r Is function, functions can be described as a set of "pairs" from the origin to the pairing.
is this the rotation f_a
yes sorry at first before edited it showed the first set
f_a is a reflection, right now im trying to note down how f_a doesnt work like r
$f_a$ instead has: ${(a,a),(b,e),(c,d),(d,c),(e,b)}$
∫ᴄ 𝐅·𝑑𝑟 = ∬ʀ ∇⨯𝐅 𝑑𝐴
yes I recall now sorry
Which, just in case: doesnt change based on rotation
Since it always uses a as a reference
is the reference just another word for starting point?
im mixing a bit general language and actual math words, for reference i mean that f_a is described as being analog to a reflection with a line from a to the perp. in cd
So its uses a and cd as its "frame", which, as we stated previously, the order cannot be changed by rotations
you can probably see that this arrangement is equal to applying r twice.
But the reflection f_a still retains its property of being a line from a to the perp. in cd
With "starting point" i meant the original arrangement from a to e.
Either from geometric reasoning, or set theoretic rational, you should be able to solve for the problem
ah got it
thank you for the visuals as well, helps a lot
I guess for these type its a good idea to draw then solve for the abcd
if its helps you, both ways are valid
1 its pretty easy to show from a set theoretic standpoint given some of the things i just said
yeah for sure
@sonic stratus you're good with your wording I can probably figure it out but what is a) asking for?
Is asking you to check and prove if the composition of r and f_a is equal to the one of f_a and r
in human terms:
If you rotate and reflect, will you get the same as reflect and rotate
I believe no?
go check on the diagram, draw in your own
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Idk how to do this I fell asleep in class
step 0, or in fact -1, would be to uncrop this so that we can actually see the question in full
cause rn im gonna presume that you grabbed sth off Google image search just to troll about "posting a hard question in help channels"
@crystal tree Has your question been resolved?
Whats the name of the class
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Very unsure as of what to do
Obviously the quadratic residues mod 5 are 0, 1 & 4, but I’m unsure as of what to do next
I tried splitting up cases of the possible combinations which would create a Q which is divisible by 5 but there are too many cases
Really? Have you tried enumerating all cases at least?
Since we're considering sets btw, order in which the numbers appear doesn't matter
So 1112 and 1121 would count as the same instance
Oh wow already a mistake
I considered these as separate instances
Admittedly I gave up half way
Alright I’ll get back to you
If I counted correctly there should be 14 cases
I’m guessing from here we find the total number of possible cases
I’m inclined to say 5^4 but I think that would include permutations of the same set
@tidal storm Has your question been resolved?
0 ain't in the set
I wrote 0 as in congruent to 0
Same for all the other numbers
Think I found a bit of a route for myself
There are only 3 possibilities of a Q which is divisible by 5
It depends on the congruency of the individual squares, so there are 3 cases:
#1: 0-0-0-0
#2: 1-4-1-4
#3: 0-0-1-4
I think that if I’m able to calculate the total number of ways that each of these cases occur, then add them together, then finally divide them by the total number of possible choices of 4 numbers from N, I should get the result
Evidently the number of possible choices of 4 numbers from N is N choose 4.
Then based on N I can find how many numbers there are from 1 to N that have squares that are divisible by 5.
And also how many are congruent to 1 & 4 mod 5.
