#help-23
1 messages · Page 348 of 1
[0,1]?
Ahhh, okay. I get it.
Interesting
So, the sequence we chose earlier, could we also have chosen another one that approaches 0?
Oh, and, by the way, thank you. This has been very helpful so far! :)
Wait are we done
Do you understand the second one
Oh also I just realized
I gave you a proof which is completely different from the notes 
Yeah in the notes they're just moving over entire intervals
.close
I feel like this has been the wrong lecture to be absent at... haha
Oh, alright, thanks.
Yeah early set theory is weird
Just take comfort in the fact that you will never have to do this shit again
Haha, I do not know if it brings me much comfort right now... The exam is soon and I feel rather lost hahah
Oh god
Good luck
If you have any other questions, feel free to ask
And feel free to tag me in the future
Thank you so so much!
Anyway, I am going to go do some revision work now and hopefully understand the proof of the Cantor-Bernstein-Schroeder Theorem in a bit.
I've never completely understood it myself
Gonna be fun trying to explain it to someone else lol
Maybe I'll finally understand it
Hahah, well, perhaps later if I have questions I might tag you hahah
I am evil like that
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is p = p_0 + rho g h (rho is fluid density, p_0 is atmospheric pressure, p is pressure at depth h) valid in fluid dynamic problems?
no
there it depends on v and a too
bernoulli eqn or navier stokes would be valid
a rule of thumb could be to apply it when pseudoforce is absent
@grim plover Has your question been resolved?
hmm actually i was solving an efflux velocity problem
and the solution found the height of the container by equating the pressure at the bottom (given) to p_0 + rho g h (where rho was also given)
but i was a little off thrown since due to the hole the fluid was flowing out, and we were applying bernoulli eqn to find efflux velocity
it’s valid only if the fluid is basically at rest or moving very slowly so in that case, pressure changes mainly due to height... but in dynamic cases like efflu, you should use bernoulli’s equation since velocity affects pressure too
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yeah that makes sense, even though the fluid was flowing out, using p = p₀ + ρgh at the bottom is fine because it’s just giving the static pressure at that deptj
bernoulli’s equation then uses that pressure to relate it to the velocity at the hole
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This is a question and a sample solution
I did the exact same thing in my solution when trying it, except I chose x = 0 instead of x = 1
So I got sqrt(4 - 0) in the dominator instead of sqrt(4 - 1) like they did
So I got 4E for my answer and they got 3E
Is my way of doing it still valid or not?
|x| should be greater than 0
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Does this look correct?
@ripe ravine Has your question been resolved?
Looks correct
@ripe ravine Has your question been resolved?
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solve $\in \mathbb{R}$ the equation:
$| 1-x | = 2|x| - 1$
so i should solve based on three cases , 1-x<0 , x<0, 1-x>0 ?
1-x>0 and x<0 overlap
Correct
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Can someone explain what's going on? Why do we take the sum of sin 2kz, why is it 2k and not just k, how do we get those sums after integration? Istg you can't learn anything from these solutions, same as trying to learn math from Wikipedia
@prisma scarab Has your question been resolved?
you're leaving out too much context to answer your question
you can also just make your own more understandable solutions if you don't want to read other people's work
@prisma scarab Has your question been resolved?
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Abstract Algebra - how do we go from (x + 2y + 4) * z to x + 2y + 4 + 2z + 4?
your operation is $x \star y = x + 2y + 4$
ExpertEsquieESQUIE
$\star$
Mr. Gamer 🇵🇸
Cool!
then $(x \star y) \star z = (x + 2y + 4) \star z = (x+2y+4) + 2(z) +4 = x+2y+4+2z+4$
ExpertEsquieESQUIE
basically you can just note x+2y+4 as Alpha or something to not get confused
stars in maths woah
it's a law of composition
ohh ok ty
Ok and then how do we go from that to z + 2y + 2z + 8?
Where does the z come from?
typo prob
I think so
wdym anyone else
your opinion is not valued.
I think so after you mentioning typo warrants skepticism
I don’t think it’s a typo
Notice z is found on both lines
I had high hopes for you, Expert
its a typo in both lines
Do you think so or know so?
One wonders hard why you don’t get help
@astral yacht Has your question been resolved?
You are probably right, no sense in talking that way 😉
Why does x + e + k => e = -k?
Hi!
x * e = x + e + k
By property of the Identity
x = x + e + k
Now, you could use the cancellation law (if you have proved it), then consider that ||every element has a unique additive inverse.||
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hey i need help with cal 2, trying to comprehend finding the limits of a sequence. pweese help me
I might be able to help. Learning the same stuff at the moment. What kind of sequence?
should i type it out or should i screenshot it and drop it here
Screenshot is better (I just learned that too. 😅 )
i understand the concept of the quotent rule which isnt in here but im not exactly sure what to do here
Hmmm... my immediate impulse is to expand the squared term then divide the top and bottom by the highest-degree term in the denominator.
Does that make sense? It's not any different than taking a limit at infinity.
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I need help with Lagrange multipliers with multi variable calculus, here is my work for the question I’m working on and I will attach my question in a second
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
2
please ping me if you can help me :) i am tabbed out of discord in the mean time
<@&286206848099549185>
Yes?
I see that you are asking for help
may I assist.
yes please!
i am mostly just confused on isolating the x and y functions but i don't know if i'm on the right track
do you need more of an explanation of where im stuck?
one secont
yes
slightly vague
do you need the functions to be separated?
the conversation will end in 120 seconds whom inactivity
ok
so i took the partial derivatives of Cx and Cy, set them both equal to lambda, set Cx=Cy and started solving for x and y but i think i would get that y=y if i continued to solve for y. What parts am i missing with my systems of equations?
did you miss a relationship between x and y?
lagrange multipliers only have partial derivatives of x and y, and the constraint function.
so three equations
do you know about multi variable calculus?
no, I have not reached that point of extent.
i was going to ask earlier if this was calculus, but you were afk
Unfortunately, I cannot help you with something I can’t even help myself to.
it's okay, thank you anyways
Much welcomes, I’d like for you to enjoy your day.
@grizzled sun Has your question been resolved?
@grizzled sun Has your question been resolved?
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Its in german can somebody help me with the gauss algorhytm like how do i create one out of it
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I don't get it
Hm
ikr
lol
Tf is ts 😭🥀
ikr
LMAO
Handwriting harder than the question at this point 😔
He writes his “the” as “me” and it’s pissing me off.
Lemme get pen and paper I’ll give this a try
lol lmk if you need me to rewrite the q
like the questions after this one are really simple so idk what's wrong w this
tf is the venn diagram doing is it in percentages
fucking why 😭 nobody does that
ong lmk if the question is messed up
Ahh
The question is solvable with just two bits of information
you can show one is definitely wrong, and I assume that since at least on of the venn diagrams is right, it means the other is right.
"School has 600 students"
"66 play hockey exclusively."
66/600 = 0.11 = 11%
The left diagram states that hockey exlusively is 12% - this is false with the actual data.
The right diagram says 11%. True.
🤷
but fucking hang on
naive by me
But wait.
"11% of people play hockey and cricket."
let me try again
the right venn diagram does not accurately show this?
I could be missing something but yeah that says 66 should help you
like in the mathcord? or in this help discussion
yeah this question got me so cooked
ts basic venn diagrams too
yeah i think it's c
they forgot to write exclusively several times too
I was confused cus I thought it was 60% hockety ty
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hi, just would like to clarify is this is the right way of thinking abt this. if we consider that a subset does not contain 1, then we have need to consider the rest of the set, {2, 3, ... n}, which has size n-1, and we need to choose r elements, therefore, we get (n-1 choose r). if we consider a subset that contains 1, then we have can again consider {2, 3, ...n}, and we only need r-1 elements, so we get (n-1 choose r-1), since either a set containing 1 or not containing 1 are the only possibilities, and then this would be equal to (n choose r)?
Sounds about right. If you want you can also prove the identity algebraically
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can someone do this please so i can check if im correct
not how this works
see
well im asking because im really not sure im right
do you mean i have to post my answer?
yes
it's much more efficient to show your work so someone can see if it's correct or find a mistake
@worldly knot Has your question been resolved?
@worldly knot Has your question been resolved?
@worldly knot Has your question been resolved?
<@&286206848099549185>
@worldly knot Has your question been resolved?
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idk why it's so difficult for me to understand how the simplification works
what rule said 3ln|x|=ln|x^3|?
,tex .log rules
yeah makes sense
so raising everything with base e
how does e^ln(x^3) + e^c turn into e^C|x|^3 ?
I don't get why it's suddenly multiplication
$e^{\ln\abs{y}} = e^{\ln\abs{x^3} + C} \implies \abs{y} = e^{\ln\abs{x^3}}\cdot e^C \implies \abs{y} = \abs{x^3} \cdot e^C$
facepalm
basic log rules that I somehow forgot made me spend forever on this problem
thanks for the help, I get it
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I'm stuck on this problem. To be honest I only know a matrix is symmetric if it equals it's transpose
and that u^T v =0 means u and v are orthogonal
what have you tried
well I tried since A is symmetric A=A^T so A^Tu=lambda u and A^Tv = Bv , I just substituted it in
Yeah that's not very helpful
because we want a u^T to appear somewhere
what happens if you take the transpose of both sides of $A\vec{u} = \lambda \vec{u}$?
Ari
I tried this by the way but getting nowhere
I think it's $$ (Au)^T= (\lambda u)^T means u^TA^T=\lambda u^T $$
Unknown
Yeah like I said just swapping A with A^T doesn't do much since you never get u^T to appear
Consider this
If we take transpose of both sides we have
u^T A^T = lambda * u^T
I use transpose property (AB)^T=B^TA^T
Ari
Now, we want there to be u^T v
so multiply both sides by v
and see if you can finish from there
maybe try $$ u^Tv = A^-1 \lambda v u^T$$ and maybe set it equal to zero
Unknown
Ari
What's another way to write Av
May I have help with a question
based on what you're given
!occupied
Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #❓how-to-get-help for instructions).
well by definition A^-1A=I and I doesn't affect anything
go from here
beta v
Sure, but then you're introducing things that aren't really going to help you (e.g. A^-1) so this isn't the best approach
Ari
do you see where I'm going with this
maybe, I guess you can move right hand side to left and factor u^Tv
that works yes
okay I think I solved it using your method but how did you know to transpose on both sides
great!
Remember that our goal is to show $u^T v$ = 0
Ari
But we don't have $u^T$ anywhere in our given equations
Ari
so you can make one by transposing both sides of $Au = \lambda u$
Ari
but isn't this just manipulating the equation
so what was wrong with my attempt
well you probably saw that you weren't going anywhere
main reason being that you never made u^T appear anywhere
thus making it difficult to prove something about u^T is true
on the last line what if I took transpose on both sides there
I could use fact that (C+D)^T= C^T+D^T
possibly
You're welcome to try it out
yeah it didn't work out
@lean nexus Has your question been resolved?
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Dot product hw, can anyone explain how to get 2?
I assume we use the formula scal sub v (u)= u dot v /|v|
@west goblet Has your question been resolved?
<@&286206848099549185>
ah
usually I see that called proj_v but now that you have the definition, what's your doubt?
actually wait no
that's different
We don’t know k
it's the magnitude
5k -4k +2k =3 K
$\hat k = (0,0,1)$
gfauxpas
$$\hat i = (1,0,0)$$
$$\hat j = (0,1,0)$$
$$\hat k = (0,0,1)$$
gfauxpas
pure mathematicians are more likely to use e_1, e_2, e_3
sure
also
the "hat" generally means normalized vector
good to know that
unit norm
magnitude 1
I see
so you might see something like
$$\frac{1}{\Vert \mathbf y \Vert} \mathbf y = \hat {\mathbf y}$$
gfauxpas
Sorry but what is double absolute value?
magnitude of a vector

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can anyone help me with this problem 😄
i tried thiss
Use the equations of kinematics
what is ... that
hmm i never seen these equations before
You must have seen if you have studied the Newton's laws of motions
i think that is physic
Yes
yea im didnt take physic yet...
sorry, i just didnt know what those equations are
this is my calculus I hw problem
These are supposed to be solved by calculus?
ye i assume
Velocity is integral of acceleration IG
yes
@sinful thicket Has your question been resolved?
Okay so velocity is v(t) = -1.6t + c
Now at time t = 0, what would be the velocity
wouldn't be 0
i dont see they give me any initial velocity
so i am assumming that initial velocity at t = 0 second is 0
right, but do i set the equation v(0) ?
Yes, so what would be c?
so c would be = 0
Okay, now v(t) is simply -1.6t
Also velocity is just directional here, so we can simply say 1.6t in downwards direction
or tbh IDK how particular they are, let's just keep it in negative
So now we've answered the 2nd part
simply find v(29)
And for distance, integrate -1.6t again
Nice dude!
But pretty fun to debunk
Yeah man, well at least now you know how to work with this
I think you’d assume the rock starts from rest
Yeah because it was "dropped", they play with words, if it was dropped, that means its initial velocity was 0
yea, the other problem they gave me initial velocity
Yeah
Yes, if nothing is given and you're sure there's no other way to solve it or find it, then you do have to assume that
Definitely
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I need to find the area bounded by x + y = 2, y = x^2, y = 2
Can I do it like that:
x = 2 - y, x = sqrt(y), y = 2
Then we need to find (an)other y point(s)
2 - y = sqrt(y)
y = 1
And then we compute integral from 1 to 2, and the integrand itself is:
sqrt(y) - (2 - y)
Am I right???
yup precisely
wait what did you get as your solution?
alr lmk
luckily a pretty simple one
(4*sqrt(2)/3) - 7/6
wait I haven't realized that the resulting area actually has two regions
Apparently I need to calculate the right one, since the task says it's bounded on the right by y = x^2
My solution is still correct?
imo its easier to compute two integrals. one for x from 0 to 1, the other from 1 to wherever y=2 and y=x^2 cross
(the first integral corresponds to a triangle so you dont even really need to calculate it)
1 is just where the red and blue function intersect? So is it how I can find the area for any triangular region?
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8/17 × 9/ 3 sqrt 34 should = 72/51sqrt34 right? Is there something wrong with my solution?
,rotate
why do that
when you could just do $\frac{72}{51 \sqrt{34}} \cdot \frac{\sqrt{34}}{\sqrt {34}}$
south
actually, what's the original question?
excessively splitting components led to violating order of operations
,rccw
you also seem to be conflating multiplication and addition of fractions
I rationalized the 2nd fraction into 3sqrt34/34 then multiplied that with 8/17.
Multiplied both fractions by the other's denominators to get a common fraction
Then just added the numerators from cross multiplication then adding both.
Which part did i mess up?
Im going to recheck
what's "cross multiplication" doing here
you also seem to be conflating multiplication and addition of fractions
Followed some old notes
Yea that, alrighty
$$\br{ \frac ab} \br{ \frac cd}$$
is simply
$$\frac{ac}{bd}$$
ραμOmeganato5
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is anyone here famliar with genetic algoritem code
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what did I do wrong here?
question a
also sorry for the small writing
I think it got messed up
Ill redo it
hhere you go
don't chit-chat here pls
this is a help channel
#discussion if you want to chat
oh ok
@hoary seal Has your question been resolved?
@hoary seal Has your question been resolved?
<@&286206848099549185>
I mean this ^
everythings correct @hoary seal
there are issues with the term in sqaure root
it wont b such a low value
its ok ill come back to it
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I am by no means a math person, I have just taken an interest in Python and wanted a rabbit hole to follow for a bit, so excuse me if this is obvious to you experienced folks.
First, I calculated all of the primes up to a million.
Then, I calculated all of the primes with a prime digital sum.
Then, I calculated all of the primes with a prime digital sum that have a digital root of 2.
I took those and assigned them to a point cloud for a 100x100x100 cube.
When viewing the cube from a certain angle all of the points seem to only appear within certain bands. I counted 31 of them, which is a prime number.
I did the same process with dr =5 which yielded 29 bands, which is also prime.
Then again with dr=7 which yielded 17 bands, which is also prime.
Anyone know why this is?
I would expect this to be only coincidence
if your cube was bigger then the number of bands would also change and it seems unlikely that it would be a prime again every time
and also, dont know if you just havent hit the perfect angle for your screenshot, but saying that for dr=5 the upper right region consists of bands is also a bit of stretch
I have to pan the camera to see all of the bands individually, just a constraint of a static camera. Pic was mainly just to show what I meant by bands.
But essentially, I gather it's just a coincidence brought about by the 1 million number constraint.
that the number of bands is prime, yes
that there are bands, probably no
I dont know how precisely you filled the numbers into the cube but I could easily imagine that as a consequence of that some of those slices just for example only contain even numbers
If I scaled it to 1000x1000x1000 and it still produced prime # of bands would it not be coincidence anymore?
well powers of 10 are special given that the digital root is essentially working mod 9 so maybe for powers of 10 I could imagine some kind of result along those lines
but ehh I still wouldnt expect it to be primes
fundamentally almost all small odd numbers are primes so there are a lot of coincidences
its the strong law of small numbers
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,rccw
I don't know where to start
13th
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Hi
Anyone studying trig and can help me
just ask 
Where are the function sinx cosx present in an triangle?
Can you help in visualisation
well the most basic definition of the trig ratios in a right triangle
is sin x = opp/hyp
cos x = adj/hyp
tan x = opp/adj
Yes but are they angles or just ratios of the sides
so sinx means?
the length opposite the angle divided by the length of the hypotenuse
opposite/ hyp × angle?
Oh thank you so much
Can also tell me how trig is used in making of bridges and real life etc
@junior raven
Ok thanks ig
Which grade you're in in?
@junior raven
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is 0 a part of natural number in discrete mathematics?
could you please elaborate on this
in discrete mathematics, it is yes, right?
It depends on the convention
As was said
probably, its a good idea to check with your professor/teacher
logicians and set theorists tend to consider it natural
number theorists tend to not consider it natural
other types of math, i havent seen a strong tendency one way or the other
not sure about that
not sure how to prove one wya or the other without doing a survey of enough texts to show you it's more than 50%, so, shrug emoji
maybe im wrong
shrug indeed
I'll look for conventions and ask my professor
usually from what ive seen 0 isnt
if you want to use something agreed upon, you can use $\bZ_+$ or $\bZ_{\geq 0}$ or $\bN_+$
ExpertEsquieESQUIE
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hi
ime memorisation in math is TERRIBLE
you should always try to UNDERSTAND things and not memorise them
that way, you can just derive whatever you need
I agree you
but I have ten hr before my emags exam
gg you are toast

or maybe if you have the time in exam you can derive it from
x = p sin phi cos theta
y = p sin phi sin theta
z = p cos phi
which is a lot easier to remember
toast do you need a jacobian
I dont think I'll need that
damn
are we cooked together ?
hopefully you are not cooked as me
(yes idk how to construct the jacobian of turning xyz into some arbitrary uvw)
dw we'll survive ig 
I will look into it
thank you
alr thank you everyone
imma close this
.close
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"Prove that at a party where there are at least two people, there are two people who know the same number of other people there."
i know i will use pigeonhole but thats about the extent ive gotten
lol

Look at how many people are known by each person
say that there are 5 people A, B, C, D, E. How many ppl could each of them know?
nice, ill give u some time to try and fiure out the rest
if u need another hint, just ask
alrightt
would reasoning it out as something like
"if there is n amount of people one person could know a max of n-1 people therefore by pigeonhole... n/n-1 = 1 at the least" be enough
I see you wrote 5 numbers here, which is n
why is it n-1 here?
I thought of n-1 as the number of people you can know
yes, which isnt enough to conclude anything with pigeonhole
imagine a party with 5 people A, B, C, D, E:
what if A knows 4 people, B knows 3, C knows 2, D knows 1, E knows 0
direct application of pigeonhole doesnt lead anywhere as you can see
5 pigeons (the people)
5 holes (the n.o. people they could know, that is either 0, 1, 2, 3 or 4)
but also wouldnt people know eachother? otherwise the question is wrong right
wdym by "wouldnt people know each other"?
like if A knows B we assume B also knows A
this wouldnt happen
exactly
and that's what's missing in your reasoning
you need to analyze this special case
hmmm
there are 5 pigeons and 5 holes. But the case where every hole is taken cant happen
there could be a party where
A knows 3
B knows 2
C knows 2
D knows 1
E knows 0
and there could be a party where
A knows 4
B knows 3
C knows 2
D knows 2
E knows 1
but there cant be a party where
A knows 4
B knows 3
C knows 2
D knows 1
E knows 0
it all makes sense on a smaller scale
so the set of holes actually changes, but there are at most 4 of them. There cant be 5 holes
but how do I reason that out as a general case...
alright, so now onto the general case.
What I'd do is say that there are n people and introduce some kind of variable k_j, where k_i is how many ppl does the ith person know. Then we know that each k_i must go in some of these n holes: {0, 1, 2, ..., n-1}
and note that this isnt yet enough to apply the PHP
there re n pigeons (ppl) and n holes
now either the pigeons go into one hole twice (and the proof is done), or in the other case, the pigeons will go into 1 hole each
so every hole will be taken
i.e. youll have a person knowing nobody and a person knowing everybody
as you said, that's impossible
so you can cross out this case and you're done
ok let me digest it lol
oohhh okay i get it
thanks a lot it all makes sense 😭
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How would I do this?
this is a practice test im reviewing in order to prepare for my actual test
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
draw a venn diagram
do you know what that is?
doing that right now one min
ok
agreed
ok, I was right
so, when it says "77 like snickers", you've put down "77 like ONLY snickers"
the sum of this shaded region should equal 77, because these are all the cases where someone would like snickers
okay
I'll give you a hint: there's only one way someone would like all three kinds of chocolate
so you've got that inner 44 right
yep id use it subtract?
yep 🙂
from the 77 and that equals only people that like snickers?\
remember, there are 4 regions there that must add up to 77. so maybe we can do something smaller next?
when it says "46 like snickers or twix", which regions is that referring to?
region in between snickers and twix
wait Or
the Snickers/Twix region
so 100,77 dont make sense
yep
The blue region corresponds to "likes snickers and twix"
The green region corresponds to "ONLY likes snickers and twix"
because, if they "like snickers and twix", they might also like reeces cups.
okay I see
so if 46 like snickers and twix, how many like ONLY snickers and twix?
2
yes
keep going 🙂
sorry, had to dip for a second
we know 77 people like snickers. so, the total for everyone in the "likes snickers" circle (the red bit) should be 77.
19 reese and 41 twix
how many people don't like snickers or twix or cups?
ah the outside
add them all subtract by 500?
yep
yep
yes
now the next bit. which regions correspond to "likes reeces cups, and likes snickers, and doesn't like twix"
27 +4+19?
nope, because they also like twix and we only count people who like snickers and reeces cups, but not twix
everyone in the red region likes twix, so we don't count them.
yes agreed
Could we do another one?
so i can fully master this concept
or ill do it and if i get stuck ill ask you
nvm ty
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I know a little of what the signs mean but i dont know how to do it properly.
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guys i need your help im doing quadratic equations with absolute brackets and i just cant figure out what to do after i make the line with intervals
can you show the problem you are working on, as well your progress
,rccw
i got stuck here but lets say i only know how to do the left half
i suppose the right side implies you are looking for the roots
ok so you computed them, so what you can do is see if they are in the domain (-oo,-5) inside
now for the [-5,3) interval, it implies that x+5>=0 because of x>=-5
so x-3<0 which gives x<3, so you only add a minus to the x-3 term
i just dont know what to do with the equation after the intervals bcs how does 2x*|x-3| become -2x(x+3)
because in [-5,3) you must have x+3<0
you get that way x<3 which fits the interval
[-5,3) is the overlap between x+5>=0 and x-3<0
and do i need to find the overlap or i avoid it
but when i solve both quadratic equations what do i look for
now u just need to realize that since x-3<0 in that interval, you get |x-3|=-(x-3)
ooooohhh
you look for solutions within the domain you are currently in
so it would be 2x*(-(x-3)+(x+5)=0
yes
for the [-5,3)
and the other inteval you have both expressions being positive
so when i do it within its own interval i just put a minus infront?
in the first one the +(x+5) turned to -(x+5)
you ever put a minus in front of a term, when it would be negative
yes, because you are in (-oo,-5) which is literally x<-5
equivalently x+5<0
so |x+5|=-(x+5)
but then why did i put a minus infron of 2x(x-3)
it's an overlap again between x<3 and x<-5
and that overlap is just x<-5 but we still have x-3<0
there may be a language gap yk but let me show you what im talking about
just a sec
why did i put the minus infront of the 2x if its not in the starting equation
well i cant really tell what your thoughts were but what i can say is that 2x|x-3|=2x(-(x-3))=-2x(x-3)
oooh because its 2x(x-3) and bcs its under its own inteval i put a minus infront
we are on the same page i believe
so the main thing is
when i do the absolute brackets under their own interval i just put a minus infront of them
and thats it
thats now what i wanna give away
you should check if the term inside the absolute brackets is positive or negative in your current domain
in the interval of (-oo,-5) we must have x-3<0 because x-3>0 would lead to no overlap at all with x+5<0
so the equation for the interval on the right would be 2x(x+3)+(x+5)
and i solve that to find the quadratic equation
a b and c
you mean for the 3rd case?
you have - -, - + and + +
so for the ++ case you have this = 0
indeed
since x+3>=0 and x+5>=0
and i just dont put minuses infront of the brackets for that one?
yes because both expressions are now positive in the domain [+3,oo)
if you still put a minus, you would make the positive terms negative, which would defeat the purpose of the absolute values
mhm
so lets revise
the first one has a minus infront of the first absolute bracket
the second infront of the second
and third doesnt have any
the first one has two minuses
yes
💡
and i try to find x that fits the interval under each one
and thats the point of the whole thing
you are trying to find solutions of x within your current domain, yea
bro
you were really helpful ngl
i got a f on this in my math class
tomorrow i gotta do something about it
tomorrow you are gonna ace it
believe in yourself
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Can anyone help me out? I don’t think if (log base 2 of x)^2 is the same as log base 2 of x^2…what am I suppose to do instead? Thanks
log2(512)=9
so (log2(x))^2 = 9
if you let y = log2(x) then y^2 = 9, which should be easier to see how to solve
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what did I do wrong in question c?
You don't want T_n to be 945
You want S_n to be 945
He has 945 cabbages in total
Not in the last row
also I am not sure with q b as well, I got fraction again
how did u figure that out?
b is correct.
damn I thought I would get it wrong
"The farmer plants only 945 cabbages."
notice no mentions of rows.
yea but the question is asking for rows, I am not calculating the final answer because I already subbed that value in
i am solving for n, which is the number of rows
but you're solving for n using T_n, which is the nth row to contain 945 cabbages.
you don't want the nth row to have 945 cabbages. you want to find the nth row such that, when totaled up with the rest, you will get 945 cabbages.
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Hi, Im studying prob and stats for a math exam, Im really struggling with combinatorics and understanding how to use it. Im understanding basic permutations now but once it gets a little more complicated i get lost. heres the type of program that really trips me up, I know theres a total of 11!/(3!2!) possibilities for question 2.6.38 but no idea how to do the math for only when LLL is infront of the other consonants. any insight would be appreciated
<@&286206848099549185> ^
Im not looking for an answer as ive found the answer, i just need help wrapping my head around the why
dam no one
LLL S U M G U I O N
LLL S U U M G I O N
(8! ways to rearrange the non-L letters) / (2 ways the Us can be swapped)
,calc 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 / 2
Result:
20160
I know the answer, just dont know why, And yes the L's must come first
I struggle with the letter based arrangement permutations
L L L S U M G U I O N
U U I O L L L S M G N
think about placing the letters one at a time
L L L first,
then 4! ways to place S M G N after it
L L L S M G N
then after that, U, U, I, and O can be placed in anywhere in between
theres 8 places to place an O:
L L L O S M G N
then 9 places to place an I:
L L I L O S M G N
then after that, 10 * 11 / 2 ways to place 2 Us
U L U I L O S M G N
so in all its 4! * 8 * 9 * 10 * 11 / 2
,calc 4 * 3 * 2 * 1 * 8 * 9 * 10 * 11 / 2
Result:
95040
does this line up
what trips me up right
is that just shows LLL first, like how does that math account for something like UUIOLLLMGNS or LLLMGNSUUIO
you gotta confirm whether this matches the answer in the book or not before we can continue
like i dont see how placing the L's first, then arranging the smgn after accounts for all the possibilities
it does
the trick I used is to treat the letters as being placed one at a time
you can imagine that if we typed 3 Ls, then typed the consonants S, M, G, N after it, that would always guarantee the Ls are before the consonants
and whyd ya do 10*11/2,
try thinking about it slowly
if I explain it then youll never be able to come up with it yourself
wait is that vowel part (11C2)?
yes, thats one way to view it
well for the U's right
yes
and also because theres no condition on the Us
just as theres no conditions for the I or the O
so all 11C2 combinations are possible
so they can be placed anywhere
yep
and the slots increase as letters get placed cause now you can place a letter on either side
so i understand the LLL and the 4! part, the letter placements at the end was what was tripping me up ig,
more specifically its that that would make the problem easier
