#help-43
1 messages · Page 68 of 1
so now ? <= t <= ?
a - b <= t <= a + b
Yes
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whyd I get this wrong
7/2...?
is (6+8)/2 = 7/2
is 6 + 8 equal to 7
idk how I got that
how many hours did you sleep last night
6-7
i got 4 😎

rehearsing for ur movie 🙄
so do you see what went wrong now?
any more questions?
-# vroomvroom
is this the full thing?
there seems to be a ratio between the distances that we dont know.
yeah I'm not sure what to do
good luck!
thanks
@modest egret do u know what to do?
no i didnt
External
i saw this a few moments ago
whats the bst approach to this
Yeah this is internal section formulae
but internal section formula woudnt let us calc this right
what are the four diagrams
He needs to match it
oh you have match an option which looks like the diagram
I think it's an incomplete question? Else he needs to substitute each and everything to get the answer maybe
its like the midpoint except
its scaled
I think
affine combinations is when the scalars add up to 1
oh
so in the 3rd Diagram X is between A and B , so both the coefficients should be positive
I dont get it
Can u share the whole picture
the first one is incorrect , you can see B is closer to X so
AX/XB <-1
the coefficients are 4/3 , -1/3 so you can deduce m and n from here
m-n = 3
view hint
ohh
ik how to do this
but
were not given the coordinates
for the position vectors
we are not but from options you can match ratios of AX/AB and BX/AB with options
like assume it?
yeah if Ato X is big then assume its the bigger ratio
else we cant do this they just want to match the diagrams which likely represent the option
so no calculation here?
no idts
what does it mean for two vectors to be colinear?
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I need help with this
it means the points lie in the same line
you could cheese the problem by computing 6 2x2 determinants
it's not terribly mathematically sound but it is a pretty funny idea
There are 6 ways to choose two of those vectors
If you choose two of them and put them as the columns of a determinant and set the third column to be 1 0 0 then you can use that determinant to figure out whether the two vectors lie on the same line
that works because just by visual inspection 1 0 0 is "almost guaranteed" to not affect linear independence
but of course in general that may not be true which is why this is a cheesy method
you can maybe even get away with computing less than 6 determinants
because for each determinant that you get 0 you know that the two vectors are collinear
so if you find two zeroes then you might already be able to figure out which vector is not collinear just because being collinear is a transitive, symmetric and reflexive property
And after you suspect which vector is not collinear with the others, you can try to find the proper justification
this method, however, is kind of stupid. So I propose a second method
The second method is that if Azure and Ivory are collinear, then Ivory gets transformed to Azure after you scale it by 240/255
why cant we use uhm the
And then you can just check whether or not that is true
The scalar multiple method probably corresponds to what I called my second method
it is highly advisable to use that one instead
do we do for each combination of pairs?
its ok Ill come back to it
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int of x^2/x-1 dx
what have u tried
i did long division
integration by parts
dont think thats right
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np
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35
What have you tried
Try multiplying the numerator and denominator by e^x
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triangle ACB and DEB are not similar triangles since <EDB is 90 degrees while CAB is 120 degrees so I can't just use a scale factor...
DE = 16 cm ( as mentioned )
and DB = AB/2 = 24/2 = 12
Since DEB is a right triangle.. I used the Pythagoras Theorem
to get EB which is the root of 12^2 + 16^2..
so EB = 20.. idk what to do from then on
You know the cosine rule?
yes, but I don't think I have to use a trigonometric ratio since this is a 7th grade problem.. + it's a no-calculator exam
cos 120 can be evaluated without a calculator
but it's a 7th grade problem...
You can find the length of CB using the cosine rule BE using the pythagorean theorem. Finally you get:
CE = CB − BE
he wants a solution that avoids cosine rule though
Yeah I can’t think of any other solutions that don’t use trig. The figure kinda sucks lol and I don’t think there are any other special angles to exploit
damn...
What have you learned in your class?
uh... math?
Be more specific. Of course you learned math, but what math
Like, probability won’t help here lol
this is not a school-related problem but rather some math olympiad my mom dragged me into.. but.. ig probability... histograms. line graphs.. prisms and other secondary 1 lv stuff.. def not trigonometric ratios
Oh.
If it’s a math olympiad, then trig is fair play. 🙂
I had a feeling that trig was the only solution. Yeah, it’s going to be the expected solution
Here’s the law of cosines: $CB^2=CA^2+AB^2-2\cdot CA\cdot AB\cdot\cos(\angle CAB)$
I’ll give it to you since you don’t know it. It’s a generalized version of the Pythagorean Theorem
CST (reply ping for help)
Well.... I guess I'll just have to pray something like that doesn't show up on the exam day
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✅ Original question: #help-43 message
Extend AB past A to a point H such that CH is perpendicular to BH
and then it's standard 30-60-90 and pythagorean theorem
no cosine stuff required
It’s not 30-60-90
triangle ACH is
Because BDE is a scaled 3-4-5 triangle
ik
that's relevant as well
since CE=BC-BE
you use BDE to find BE
and BC comes from the aforementioned construction (||BCH is a right triangle||)
me go draw 👍
ok
like dis?
mhm
what do I do next..
I’m walking rn, but read what I said above
Preferably not all at once though
Because that is the entire solution
PS I tried to do this and the side ratios are inconsistent when they should be consistent in principle
Thinking about it more, I think the figure is actually not geometrically possible
Gemini said the same thing too
welp... ig thx for the help
I modeled it to scale on Geogebra
The point names may be different
But basically BA is the perp. bisector of CD
BA is 16 and CE is 12, both at 90° angles
But in the problem the angle is 120°, so it’s even further back
So it opens outwards and it doesn’t close
oh
Now I’m not saying CSP’s approach is wrong. If the figure were actually geometrically possible, it should work
Nothing wrong with his idea in theory
It’s just that the problem sucks so whether you use Law of Cosines or similar triangles gives you different answers
the exam constructors had one job 💔
no way they messed up on an official exam paper
ah...
if that happens to me on the actual exam, im cooked 😭
Ima headout now, since it's 5:16 AM
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Please anyone help me to do this
<@&286206848099549185>
math
how to apply pnc here
answer is 6 here
pls anyone help to solve this SAMO Question
so <5000 and sum of the number is divisible by 9
and tens digit can only be from 1-9 and hundered's digit can be from 0-8
note all the properties first, a+b+c+d=9, 18, 27, but not 36 because 9999 has b=c, a__>__5, b=c-1, with that you can do diff setups for 9, 18, and 27,
mmh more accurate
oh ye that too
lowk wasn't thinking abt that
I have tried this
but my answer is > 6
what does it mean by unique anyways
can you pls check if the answer given is correct or not?
just by looking I'm pretty sure the answer is way more than 6
oh even
even number wait
d is either 0 2 4 6 8, I'm pretty sure you can just count this manually
but my answer is >6
5 - - 0
try to 0 1 ; 1 2 ; 2 3 ; like this and see if which is divisible by 9
and then
i think its not hard
5 6 7 8 9, and 0 2 4 6 8
for which of these when subtracted from 9, 18, or 27 are odd(and less than 20) should get what you can get
can you guys pls check if the answer is >6 or not??
mmh
my answer is >6
5670
5562
5454
5346
5238
6120
7560(repeat)
9450
I don't think it's 6 unless it's asking for combinations w/ unique digits
I didn't enumerate all of them
so answer is>6 right?
wait
i think i know why its 6
its asking for numbers when digits are different
then it will be 6
unique digits, yeah
mmh
but unique locker combinations means different locker combinations right
It didn't say different digits na
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Anyone pls solve this
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
4
<@&286206848099549185>
If you want your work checked, you'll need to post your work
also don't ping helpers before 15minutes, esp if there's already one here ready to assist you
@worn wyvern Has your question been resolved?
@worn wyvern you need to post what you have tried so far if you want someone to help you.
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Renato
Renato
can I get some help understanding example 3.1.5 and 3.1.6
the example entirely for 3.1.5 and 3.1.6
I want to understand the definition of convergence of sequences and both examples are using it
Are you familiar with limits by any chance
@strange pendant Has your question been resolved?
People can only write the definition in other words, which may or may not cause you to understand something. But you need to ask a specific question fr
I am trying to understand the examples
I never asked for help with the definition
I mean I did, but like, I am more focused on the examples that use the definition
because, if I can understand the examples then I can understand the definition at least intuitively
I do understand the definition tho
at least somewhat
how is it being used in the examples can u help with that?
You are given an epsilon from outside, and your job is to find a suitable n0(eps)
you mean n0
do you mind we go through the examples
yes
Ask your questions
I dont understand the examples
You have (1/2)^n
that converges to what?
What do you think it converges to?
n -> infty that converges to zero
If you don't know that, forget eps/delta proof
Good
So you are trying to find an n0(eps), so that when you assume n>=n0, you want to conclude |(1/2)^n-0|<eps
If you have an implication A => B, then you assume A and try to conclude B from that, but the issue here is we need to first prepare A, by finding n0
(1/2)^n = 1/(2^n)
|(1/2)^n-0| = |1/(2^n)| = 1/(2^n)
so what I want is that 1/(2^n) < e right
so 1/e < 2^n and so log(1/e) < n.log(2)
Ok seems you are a bit skippy, but yes, you wanna do some scratch work
We are working backwards
then it follows -log(e)/log(2) < n
help me please
What am I doing right now??
we might need to use arquimidean property, that forall x in R there exists some n in N such that n > x
n >= n0 <==> 2^n >= 2^(n0) <==> 1/(2^n) <= 1/(2^(n0))
|(1/2)^n-0| = |1/(2^n)| = 1/(2^n) <= 1/(2^(n0))
I mean ya, if you are rigorous about it
Yeah
I still don't see a question
Like you come
say entirely but you already do know stuff
the hardest part is always finding n0 for the epsilon they give us
help
Are you ragebaiting
use archimedean principle to show that for all positive epsilon there exists natural n s.t 1/n < epsilon
Do you understand why tho
Intuitively
is 2^(n0) not an natural number
right, my bad
I am trying to understand
this is why I am asking for help
I am trying to understand how to use the definition for convergence of a sequence on the example sequences
You are literally using it rn
If and only if we don't give up while suffering
i can show you in vc @strange pendant
which vc?
its trivial
Cyrenux 🟨 when
wait, my pc is freezing
At what point you are?
I am doing the first example
have you already written something?
@rapid crescent
you have to show that 1/2^n <= epsilon
log(2^n0) is n0
didn't you take the base 2 logarithm of both sides?
I think its just log_10
log base 2 is lwk cooler
so for n>n0 you can set n0 to approximately that quantity, in fact you have demonstrated that for every epsilon there exists an index n0 such that the definition is respected
you proved that the limit is 0
no i did not
so what did you do?
I was trying to find an n0 such that 1/(2^(n0)) < epsilon
yes
so for n>n0
for every epsilon >0
have you found an n0 such that for n>=n0 1/2^n <epsilon?
so that when all the epsilons vary, does this n0 exist such that the definition is respected?
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).
@strange pendant Has your question been resolved?
@strange pendant vc?
why
He wants to play mc with you
you must prove
I cant I am doing anal homework
help please
yes join
but dont play mc dude for the love of god
I cant play mc rn, I am doing anal
I should be done with this exercises this week, and I still have like 15 more exercises to go
and I am also taking like 3 other classes simultaneously so I cant play mc bro
i was helping you while playing wdym, also im not playing rn
bro you are not doing anal
calc*
you are doing analysis
What are you trying to do here?
im trying to proof this goddaym sequence converges to 0 as n -> infty
What sequence?
1/(2^n)
i shee
Yo you know the definition of convergence?
yes dude
I sent it a little while ago
basically forall n in N there exists some n0 in N such that
n >= n0 => |an - L| < epsilon
@mystic field @winged lion @rich flower
Yeah, we know.
How about ration test?
ratio?
I need to use this def isaac
I cant 🥀
You HAVE to?
ye
Take the log base 2 of both sides.
,calc log(1)
Result:
0
log(1) is 0
I get that n0 > -log(epsilon)/log(2)
You can't use calculus in real analysis vro
no vc?
n0 > -log(epsilon)/log(2)
n0 > log(1/epsilon)/log(2)
n0 > log(1/ epsilon - 2)
So, what exactly is your problem?
Just pick an N such that n>N and formalise the proof.
Preferably ceil(log_2(1/epsilon))
To get 1/2^n < epsilon
as n approches +infinity,
ceil?
2^n>n does too.
Least integer greater
So, there exists an N in Z such that 2^N > 1/epsilon
So, for any n in R,
there exists N such that n>N a
and 2^n>2^N>1/epsilon.
@strange pendant
Reason being that if it were log_2(1/epsilon) the condition would still hold but N has to be a natural number so we set it to be the least integer greater than that for the condition to still hold.
@strange pendant
@strange pendant
Hello?
@strange pendant
yes
Did you see what I sent you?
n>N
n0 = N?
blud really pinged OP 4 times in 8 minutes
HAHAHAHAHAHAHAHAHAHAHAHAHA
What?
Karma 
Indeed, anything else?
MAYBE A MATH COMP PROBLEM OR TWO??????????
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i know its not exactly math but i have some kind of competition where i need to write proofs can you give me some advice to study
its not exactly maths
I have to write proofs
what do you think it is then
What math competition? I'm ok at those.
i mean its not a math question like if i ask u how much is 1+1
olympiad dsmc
Have you heard of AoPs?
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,calc log(100)
Result:
4.6051701859881
.close
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for this question i simplified the square root into $\sqrt{x^2 (x^2 + 2x)}$
g
and then i simplified it further by x$\sqrt{x^2(1 + \frac{2}{x})}$
g
am i allowed to do that
yes
i'm kinda confused on this operation because can't i just repeat this process and get infinitely many x^2 out of the square root?
and that just wouldn't make sense
You really only need to take $x^2$ out, since then you have $x^2 - x^2(\text{something})$ in the denominator
Azyrashacorki
It would probably help to multiply and divide by the conjugate in this case.
yes, but i just feel like this just wouldn't make sense if i can just take out another x^2 out of 1 + 2/x, and make it something like 1/x^2 + 2/x^3
and repeat to take out infinitely many x^2
Yes of course but the expression you would get wouldn't help.
I know for this question i don't need to do that, but this is kinda confusing me
The usual goal here is that you want to force a factor of the highest degree present in the denominator and numerator.
One can alternatively also use the binomial expansion for (1+x)^n for small x
The fact that you can do it doesn't mean that it's helpful is my point. There's nothing wrong with it but now you end up with a form that's even more indeterminate than it was
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since it says leaf unit 0.01, is the first observatiuon 19.01, or 1.901?
my prof says 19 | 5 = 1.95 but is it 19.5 instead?
@round pier Has your question been resolved?
@round pier Has your question been resolved?
"A leaf unit of 0.01" means that the leaf digit represents the hundredths place. So to find the value, you combine the stem and the leaf and multiply the leaf unit (which is precisely what was done to obtain $195 \cdot 0.01=1.95$). As a sanity check, you have a 2 litre container, so an answer of $19.5$ is ridiculously large.
Civil Service Pigeon
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<@&268886789983436800> look at this 💀
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Like this?
what angle do you need
just googled one: https://www.geogebra.org/m/t76ctzgb
put a paper over the screen on the left then sketch out the net
np
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Good morning/good afternoon everyone, could someone help me with statistics? I'm in the 4th year of secondary school.
I wanted to understand how to draw the graphs.
try one of the channels in the Available category, like #help-14
also it would be helpful if you had a specific problem to work off
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If I just compare the height and say that by observing since the equation has a linear part and a func part, I will try u= ln (tan(u^bar/2)) and then check for it(which turns right), would that be a solid proof, or should I do the more methodical method of equaling for r and clear the equation
@modern totem Has your question been resolved?
Seems fine to me
your "methodical method" is a way to find the substitution, but the crux of the proof is showing that the subsittution actually works
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hi
for this question, how can we use the curl test to dictate that the field is conservative because the region is not simply closed right?
so the second choice is iffy right
or is it a simply closed region
well the curl is only defined for three dimensions, not two, so you'll want a different test to see if it's conservative. (hint: directly related to the potential function)
moreover these tests dont depend on the region of integration being closed, all that's required is that the vector field is defined over an open, simply connected subset of R^2
you can sketch the region or desmos it to see if it's closed
that's true actually with the 3d
but we can just assume this form <x, y, 0>
Remember that theres scalar curl
i see so it's
i guess the region of the field
region of integration is for greens thorem
what's that
i mean yeah, which gives you $\pdv{F_2}{x} = \pdv{F_1}{y}$ iff the field is conservative
haseeb ♥
For $F(x,y) = \langle f, g\rangle$, the scalar curl (equivalent to curl for flat 2d regions) is $\frac{\partial g}{\partial x} - \frac{\partial f}{\partial y}$
i,j,k
Its just the divergence of the 90º degree rotated field.
So instead of outness you measure "rotativeness"
regardless of how you curl your fields, is F conservative?
yeah it is then
if the field is defined on R^2
R^2 is simply connected
we'll consider it to be defined and smooth on R^2 since why wouldn't it be
then can you find a potential function for F?
yeah
integrate with respect to x for the x component for the field
then with y for the y component
the constant you get out is a function of y and x respectively
and then are there any stipulations that forbid us from using the fundamental theorem of vector calculus?
no
so you just integrate with the f(B) - f(A)
i mean
you just do f(B) - f(A)
with B being the point and A being the other point
thank you I just wanted to know about the curl test really
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yeah exactly :)
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How would I do this?
the limits exist for all monomials
which is x^k
By linearity, they exist as polynomials.
wait are you claiming that the lim 1/n sum x^k always exists?
No, The problem assumes that for this particular sequence
that the limit 1/n sum x^k exists
using that assumption, we prove the limit exists for every continuous f
so we can say monomial is there but not proved
I hope it helps :)
Yeah, i get your point now 
@placid oak you want anything more?
ah we say it exists for all polynomials
and then argue that because every continuous function can be approximated by a polynomial, the image continuous functions at those x values exist
yeah
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ok please can I get some help with this exercise
I kind of understand but at the same time I dont
the idea is for example, if a) is a definition of primality, then
a) holds for p <=> p is prime
so what I have been doing so far is that, I pick random values for p (both prime numbers and composite numbers) and try to see if a) holds when p is prime and if it doesnt hold if p is composite
after this, I get a general idea of whether a) is a possible definition or not (if for example I try many p primes that make a) be true aswell as if I try many composite p that make a) be false)
after this, I get a general idea of whether a) is a definition of primality, suppose every p i try if it is prime it makes a) be true and if p is composite then a) be false, after all this p I try then I would like to prove this a) is a definition of prime number, so I would like to prove
a) <=> p is prime
the left direction <= is simple, suppose p is prime then d | p means d is 1 or d is p, but since d < p then d = 1, so if p is prime a) holds
what I am struggling with is the right direction =>
that is,
a) holds for p => p is prime
same for the other letters from a to e
can I get some help with this? the exercise is asking that after seeing this predicates I see if its a definition of prime number > 1
For the direction "a) holds for p => p is prime", it's easier to work with the contrapositive and prove "p is not prime => a) does not hold for p".
why
I mean you can argue the other direction as well if you want, but it's just easier with the contrapositive.
why it is easier I ask
can you elaborate
I just feel like it is. In any case if you were doing "a) holds for p => p is prime" directly, the easiest argument would be contradiction.
Because you want to show that p has no divisors but 1 and itself. Unless you want to test every number to see if it's a divisor less than p, it's easier to show that such a divisor can't exist.
So it would all boil down to the contrapositive anyway
but in the case of a) it is a def, so no counterexample exists correct?
@thick comet
how to prove it tho
The contrapositive is an equivalent statement. It's not a counterexample.
"p is not prime => a) does not hold for p"
- What does it mean that p is not prime?
- Once you've defined it explicitly, then why can't it satisfy a)?
p => q and the contrapositive is not q => p
The contrapositive is not q => not p.
i see, this is very useful
but I dont understand suppose P is p is prime and Q is a) holds then by countrapositibe logic if a) does not hold then p is not prime
@thick comet
This should make sense. If you want to show that a) describes primes, and only primes, it suffices to show that :
- primes satisfy a) (i.e. p is prime => p satisfies a)) -> this means that a) describes primes
- composites don't satisfy a) (i.e. p is not prime => p does not satisfy a)). -> this means that a) describes only primes, no other numbers.
This would be the contrapositive for the statement "p is prime => a) holds for p". You've already proven this statement directly.
Answer those
p is not prime => not a)
there exists some d | p such that d =/= 1 and d =/= p
the cardinality of the positive divisors of p is greater than 2
unsure
d < p and d | p forall d in N => d = 1
Well use the first one. If there is some divisor of p which is neither 1 nor p, does a) hold?
F -> F
Say this divisor is d.
Is d > 1? Does d | p? Is d=1?
i told you if p is composite then there exists some d in N such that 1 < d < p such that d | p
Okay, so does a) hold or not?
it does hold yes
Why?
F => F is true.
the d < p and d | p dude
Okay sure. Is d < p? Does d | p?
right, mb so d < p and d | p holds so T => F is false as fk
So then a) does not hold.

...
You've shown that if p is not prime, then a) doesn't hold for p.
So you've shown that if a) holds for p, then p is prime.
p is prime <=> a)
i proved already
p is prime => a)
i want to prove a) => p is prime
And you haave
that is
p is not prime => not a)
i see, so we just proved the left direction
we are done then
p = 2
d > 1 and d | 2 => d = 2 => 4 does not divide 2
p = 3
d > 1 and d | 3 => d = 3 => 9 does not divide 3
p = 4
d > 1 and d | 4 => d in {2,4}
d = 2 => 4 | 4
d = 4 => 16 does not divide 4
b) <=> p is prime
You'll notice that for primes the argument is pretty much always the same.
You've only tried 1 composite though.
this shit is confusing though
try 6
right?
We've already gone through this if you just try the first two composites you'll find it.
p = 5
d > 1 and d | 5 => d = 5 => 25 does not divide 5
5 is not a composite.
You don't need to try every number. The fact that you've argued the same way for each prime so far should give you a hint that primes satisfy b).
The issue is composites.
p = 6
d > 1 and d | 6 => d in {2,3,6}
d = 2 => 4 does not divide 6
d = 3 => 9 does not divide 6
d = 6 => 36 does not divide 6
i dont understand anything
I want to prove that
p is prime <=> b) holds
If 6 satisfies b), can b) be a definition of prime numbers?
for primes p, b) holds everytime
something related to the contrapositive
I cant figure it out
p is prime => b) holds is proved
Well it's pretty clear that "p is prime => b) holds for p" is true yes.
suppose b) => p is prime
then p is not prime => b does not hold
but I found p = 6, such that b holds
T => F indicated contradiction
p = 2
d | 2 => d in {1,2}
gcd(1,2) = gcd(1,0) = 1
gcd(2,2) = gcd(2,0) = 2
p is prime <=> c) holds
p is prime then d in {1,p}
gcd(1,p) = gcd(1,0) = 1
gcd(p,p) = gcd(p,0) = p
@thick comet
suppose p is prime then c) does not hold
because T => F is contradiction
Yes, in this case no prime satisfies c). You could have just stopped at your computation for p=2.
help with d)
@thick comet
Have you tried some numbers? What have you decided on proving?
i dont know how to do it
d) is hard
@thick comet
Well Euclid's lemma states the direction
If p is prime, then d) holds for p.
no
Yes.
no
we didn't covered euclid lemma
we need to prove both directions from scratch
p is prime <=> d) holds
That's fine I'm just stating that Euclid's lemma is that specific direction so you can prove it.
we CANT escape proving the rigjt direction
I never said not to prove Euclid's lemma
can you help
Can you write down in detail what you want to show?
what
.
p is prime then euclids lemma holds
More detail. What does d) say about p?
p is prime then d holds
What does "d) holds for p" mean?
if p is prime then forall a,b in N p divides the preduct of a and b and then p divides a or p divides b
@thick comet
p => q = not p or q
if p is prime then there exists some a,b in N such that p does not divide ab or p divides a or p divides b
You don’t need the contrapositive here.
no
The statement is that if p is prime and p divides a product ab, then p must divide a or b
is not the contrapositive...
Yes nevermind. Although this formulation doesn’t clarify things.
so?
you forgot the forall a,b
no?
is not p divides a product ab, is that p divides every product ab with a,b in N
It’s implicit
The point is that if you have a product ab and p divides it then p must divide a or b
So start with p being prime, assume you have some ab which p divides.
Try to argue that p must divide a or b.
how
Do cases on whether p divides a or not.
If p divides a you’re done.
If p does not divide a, what can you say about gcd(a,p)?
who tf knows at this point
This doesn’t help. Think about the case where p does not divide a and what it entails for gcd(a,p)
Problems in maths exercises aren’t made to be easy, they’re made to make you think.
You’re skipping the thinking part
gcd(a,p) divides both a and divides p
i am not skipping anything
is just that proving euclids lemma is hard
In assuming that you’ll know what to do right away, you are skipping parts of the process
You have to try things.
What can you say about gcd(a,p) if p is prime and p does not divide a?
suppose euclid lemma is true
then the negated predicate should be false
maybe its easier to show that the negated is false
@thick comet
if p does not divide a then a does not have a factor p in his prime factorization, so p and a are coprime
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Use Bezout and think about it.
✅ Original question: #help-43 message
then what?
Then you think. You want b in there on the RHS optimally.
wdym?
Problems in maths exercises aren’t made to be easy, they’re made to make you think.
You’re skipping the thinking part
why
baX + bpY = b
Now you think.
About what you want to show. About what you have assumed and/or have derived. About how those could help you show what you're meant to show.
(ba).X + (bp)Y = b
(ba).X + (bp)Y = 0 (mod p)
b = 0 (mod p) <=> p | b
See? It was only 5 minutes and you found it.
Yes
shit is getting abstract real fast
i mean keeping track of many stuff is hard
The point is that now you know you're able to come up with things on your own if you just think about them for more than 5 seconds.
This isn't calculus anymore. There isn't a nicely drawn path to solve any problem. Unless you learn how to try things and fail you're going to hit a wall very soon called exams. It takes time to solve exercises in mathematics, not because it's long to write a solution, but because it's long to come up with it in the first place.
Each time you ask for help without trying anything, you're missing out on an opportunity to learn.
you are making it seem like a hardship to just study maths
i try to not ask questions without trying stuff
but sometimes I dont know even how to start
If you picked maths as a degree because you thought it would be easy and you'd solve everything in 5 minutes then you're in for a surprise.
Maybe you're not realizing but you do that a lot!
And that's why you try things. If it's been a while and you can't make progress, then you ask for a hint or a head-start and you try more things from there.
It doesn't mean that the hint will give you a clear way to the end, but it gives you some more spaghetti to throw on the wall until it sticks.
who would think dat?
only when I dont know what to try out
I have been days trying to figure out this simple exercise in definining primes but I think after hitting my head against the wall and the explanations u guys gave on the logic behins this I am finally starting to figure it out
like it seems easy but for me it isnt that simple, this is why I have been trying to do this over the week
Just in this conversation, I've given you ways to go forwards like 7 times and for all of them your response was within 5 seconds and it wasn't "I'm going to think about what you just said for a few minutes and try things."
depends
sometimes I think bigger hints would get me less stuck so often
you said, use bezouts!
but also we needed to recall that p | ab and p | px
I said "Use Bezout and think (...) About what you want to show. About what you have assumed and/or have derived. About how those could help you show what you're meant to show. "
This thinking process includes knowing that you assumed p|ab
yes but this is what I was saying out earlier
when you are deep in the casework that p does not divide a you also need to remember the assumptions from the premise, like p | ab and recall basic stuff like p | px forall x in Z
I guess, but is hard, when I barely recalled the bezouts lemma by himself
I had to shuffle my memory for that def
Again, that's part of the thinking process when you're given a hint.
You try to understand what it means and how it may help.
And case in point after a few minutes you made it through!
I am just saying that is not easy by any means and is ok to ask for help when you get stuck
I didn't say that you shouldn't ask for help. I said that if you're given help you should take the time to think about what is being said before asking for more help.
Take the moment I first told you that for a) you may want to use the contrapositive to show the other direction of your proof for instance. That would have been a good time to think about what contrapositive means, about what it would look like in that case, about how you may argue then. If you've done those, have given it an honest attempt and can say where you're stuck, there's no issues asking for help.
Chances are just like with this last one, you would've ended up finding it yourself and learning more in the process.
And then the next time you would be proving something similar to this, you would think back to the time where you were stuck and used the contrapositive of the argument.
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Again this isn't a plead against you asking for help. It comes from a place of concern because you're missing out on so many learning opportunities by assuming stuff will come to you in seconds and giving up suuuuuuper fast. At the risk of repeating myself, it takes time to prove things in maths.
I have been at least trying for a week to figure out this exercise
who said I gave up on it super fast?
no it's not that, sometimes I can't just think of approaches for the exercise, then ask for hints close the channel and try it for myself
Do of it what you will. I'm just telling you that's how it comes across when you ask for help.
this is my first year of university. I am still figuring things out, is not that I give up trying super fast, is just that I am not that creative to be frank
And I totally understand that. First year uni is lots of new abstract concepts, and it involves getting familiar with types of problems that you've not seen before, building up intuition that you don't necessarily have.
My point is about how you approach getting help, which at the end of the day is hindering your progress.
There was some times when I asked for help and nobody helped, I still tried stuffs out and asked classmates and somehow stuff ends up clicking if you keep trying you will understand everything, is just that sometimes I dont even know how to start or am tired of trying things out and I ask for help here and without much context it might seem like I didn't do much, but is not like you guys can comprehend my thinking process just because I ask for questions here sometimes you know, I am also a real person in life
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can someone teach me how to multiply matrices? I keep getting confused on what to multiply and add
do you have a question you were stuck on?
khan academy
go to khan academy, learn the concept and then come back here.
with a doubt in a particular question
or libretext math also works
okay
not really just the concept
oh then yes go look online and come back if you are stuck on a particular question and need help
alr
You “dot” the ith row with the jth column for the i,j th entry
Where the dot product mean you multiply the corresponding entries and the add it all together
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hi
my teacher posted these notes and I’m not sure if the formula is right
and what is the right formula
and is the example she provided correct?
and if wrong how do I do it
can you explain how I got this wrong then
can you show your work
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I just used the teacher formula
can you show your full work
ok as mentioned above teachers formula was wrong
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I tried workin on this with a previous tutor but they weren't able to make much progress.
Are you familiar with geometric series?
I see you've used them on the previous problem
Maybe? But I'm not sure if I'm familiar enough with them for it to matter. I think we were like, trying to find the derivative to get the pattern for the power series representation but I have zero clue how I'm going to find the second derivative or the pattern at all from something as complicated as this.
The reason why I'm bringing it up is that you can rewrite the function so that it looks like a geometric series.
then no, for these purposes
Well since you've used it above I don't see why it wouldn't be used here. It's not particularly intricate.
And there won't be a nice pattern for the derivatives
Well, I did work on that prior problem with another tutor
The only thing you need to do really is to divide the numerator and denominator by 4.
Then you're left with $\frac{x^2}{4} \cdot \frac{1}{1+\frac{x^2}{4}}$. Can you see how you'd write this as a geometric series?
Azyrashacorki
The second factor in particular, $\frac{1}{1+\frac{x^2}{4}}$
Azyrashacorki
Yeah, that is part of the maclarian series x^n, which could work I guess.
hmm, but where would x^2/4 go?
You essentially just need to write this part as $\frac{1}{1+\frac{x^2}{4}}=\frac{1}{1-r}$ for some $r$.
Azyrashacorki
In particular, consider that $\frac{x^2}{4} = - (-\frac{x^2}{4})$
Azyrashacorki
now you've lost me again.
Are you aware that $\frac{1}{1-r} = \sum_{n=0}^\infty r^n$ for $|r|<1$?
Azyrashacorki
yes! I do not know how to rewrite this part
Well if you use the fact that $\frac{x^2}{4} = -\left(-\frac{x^2}{4}\right)$, then $\frac{1}{1+\frac{x^2}{4}} = \frac{1}{1-\left(-\frac{x^2}{4}\right)}$.
Azyrashacorki
Can you see what r is now?
-x^2/4?
Yes
So can you rewrite it as a series using this
This it then for our power series representation?
(bottom left)
Doesn't feel right to me
but if it is, I won't argue
...I guess the silence is supposed to be my answer?
Sorry it’s not loading nor letting me respond on my laptop
ahh, sorry
I didn't know that was actually that big of a problem
now I feel like an asshole lol
You just need to use this with r = -x^2/4
For the factor on the right
No don’t worry about it hahah
Yeah, I did. But wait, is it just sum (-x^2/4), or do I need x/n! and (x-0)^n?
We're going for a full maclarian, right?
Yes exactly. No n! or factor on the right
It gives the same thing as the MacLaurin series yes
Alright, so our power series is sum (-x^2/4)^n?
That's for the factor on the right, you can still multiply it by x^2/4
oh
how do I multiply it then? Just, what, -x^4/8?
or just, since it's already beneath the power of n, just (-x^2/4)^n * x^2/4?
The latter
sounds good! I'm just never sure if I have the answer
So you can like multiply it in and combine exponents and all to get your terms
Now to determine the radius of convergence, you had $r = -\frac{x^2}{4}$ so you can check what condition you need on $x$ so that $|r| < 1$.
Azyrashacorki
I've actually found someone else in meatspace to work on this with. Will come back later when I need more help. thanks!
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Hello, I was hoping to confirm my answers to the following two highlighted questions:
My answers are as follows:
7(c): 14x - 10.
7(d): the orthogonal basis is {1, x, x^2}.
@fluid sparrow Has your question been resolved?
I can confirm d) but c) is hard to confirm without seeing the work
,w (p(0) + p(1) + p(2))/(3) * 1 + (p(0)(-1) + p(2))/(1 + 1) * (x-1) where p(x) = 3x^2 + x - 2
should be 7x - 3
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<@&268886789983436800>
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Thank you again, it is indeed!
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Integrating dx gives you only x
Yeah right
How many solutions of what?
Shouldn't it be a unique solution?
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Please tell me this concept
It's from the existence and uniqueness theorems



