#help-36
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Did my teacher skip on those cuz I’ve only seen him write things from textbook to the board only-
maybe
some teachers don't explain properly
He speaks quietly and just writes the problems from textbook on the board and solve it himself and make us read the rules written on the textbook so I get very sleepy in his classes-
sigh, do Japanese teachers still teach like that....
Had a better strict grandma teacher but she was changed to middle school teacher from my highschool-
This male teacher also always busy and gives us lot of study periods while he handle his jobs outside school-
And when you ask him question he tells us to figure it out ourselves and call it easy
When I told him it’s hard and I can’t understand anything he straight up gave me weird look and told me it’s easy
And now his wondering why I’m failing his class
Now test is tomorrow and now I’m here struggling to understand anything from textbooks
right, back to the question I guess
Kk
but then the original y-value (sin is y) is negative, but the new y-value is positive
so you have $\sin(7pi/6) = - \sin(pi/6)$
south
I’m having hard time understanding
do you agree that a straight line connects these two points?
so the angle on a straight line is 180 degrees = pi radians
Yeah I guess
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i need help with understanding hinge theorem, and also with this problem😢
@fossil mauve Has your question been resolved?
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$$\left( \sum_{n=0}^{\infty} \frac{1}{n!} \right)^{4 \sum_{k=0}^{\infty} \frac{(-1)^k}{2k+1} , \sqrt{-1}} + \sum_{n=0}^{\infty} \frac{n!}{(n+1)!} = 0
$$
oguz
could someone explain this😭
the sum in the power is pi/4
so the whole power simplifies to i * pi
the sum in the base is a definition for e
yes
right thanks
harmonic series
May I ask a question?
@alpine compass Has your question been resolved?
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I need help with the task below:
We can write $e^x$ as an infinite series called a Taylor polynomial: $$e^x = \sum_{n=0}^{\infty} \frac{x^n}{n!}= 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!} + \frac{x^4}{4!} + ... $$
By including a finite number of terms in the series, we obtain an approximation of $e^x$.
Find the integral $I$ by approximating $e^x$ with a Taylor polynomial with four terms.
dream
Where's the definition of I
$I = \int_{0}^{1}e^x dx$
dream
Then understand how large the error is
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question, how can I the the x value of local min/max and the y value of global max/min
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ill share what i have done
for future reference: starting a message with . PREVENTS channel opening
also did you mean to upload a pic of your question?
yes well takes a bit time since i do not have the app on my phone im sorry
thanks for the info
ok let's wait for the question and your work then
1st try
then some sin cos weirdo just to separate the 1st n second try
the rest of the 2nd try
ح ع ت means indeterminate
yes
half of your x's look like n's. it's a bit disorienting
well ouch sorry its not he first time i get this remark
so... i see you're trying to do it with l'hôpital or something. is that a requirement?
or is that just what you chose
idk whats l'hopital actually
ouh well yeah if it is called like that i thought it has smth to do with solving a limit using derivation
im asking if this is:
A) the method your teacher requires you to do
B) simply the method you chose yourself for this question
C) the only method you know anyway
B) and C)
since i tried all what i knew could help
or thought
ok right
can i suggest an alternative?
it's not going to involve any derivatives at all
should i revise perhaps i have forgotten smth
or its solution acquires a certain other method
i would love to yeah
ok right
i think this will be easiest if i write it on paper cause i kinda don't feel like doing it in LaTeX
so gimme a few mins
ayyy i understand
take ur time :DDDDD
this is only part of the solution bc im not giving out the full one
but this is how i thought to do it
you tried to start off with splitting the fraction too but your split went too far
if you do it how i showed, you can still break off a part that is safe to put x=2 into
and then take care of the other part separately
I'm processing/understanding each step and try to re do it alone to make sure i got it fully
I'm really thankful
you can and should ask me about specific steps if you have doubts
a safe part is the one that gives a real number right?
"safe" in this case means doesn't cause a division by 0
ouh god
the only thing i would ask
how would u know which part from the separated root/sqrt to leave under that frac that is between ()
or ull try to imagine how it would be like later
yeah this looks good
i pulled the 1/sqrt(x+2) to the side bc that's a "safe" factor -- putting x=2 into it will give you 1/2
but you can't substitute x into only part of the function you're taking the limit of
so that just stays there as-is until the rest is ready to have x substituted in
(sqrt(x)+sqrt(2)) is also a safe factor btw. could be pulled aside in a similar way but what you did still has the correct key idea
so yeah you have the correct answer of -1/2 and you captured the process correctly
@tired walrus how did you get so good at math
frrrrr like omg
@tranquil pine Has your question been resolved?
i mean... i have a master's degree in it AND i work as a math teacher.
AND i studied at a relatively prestigious uni in my country of birth
AND i was lucky to have parents who are on good terms with math
so like idk. it's a whole bunch of stars all aligned in my case
@tranquil pine in case you're also interested
Can you solve the reimman conjecture tho /jk
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Can I have help with this question please?
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
3
3
What do you know about $x$ and the frequency density shown by the upper red line
flynger
@elfin fog Has your question been resolved?
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how would i find the horizontal phase shift for this graph?
@heady reef Has your question been resolved?
What step are you on?
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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
i've got the amplitude, period, and the vertical shift
just need the horizontal phase shift
recall that sin(0)=0
and that the amplitude of sin(x) is y=0
where does there exist a similar point on your function (where f(x)=amplitude)
do keep in mind what sin(x) normally looks like
The amplitude for that graph is -1.72
When x = 2.35 y = -1.72
I could use that point
yep :)
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I'm having trouble identifying the sample versus population and it's stressing me out
Technically the pesticides are being tested, not the crops?
population = everyone/every thing
sample = portion of the population
its been a year since i took AP stats
So
that makes it sound like ALL the crops are population
and just the 10 of each of his crops are the sample
I'm just unsure because it's the pesticides being teested
Wait no I'm dumb because you study something on people
Let's see how this turns out.. 😓
omg my assignment isn't tellinhg me what I did wrong/right like it usually does
I'm cooked
Okay thanks nonetheless
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I found y' but don't know what to do next
can you write an expression for the distance from the particle to the origin in terms of x and y (or even just x)?
it'll be convenient to give it a name too, so call it r
So just sqrt[x^2+y^2] ?
Ann
you have that dx/dt = 3
and you want dr/dt when x=4.
Oh ok
do you see how to continue now?
I just plug in x and x' and solve for r' right?
Can you explain how the y turned into x? Wasn't it y=sqrt[x]
$y = \sqrt{x}$ and therefore $y^2 = x$.
Ann
if you wanted me to be more bureaucratic i would have written $$r = \sqrt{x^2 + (\sqrt{x})^2}$$ perhaps.
Ann
your r' is wrong
chain rule misapplied on the root!
also if we're doing time derivatives then might as well write them with over-dots instead of primes
you'll have $$\dot{r} = \frac12 (x^2+x)^{-1/2} (2x+1) \dot{x}$$
Ann
or in more familiar notation
$\dv{r}{t} = \frac{2x+1}{2\sqrt{x^2+x}} \cdot \dv{x}{t}$
Ann
@tall vector do you understand
Yes
Why shouldn't I use chain rule for something like this, but instead distribute
bc if you dont distribute then you have to use both chain AND product
and you used the fool's product rule
also, unrelatedly,
is this (a) $\frac{1}{3}\pi$ or is it (b) $\frac{1}{3\pi}$?
Ann
It's a 🥲
ok well dont fucking write it in such a way that the pi looks like it's in the denom mate
either write $\frac13 \cdot \pi$ or something, or $\frac\pi3$ or just pay 30% more attention to how you place symbols on the page with your pen(cil)
Ann
anyway
(3.25h)^2 * h
if you dont distribute this
youre gonna need the product rule
AND the (...)^2 part will require the chain rule
its gonna be a royal mess
and your life will be difficult and you will question your life choices up to that moment
Okay so basically I should distribute whenever I can and use chain rule/or just take derivative of the variable if everything else is a constant?
i am not going to give you any sort of directive to "distribute under xyz conditions"
but what you SHOULD do is SIMPLIFY your functions BEFORE you take their derivatives, IF such an opportunity presents itself.
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i am blank. How do i start?
let the members of the arithmetic progression be a, a+d, a+2d, a+3d
then
a+2, a+d+7, a+2d+9, a+3d+5
are the original x_i and thus form a GP
it'll take a bit of crunch but you can find a and d from here surely
that or try doing a similar thing but starting from the gp
won't they be
a-2, a+d-7....?
no
i would definitely start from the geometric representation, there's a lot more structure
you subtract 2, 7, 9, 5 FROM the gp to make ap
ig so
maybe it's less ugly that way
yes, it is
so you mean this is the gp
and this is the ap
?
so now my job is to find b and r?
yes
i don't
i got an eqn $br^2 - 2br + b +3=0$
Prathmesh
there are plenty of questions which i skip
you should have two eqs
Prathmesh
great
now we need to solve these for b and r
normally that would be difficult, but these equations are structured very nicely
$r=2$
Prathmesh
yup
$b=-3$
Prathmesh
looks good
now we got the terms
the geometric representation is very handy now
because we want a product of the original terms, which is easy to write in terms of b and r
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✅ Original question: #help-36 message
you should open a new channel instead of reopening this one
First write the general kth term of the sequence
ohhok
also you should tell people if the dot there means * or a period
$\sum_{n=1}^{n=\infty} \frac{n}{n^4+3n^2+4}$
Prathmesh
that was the original doubt'\
how do i factorise it
+n^2 - n^2
$(n^2-n+2)(n^2+n+2)$
DragunSlayar
how did you do that?
DragunSlayar
yea
$(n^2+2)^2-n^2$
DragunSlayar
$a^2-b^2 = (a+b)(a-b)$
DragunSlayar
yea thanks
Np
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What would be nth term?
show some work
@restive sinew Has your question been resolved?
Multiplication
of?
np
A/(n-1)+B/2n+C/(2n+1)
A(2n)(2n+1)+B(2n-1)(2n+1)+C(2n-1)(2n)
So for n=0
B=-1
WHEN N=1/2
A=2
when n=-1/2
C=2
2/(2n-1)-1/2(2n)+2/(2n+1)
!done
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which one of these lines is steeper?
i think this is a problem where my english isnt too good, or something like that. because I have no idea which of these 2 lines is steeper, and everyone around me diminishes this as super simple
but its been giving me a lot of trouble in physics (this question is about isothermal and adiabatic processes in actuality)
left is steeper? maybe show ur original question
the actual question is just physics
at the end of all of that, it comes down to which of the two lines is steeper
well left cuz it goes down more while going to the right less (rise/run)
If this is a language issue, in what language are you working?
hindi
thats what i speak primarily nowadays, but I've been taught the concept in english
I'm fine with english, but I can't for the life of me ever determine which graph is steeper
its a recurring issue
"steeper" means "more vertical-like"
ahhh, alright. so that would be the leftward one right?
lemme be simple'
ye
Speak hindi, if you like
You shouldn't have to compel him to
and when u imagin that]
If it helps to understand
Then you speak Hindi to him if you have an explanation that works
[good edit though]
haha, all good
This is a good diagrammatic example (though the slopes having numbers is a little misleading, since there's not much information here to determine its value in the first place)
But the visual aid should be enough to get the idea
it is, thanks!
helps when the line is straight,its a bit annoying when its curves like decay curves and what not, but I think I got the crux of it now
thanks again
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is it wrong to divide both sides by 5 here?
no it's never wrong to do that
But my answer is different from my lesson
It's not illegal
Just impractical
They factored x out of it instead of dividing by 5
You'd still have to factor x out here anyways
Actually complete the question here and you'll end up with the same answers
oh you're right
even with my x=-6/5 result?
how did you conclude that
Well i completed the square i think
half of b squared added to both sides?
and then that's just a perfect square of 6/5 because 36/25
But from what
i calculated it in my head, i don't know how i got this
But I mean what line here are you completing the square of?
If you were to complete the square here (though again you could just factorise the x out)
Then sure, you'd have 6/5 inside the brackets
What must you then subtract from the square to complete it?
no then we square 6/5 which is 36/25 and add that to both sides and
i think i forgot to add it to both sides
ye
ye
You should do
Bearing in mind that "square-rooting both sides" is a "needs a plus-minus" operation
Why? the RHS is in parentheses
in general, if $x^2 = y^2$, then $x = \pm y$
Pseudo (Cat theory #1 Fan)
one way to see this is $x^2 = y^2 \iff x^2 - y^2 = 0 \iff (x + y)(x - y) = 0 \iff x + y = 0 \lor x - y = 0 \iff x = y \lor x = -y$
Pseudo (Cat theory #1 Fan)
is this considered y?
The parenthesis isn't the problem-point; square-rooting is
yeah so i guess in this case
you have $a = x + \frac 65$ and $b = \frac 65$, and $a^2 = b^2$
Okay ty
That's y^2
Pseudo (Cat theory #1 Fan)
right
That makes sense

is this good?
yep
ye, though you can then evaluate these
Ty!
omg it's the same result!
i was wondering because i felt that finding the solutions of a line in a circle could be common in geometry and if i don't have a good conception right now (which i didn't have the best) then i would definitely forget how to do this later on in math
so i wanted to solve it myself
i had trouble with this because i thought -24/5+9/5=-15/5 and not -9/5
But i multiplied the 3 by 3 instead of 5
i understand it now, thanks a lot! 🩷
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how are electron movements instantaneous (the exitations etc..)
since it's a process that... certainly don't seem like happening instantaneously.
and what is it that gives off the photons? the movement of an electron or the change of shell of an electron
i think youll get some better answers in the physics discord
should be in #old-network but yea idk if youll get the answer u want here
@void vessel Has your question been resolved?
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Can I get some help with this please? My answer doesn't match any of the solutions, should I use the quadratic formula?
This is my work
what happened here
when you have -8, it's like -1 times that thing
so -(a+b) is -1*a + -1*b
it's -x**2 + 4x -4
I can help let me solve it give me a second
first i divided both sides by 2, and then i took out a gcf of -
And then I took b/2^2 and added it to both sides
also can't you just substitue each value in?
can you use the bot thing i can't visualize this easily in my head
forget it
Into the quadratic formula?
Can you tell me your steps?
i could but i wanted to test first if i could try other methods because the quadratic formula is a bit tedious
Okay thanks
First, the given is this system of equations, I set the first equation which is y equal to a quadratic set to -4x+16 equals that because in the 2nd expression that's what y is equal to
Then I set the new expression equal to zero to have it in standard form by adding 4x to both sides and subtracting 16 from both sides
So first thing you did is solve the system then set them equal?
solving it is just finding the x and y values that satisfy both equations
to do that you could for example do what i did, i think
I've never seen anything like this
The answer should be (2,8)
interesting
i don't remember taking systems of linear-quadratics before but this is in algebra 1b in my school
can you tell me what i did wrong? i'm not sure
so this is just solving -2x**2 + 8x - 8 = 0?
lemme try to do it
2 sec
Okay
well once you get the x value, you can input it to find out the y value for each solution to x or something like that
Your mistake happens in the first step of completing the square you dropped the negative sign
The whole point is to figure out where on the graph the linear line and quadratic curve intersect
there is no negative in front of the brackets
that's ur mistake
I'm supposed to not?
Yes
i divided both sides by -1
uh
it shouldve been x^2 - 4x + 4 = 0
that's not what you did tho
yes
i also did other steps
whered you get that extra 8 on the rhs
Yea
where did you bring 8 after taking (-1) common?
Actually you are supposed to keep and use the negative sign but you are NOT allowed to drop it
i got this first but then i realized that b/2^2 is 4 and that if i transfer 4 from the original expression to the 0 side and add 4 to both sides i get this so i just deleted the zero and put 8
i see, i was wondering because in the actual graph the curve would have to point downwards because -a in standard form means it points down
this quadratic only has one solution doesnt it?
i'm solving it and I only found one solution
Yea
x = -2
in my multiple choice there's no -2 for the x though
maybe i did it wrong
Ah
since u have ur x value u can get ur y value and u should find 2,8
Exactly
if it's 2 then if we take any one of the original expressions and input 2 into x you can find that for example y=-4(2)+16 = 8
hmm..
what does (b/2)^2 = 4 have to do with your actions
Yeah
how can i get 2 though?
to be honest it made sens that the quadratic only has one solution otherwise the system wouldnt work
i'll show u$
But aren't i doing things algebraically?
Well i don't see a value that satisfies a times c equals a+c=b
That makes sense
are you trying to split the middle term
oh there
never mind
There's a formula in my class that you can use to 'complete the square'
there are two soln for original quadratic
geometrically
yeah that
Yeah
no only one otherwise the system doesnt work
graph it
but you have to consider common
it crosses the x axis only one time
you can also use the discriminant to count the number of solutions and what type
were talking in general
Ah
yes
and would that yield a value greater than 0?
or would it be 0
/genq
if the quadratic only has one solution the discriminant HAS to be 0
Right
in the vertex form of the quadratic
Does that mean it's neither complex nor real or are 0 and above 0 both real and only below 0 imaginary?
when the discriminant is 0, the root of the discriminant cancels out,
Yea because sqrt 0 is just 0
the vertex in the x axis of a quadratic is -b/2a
if u look at the quadratic formula
doesnt it look oddly similar
so the root of the discriminant has to be 0
discriminant above 0: 2 solutions
discriminant=0, one solution
and 0 is only one solution
and below 0 is 2 complex
discriminant strictly less than zero= 2 complex solutions
np
that's not how they did it XD
both ways are right
but their way is definitely better i dont know why i didnt think of it
i was just trying whatever works first
and whatever is simpler and more elegant intuitively
we couldve indeed literally just set both equations equal
that's what i did
but i didn't group them at the last part
instead i found the perfect square
which is also a good method
when you're completing the square don't try to simplify the expression in other ways just divide by the leading coefficient
like say u have 8 x squared + 5x - 8
but earlier someone said you can't divide when it's -?
divide everything by the leading coefficient which is 8
why not?
because a quadratic with a negative a coefficient points downwards
and?
idk
I see what ur talking about
my answer clearly was wrong xd
so you can't divide both sides by -?
we're solving an equation here
yes you can
say u have 2 ligns of an equation
the lines are equivalent but not equal
-2x**2 + 6x is not the same as x = whatever
we're solving an equation here
that's not the same thing?
we're not looking for two equalities here we just want a value for x
yea, like those two lines arent the same thing but they're equivalent
we're looking for an equivalence
Yea i get what you are talking about
to be honest if u grasp this concept you're good
i suppose that if you substitute this then it won't fit both equations
it's often the understanding part that's hard
obviously not
most of the time math problems usually have very easy answers
like 2
Yeah because I learned real life examples of this that are really intuitive to me already, such as when pennies and dollars have the same thing
most of the time although
ur 4 + or minus root 8 isnt in any of the solution and just by looking at it
it wouldnt solve either
because you need to be able to generalize for everything instead of just knowing the answer
Yes
i've had answers similar to the sqrt one in the image that are true
in my class
but yeah they're mostly answers taht are basic
Yeah
in my classes since we are not allowed calculators during exams our professors usually put equations that lead to integer answers
usually
they trick you sometimes but still
gotta keep an open mind
Yeah because some questions aren't tedious enough for a calculator
when I get a weird answer I always double check
and for systems of equations you can graph the result
in your head?
there are so many methods to check and backtrack
ngl that's a bit hard
i dont think you would be allowed a calculator in an exam with something like this
because in systems of equations, especially irl examples, the answer isn't always an integer and so it's hard to approximate it
i didn't use one for this one i think. but i did use one for this
because intuitively i don't know that 157x157 equals 24,649
yea scrap completing the square for massive equations
too much room for error
Yea
also your calculator can solve polynomial equations on its own
u just write out the coefficients and it can do it itself
I use that in physics exams to avoid the headache
i wrote this in self evaluation, it's like what you said
because there's no way I'm doing 789504 squared
do you have a physical calculator
Yeah but i'm still in basic algebra where i need to do it on my own first to understand why it works and how it works
app
alr
Can i send you a friend request on discord!
Sure
Yay
we can move to discussion, if q done
Thanks everyone for helping me with this question, it wasn't easy
😭(||yes||)
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Renato
basically since 70 = 2x5x7, then 5 does not divide this number 24a^25.... but 2 and 7 does
call this number 24a^25 -2a^19 -2a = X, then
2 | X, 7 | X, but 5 does not divide X
24a^25 -2a^19 -2a = 0 (mod 7)
3a^25 -2a^19 -2a = 0 (mod 7)
3a^25 + 5a^19 + 5a = 0 (mod 7)
a^25 + 25a^19 + 25a = 0 (mod 7)
a^25 + 4a^19 + 4a = 0 (mod 7)
so one possible solution is a = 0 (mod 7)
i think
yep that is true. I would use fermat's little theorem here
simplifies things perfectly actually
(also notice that you are assuming that 7 does not divide a here, it's important)
a is a integer value from 0 to 6
only case that this shit is gcd(a,7) ≠ 1 is when a = 0
You haven’t worked mod 5 yet
your point?

What is your confusion with this?
the confusion was that I didn't noticed that a is in-between 0 and 6
the multiples of 7 are not considered as they count as 0 under mod 7
wait a second I am getting confused
Okay, so do you agree that the only way to get divisibity by 7 is 7|a?
ok sure
after simplifying with fermat a^19 = a(a^6)^2 = a = 0 (mod 7)
a^25 = a(a^6)^4 = a = 0 (mod 7)
Yes. So the whole thing becomes 2a(5-1-1) = 2a(3) = 6a mod 7
Hence, we need 7 | a.
That's one of the conditions.
Now you can consider the condition for modulo 5. We need that 5 does not divide 2a(12a^25 - 2a^19 -2a).
how?
dont skip steps please
\[24a^{25} - 2a^{19} - 2a == 2a(5a^{24} - a^{18} - 1) == 2a(5\cd1 - 1 -1) \pmod7\]
Need an help in French !
Cooly
Please see #❓how-to-get-help
Using that 12 == 5 (mod 7)
surely
Hm?
6a = 0 (mod 7) => 7 | a?
we can find the ones that work and exclude those
Yeah, 6 is invertible in mod 7.
Yes.
gcd(6,7) = gcd(6,1) = gcd(0,1) = 1
I mean sure. 6 and 7 are coprume.
since gcd(6,7) = 1, multiplicative inverse of 6 (mod 7) exists
24a^25 -2a^19 -2a = 0 (mod 5)
What is it then?
36 = 35 + 1
6x6 = 7x5 + 1
inverse of 6(mod 5) is 6
24a^25 -2a^19 -2a = 0 (mod 5)
Okay sure
gcd(a,5) = ?
if a ≠ 0 then gcd(a,5) = 1
a^25 = a(a^4)^6 = a (mod 5)
a^19 = a^3 × (a^4)^4 = a^3 (mod 5)
24a^25 -2a^19 -2a = 0 (mod 5)
4a + 3a^3 + 3a = 0 (mod 5)
7a + 3a^3 = 0 (mod 5)
2a + 3a^3 = 0 (mod 5)
@hasty mist i might need some helping hand
a = 0, a = 1, a = 4, I just tried every number a from 0 to 4
X = 2a(2a^24 - a^18 - 1) (mod 5)
= 2a(2 x 1 - a^2 - 1) (mod 5)
= 2a(1 - a^2) (mod 5)
Isn't that right?
If you check for a = 1,2,3,4 here I think you get that a cannot be 1 or 4.
Yeah, so a == 2 or a == 3 mod 5
Now you can use CRT to combine those conditions.
\[
\t{System }1 = \begin{cases} a == 0 \pmod 7\\ a == 2 \pmod5\end{cases}
\]
\[
\t{System }2 = \begin{cases} a == 0 \pmod 7\\ a == 3 \pmod5\end{cases}
\]
Which is the same thing anyway..
what?
sorry
From the first condition, we have that a == 0 mod 7
Yes?
sure
And in order for 5 not to divide X, you need a == 2 or 3 mod 5
So you can combine those conditions with CRT.
can't we solve just one system
why we need 2
because its an OR not an AND
i guess so
I don't know why I said that. I'm under some influence of opioids due to being hospitalised. You need to solve both systems of equations.
\[
\t{System }1 = \begin{cases} a == 0 \pmod 7\\ a == 2 \pmod5\end{cases}
\]
\[
\t{System }2 = \begin{cases} a == 0 \pmod 7\\ a == 3 \pmod5\end{cases}
\]
Cooly
i see, though you are still functioning very well
i like dat
The two congruences are equibalent in isolation but yhey yield different solutions when combined with a == 0 mod 7
Mi yi = ci ( mod mi )
5 y1 = 0 (mod 7)
50 = 49 + 1
y1 = 0 (mod 7)
7 y2 = 2 (mod 5)
21 = 20 + 1
y2 = 6 (mod 5)
y2 = 1 (mod 5)
y1 = 0, y2 = 1
xi = Mi yi
x1 = 5 × 0 = 0
x2 = 7 x 1 = 7
a = 0 + 7 = 7 (mod 35)
the solution to the first system is just a = 2 (mod 5)?
is 2\equiv 0 mod 7?
no
so is this a correct solution to the first system?
if the solution is a\equiv 2 mod 5 then a=2 should be a solution since 2\equiv 2 mod 5 right?
and if 2 is a solution to the first system then 2\equiv 0 mod 7 but thats not the case
for systems like this with small moduli (and a small number of equations in the system) the fastest way is to probably manually find a solution
so first you want a number a that satisfies a\equiv 0 mod 7
whats the smallest natural number that satisfies this?
by RRT you mean chinese remainder theorem ig, you can do that np but its faster for you to manually find the solutions
like in the exam you need this extra time that you can save
is just this
nice
i was taking modulo 5 instead of mod 5x7
Mi yi = ci (mod mi)
M1 = 5, M2 = 7
5 y1 = 0 (mod 7)
15 = 14 + 1
y1 = 0 (mod 7)
7 y2 = 3 (mod 5)
21 = 20 + 1
y2 = 9 (mod 5)
y2 = 4 (mod 5)
xi = Mi yi
x1 = 5 × 0 = 0
x2 = 7 × 4 = 28
a = 0 + 28 = 28 (mod 35)
that should do the trick @smoky egret @hasty mist
nice job
Well done.
hope your recovery goes well
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I’m a little confused, if f(0)=0 how does that immediately imply C=0?
ln|0+1|=?
so fucken cool
also where are the dx's
interesting
yeah but it’s not working for the problem I’m on rn
no it has too many symbols per page to be targeted to tiktokers
can’t really do a=0 😔
nah this shit is ass
how did pi happen
typesetting lowkey hurts my eyes
this looks like a completely different function
correct me if I am wrong
It’s a different question
I’m just confused cos like
so you put some other value of alpha that works
can I make a= anything?
0 isn't sacred
well yeah
but then I also get f(1)=C which doesn’t really help I think
the answer is 0 but I don’t see how I can get that
honestly maybe feynman technique ain't very good here
how about x=e^u on the original integral
Hmmm I’ll try that
Slight NB about the notation here:
Once you've integrated that dx, the function is in alpha only
So the derivative outside the integral, i.e. of f(alpha), is a full derivative (not partial)
Also, you mentioned alpha := 0 doesn't lead you anywhere
Sure, not at the end, because of the log
mmm yeah I see that vision
But what about where you defined f in the first place?
f still has lnx on the top so 0 still doesn’t work I think
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ok so my maths teacher and i quote believes its non sense
and he told me to rewatch the youtube video
1 second ill show u what way he does it
and he's asking me why the numerator and denominator are the roots or whatever
and he thinks
its a conwindence it works
and he asked me why it works
its not
ikr
wait which way did you do it
is your teacher... chatgpt? we usually advise against using AI here, as it can lead to misinformation
this one or prev
+this is the way i self thought from yt
that's how i learnt it lol
no no, i just used chatgpt cause idk latex
in school
and its easier for your guys
this is exactly how i learned it im p sure
it's very easy to prove why it works
imma dip, best of luck to you two 
he wants me to rewatch and prove it, do you know how ill prove it
Yes it's trivial
should i just say its a amsyptopde and hope he understand what that means
he uses this way
since idk squaring both sides so the inequalitie doesnt flip
but is he asking you why your method works
if the x is a minus
yes
its proof by cases
and he told me infront of the class that its non sense
Hes dumb
yeah i told him, but he just explaion to me how it works
but ill be honest idk how it works
but it just does
you should get an understanding of why then
and i dont wanna ask ai, cause like the guy said earlier, it just might lead to mis information
can you give me 5 mins i gtg
no yeah thatts why i came here to ask why
I'll write the proof after
yeah np
ok tyyysmmm
Your method is equivalent to your teacher's method; note that after your Step 3, if instead of doing it by cases, you multiply both sides by (x+2)^2, then you just go to your teacher's Step 4.
yeah thats one way of looking at it
but i just want to prove that
can just as easily get you
the answer
without going the long way
I don't think either of you is going "the long way". Doing by cases is not that easy to formalize, it might use some notions that you may have not seen (continuity, intermediate value theorem), which the parabola way avoids by using a convexity argument (have you seen what it means for a function to be convex?).
i lost you
no i havent seen that lol
but ill look into it
but ill put thatt point forward, to my maths teacher, considering he probably knows what that means and it might broaden his understanding of what im trying to do
Yeah, no need, your teacher won't expect you to know that. The thing is, he should know that doing by cases is a formal way of doing it, so I don't think there really is a point of arguing with him; just learn his method, and he'll stop complaining.
cause instead of sayin critical points, i said special numbers, cause i didnt know the word for it at the time
yeah thats fair enough, he asked me to rewatch the video and come back to him, he said it was 'interesting'
so 🤷♂️
im happy i have a teacher thats opened minded at least yk
Yeah technically its because of halfspaces buuut I mean its just checking if each term is pos and neg and when that happens
You can argue by showing each case is handled correctly
yeah i need to look into that, im watching some more youtube video, and the first video never mentioned about the pos and neg thing, just told me to take a random number in between the 2 and see if it works
if it works its true
if not its false
it works because they all have the same sign for each term
so checking any one of them checks everything in that interval
But if you want a rough explanation, the intuition is that on either side of $x=-2$, the function $f(x) = \frac{-x-9}{x+2}$ is continuous, basically meaning that you can draw its graph without lifting your pen from the paper. This means that if $f(x)$ were to change sign on either on the intervals $(-\infty,-2)$, $(-2,\infty)$, it would have to cross the $x$-axis (it would have to equal 0). Since the only spot where $f(x)=0$ is at $x=-9$, then it doesn't change sign on teh intervals $(-\infty,-9)$,$(-9,-2)$, and $(-2,\infty)$.
Feltheshovel
yes continuity ftw
ok ty 🙂
ty so much guys for ur help
i appriciate it so so much
Also, don't always look at things negatively; he may have feigned to doubt you so you would try to understand why your own method works. Even if that was not his intention, you must admit that you learned more from this than if he had simply told you that you were correct.
that exactly how im looking at it lol, ill be honest, i didnt have a clue how it worked
and it was nice learning about it
now i like properly understand it
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need latex help
how do I make my background white?
shi
Sniped
Yes
Yeah
Move theee
yes to which
The first
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,tc color white or somehting like that
Unknown colourscheme white or somehting like that. Valid colourschemes:
white: Pure white background, with black text.
light: Very light grey bckground, with black text.
grey: Discord-grey background, with white text. (Recommended)
darkgrey: Dark grey background, with white text.
dark: Dark background, with white text.
black: Pure black background, with white text.
transparent: Transparent background, with white text. (May cause issues)
trans_black: Transparent background, with black text. (May cause issues)
oops.
The latex people hangout around there
🥀
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Renato
1 + 1 + a + 2 + a + 1 - 1 ≠ 0
2a + 4 ≠ 0
a ≠ -2
w^3 = e^{2ki.pi/3} , k ∈ {0,1,2}
Isn't this w, not w^3?
Yes lol you wrote w^3 for the right side equation in your previous message
wait yes
wait
so you saying w^3 = e^{2kpi × i}
Well, notice that no matter what w (unless it is 1) is, {w, w^2, w^3} is the 3 roots of unity
w not w^3
so w^3 is?
)