#help-49
1 messages · Page 112 of 1
A dense set(Ping when reply)
Is what I've done so far
now to procced I suspect I'll need MVT
not sure how to apply it though
g' is the limit of that expression as h tends to 0 (if it exists)
You should get that the integral is h•f(a_n) for some a_n in (x,x+h)
that's assuming you know the derivative
which you don't
you must use the continuity of f to conclude
your notation is very poor for this purpose
As f is continuous, the integral is between min(f) (h) and max(f) h
but that doesn't really help much
$min(f)h \leq \int_{x}^{x+h} f(t) dt \leq max(f)h \implies min(f) \leq\frac{ \int_{x}^{x+h} f(t) dt}{h} \leq max(f)$
also I wouldn't write f(x)dx
when x is the point where you're trying to differentiate on
okay, so ftdt
A dense set(Ping when reply)
min and max of f taken on which domain?
I'll now have to prove that $min(f(x),f(x+h)) =f(x) = max(f(x), f(x+h))$
A dense set(Ping when reply)
as h tends to zero
uh no
wut
first of all
how did you reduce min(f) to min(f at two points)?
and even so, why should the min be equal to f(x)?
right
(same questions for max)
well, it's the min and max on the interval [x,x+h]
ok
do we agree that for any h > 0, it won't be equal to f(x)
so what do we expect to use now?
(maybe it might)
generally xd
I feel I need to squeeze it somehow
squeezing this way will not be fun
you are missing some steps that make your life much easier
well you need to prove min(f) on [x,x+h] converges to f(x) when h-> 0
same for max
but you could have done it alternatively
for example finding |(g(x+h)-g(x))/h - f(x)|
well, for that i have to prove $\lim_{h \to 0} f(x+h) = f(x)$ no?
A dense set(Ping when reply)
again, is f(x+h) the only point that matters in [x,x+h]?
A dense set(Ping when reply)
yes
so $f(x+a) = f(x) \forall a \in [0,h]$ is what what i need
A dense set(Ping when reply)
no
that would require f to be constant on an interval to the right of x
not all continuous functions are like that
i think constant functions are like that 
maybe (g(x+h) - g(x))/h - f(x) might be clearer...
continuity is gonna sneak into this somehow
yup
hmm
Using the bounds you gave and the continouity of f you're showing the lemma I suggested to use.
I don't understand this
you already computed that $\frac{g(x+h)-g(x)}{h} = \frac 1h\int_x^{x+h}f(t)dt$
rafilou is not not born in 2003
yes
subtract f(x) to that
$g(x+h) - g(x) = \int_{a}^{x+h} f(x) dx - \int_{a}^{x} f(x)dx$
\
$\frac{g(x+h) - g(x)}{h} = \frac{\int_{a}^{x+h} f(x) dx - \int_{a}^{x} f(x)dx}{h}$
\
$g'(x) =\frac{ \int_{x}^{x+h} f(x) dx}{h}$
\
$g'(x)-f(x) = \frac{1}{h} \int_{x}^{x+h} f(t) dt - f(x)$
A dense set(Ping when reply)
"g'(x)" is again dubious
there's some h in there that is unwarranted
and we don't even know if g'(x) exists since we haven't proved differentiability yet
the statement says differentiable on (a,b)
Also g' is the limit of that ratio as h tends to 0
g might not be
you must prove it is
that's literally what YOU have to prove
using something that remains to be proven in its own proof is... circular
okay so we'll have to prove the min and max go to f(x) seems good 👍
i didn't give the bounds tho
okay, so
$\frac{g(x+h) - g(x)}{h} - f(x). = \frac{1}{h} \int_{x}^{x+h} f(t) dt - f(x)$
oops

_
Yeah, just wanted to mention that I didn't intend to use differentiability to show differentiability
A dense set(Ping when reply)
on the same page now 
ok, any way to put the f(x)... inside the integral?
hmm
(just do it)
instead subtract $\int_{0}^{x} f(t)dt$ from both sides?
A dense set(Ping when reply)
hint: $\ds f(x) = \f1h\int_x^{x + h} f(x) \dd t$
just evaluate it and see
how does a constant get integrated
is \f an existing latex abbreviation or is it a personal-made command? I still don't know how to do those
it's mine
hmm, okay
ykw, I'm kind of lost, I think I'll do some examples first, and then prove it?
not sure if examples will show you the proof
this proof is probably one of those you get more used to as you do a bunch of different proof examples in real analysis
doing calculations won't really elucidate it
because the idea itself is quite abstract
where proofs are dispensed with
blackboxed for future study
It felt very handwavey so I asked here
there's definitely some detail to be filled
this is the meat
one proves this much more carefully in a real analysis class
So for now I just go with this, right
sure why not
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is the integral over (a, b) and [a, b] the same? if so why?
@rapid tapir Has your question been resolved?
I dont think so, i believe the first interval might be a variation of ⟨a,b⟩, where it includes all the numbers between a and b, without including a, b
While the other one [a,b] includes both a and b
Oh, you were talking about integrals, not intervals, srry
But regarding integrals, i would say it depends on the function, and the values of a,b
eg if the indefinite integral is 1/x
the ranges (0, b), and [0,b] could be different
But for like fully continuous functions, i would say their similarity doesnt matter since the result doesnt change alot
if f is defined over [a,b], then if f is integrable on one of them, f is integrable on the other and the integral is the same
the point is that the "mean" over an interval, an uncountably infinite amount of points, won't change due to counting the value of 2 more points
why not? wouldn't (a, b) means that you are excluding a, b from the area?
{a} and {b} on their own contribute 0 area
does removing two thin lines (of thickness = 0) change the area?
no but is it really 0
yes
isn't it like infinitely small?
the thickness is exactly 0 isn't it
so the area is exactly 0
another way to view it: if you view the integral as the limit of the riemann sum
then no matter if you account for f(a) and f(b)
since the coefficient in front is similar to 1/n
so I could very much add or remove those two
when n goes to infinity, the impact adding/removing f(a) or f(b) goes to 0
so taking the limit, there is NO difference at all
which coefficient
@rapid tapir Has your question been resolved?
have you seen riemann sums?
,ask 0.99...
(b-a)/n * sum(f(a+k(b-a)))
I think same logic is used here
I don't think it's directly related to 0.(repeating9), they just share "sum that increases number of terms at each iteration"
it's the (b-a)/n that makes everything
sure, your f(a) might make a difference at the first iterations, when n = 1, n=2 or other small values
but when n gets big
like infinitely big
no one is gonna notice if you get rid of a single term in the sum
in the 0.(repeating 9) = 0.9 + 0.09 + 0.009 + ...
if I get rid of a single term in this sum
for example 0.009
the result is immediately changed
we would obtain in this example 0.991
The difference between 0.9... and 1 is basically zero due to the infinite repeating nature of 0.9..., now if you have two intervals r=(a,b), p=[a,b]. You can think of p_1 as (r_1-1).999, so a = (r_1 - 1).99999..., a = r_1 - 1 + 0.99..., a = r_1 technically
So the first element of the interval r is basically very near to the first element of p, to the point where the difference between the two is zero
Now when you have a fully continuous function thats integrable on both the intervals r and p, the idea that a = r_1 basically suggests that integration over any of the two intervals is basically equal
,ask r_1 - 1 + 0.99...
@rapid tapir Has your question been resolved?
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$\frac{dx}{dt} = -\frac{k}{2\pi} [\frac{1}{x(x-1)}]$
Mortta
erm how to solve for t?
Separation of variables
yes
@stable halo Has your question been resolved?
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I know that ln(e^x) = x, but it didn't like that either 🤔
When you have h = int from a to b of f(x) dx then h' is just f(b) - f(a)
??
That woulb be a number
it wants the first part not the second
Oh
Soz i read it diagonnaly
smeagol
Yes
he says do u substitution
u = e^x , du/dx = e^x
,, u = e^x , \frac{du}{dx} = e^x , \frac{dh}{dx} = \frac {dh}{du} \frac {du}{dx}
smeagol
,, h'(x) = \frac{d}{du} \int_{1}^{u} 3ln(t) dt \cdot \frac{du}{dx}
smeagol
,, = 3ln(u) \frac{du}{dx}
smeagol
,, = 3ln(e^x) \cdot e^x
smeagol
why is du/dx added on the end
ohh I think I see
,, \frac{d}{dx} = \frac{d}{du} \cdot \frac{du}{dx}
smeagol
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Multiply by the conjugate
And you'll see that the math for that problem will do that
Hint : indentity
It's not always going to be 1 in the numerator
It was just a coincidence for that problem to have the math work out to be 1
so you have 1 / a + b
then you multiply by conjugate
so you have (a-b) / (a+b) (a-b)
but how do you simplify it
sorry i am confused
Result:
0.99999994039536
it's nearly 1
Yes, exactly
Result:
1
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how do i go about factoring x^3 +3x^2 -54 = 0?
x=3 is a root -
then just divide it by x-3
or perhaps you could use cardano's formula https://en.wikipedia.org/wiki/Cubic_equation
If you turn it into a depressed cubic equation then yes
can't you do it all the times ?
𝔸dωn𝓲²s
right
@carmine tide Has your question been resolved?
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hello can someone help me with this
@tepid parcel Has your question been resolved?
<@&286206848099549185>
You didn’t square the denominator
for to=he quotient rule i feel like the numerator is too complicated as well is there something wrong with my calculations?
sorry just forget about the red writng i was just testing like different workings
Actually your calculations look fine the first one
When you tested f”(5) you said 6-5=-1
Your original f”(x) was right
The red writing?
This one
The black
I was looking at the red which is why I was confused
It should be
$-6\sqrt{6-x} - (-\frac{12-3x}{\sqrt{6-x}})$
parm
It’s not -12 it’s $-(\frac{12-3x}{\sqrt{6-x}})$
parm
oohh okok
man my head is about to burst i havent slept, sorry if i kept on making mistakes, ill close now, THANKS
.close
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@grim monolith Has your question been resolved?
i dont think you should be finding their mass
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How do I solve this?
@vagrant mica you can close this
.close
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when you graph a derivative and when its positive is it possible for the second derivative to be negative?
oh yeah
thx
but i get it now idk what i was doing
.close
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need help and on some other questions
y + 4 > 2x
y > 2x - 4
the line should be y = 2x-\4
and the area is above that line
is y > 2x - 4
a b c or d?
a
yo
?
Hmm.
can u help me wtih the above image
Bro I'm in the unit right below yours 😭
I would help/
Systems of Equations
Is where I'm at.
ohhh
Your in HS I presume?
Me to.
can anybody help me with this
@outer beacon Has your question been resolved?
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Little bit of problems on these
I had to skip the lesson today for math because i was sick
So i dont exactly understand some of these topics
for the simulation question i got 562.34 for the initial value and 1.78 for the common difference
the other 2 i just5 tried using desmos to try and approximate an answer
(calculator active)
@sharp prairie Has your question been resolved?
,w (-2,11), (0,6), (4,2), (8,1) exponential model
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.reopen
✅
,calc 6.19205 * exp(-0.283359 * 4) - 2
Result:
-0.0066229486083098
I don't get the question
if you are supposed to find a model that passes through exactly 2 points
which 2 points are you even supposed to choose
also your question 3 is obviously wrong
the population is 50,000 or less is literally in the question
start by finding the equation
it's y = 1000 * a^(x - 2) for some real number a
(what happens when you sub in x = 2 into this?)
use x = 6, y = 10000 to find a
then sub in x = 4 to find the population on day 4
,w exponential model (2,5.63), (3,8.44), (4,12.66), (5,18.98)
,calc 2.50384*e^4.05118
Result:
143.8837315194
yeah your question 6 answer should be correct though
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where this came from?
ig its unrelated to the question
wdym?
that second part isn't related to the question i think.. you already got the answer right.. that x = 0 y 0 and z = 0 are the only solution to the equation
so for homogenous determinent x,y,z is always 0?
delta here is 40 so how come x,y,z is 0?
do you know Cramers rule? smth like that
yeah
read it again probably that will help... it mentions the conditions for homogenous equations as well
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$\frac{d^2}{dx^2} \int_{0}^{x} (\int_{1}^{sin(t)} \sqrt{1+u^4} du) dt$
\
differentiating once , we get
\
$\int_{1}^{sin(x)} \sqrt{1+u^4} du)$
\
Differentiating again we get
\
$cos(x) \sqrt{1+sin^4(x)}$
A dense set(Ping when reply)
Does this seem right?
wdym
i'm not sure if you're also looking at the same picture as i am
because i'm seeing some pretty 
the mathematics is fine though
probably
hmm, okay
Calculate [ \dnv 2 x \int_0^x \parens [\bigg] {\int_1^{\sin(t)} \s {1 + u^4} \dd u} \dd t. ]
Differentiating once, we get [ \int_1^{\sin(x)} \s {1 + u^4} \dd u. ]
Differentiating again, we get [ \cos(x) \s {1 + \sin^4(x)}. ]
compare the quality of the typesetting ^
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Calculate
$$\frac{d^2}{dx^2} \int_{0}^{x} \left(\int_{1}^{\sin(t)} \sqrt{1+u^4} du\right) dt$$
Differentiating once, we get
$$\int_{0}^{1}{\sin(x)} \sqrt{1+u^4} du)$$
Differentiating again, we obtain
$$\cos(x) \sqrt{1+\sin^4(x)}$$

higher!
wdym
using $$ in latex is a crime
the correct thing to say is "i never use $$"
:kekhands:
Calculate
\begin{align*}
\frac{d^2}{dx^2} \int_{0}^{x} \left(\int_{1}^{\sin(t)} \sqrt{1+u^4} du\right) dt
Differentiating once, we get
$$\int_{0}^{1}{\sin(x)} \sqrt{1+u^4} du)$$
Differentiating again, we obtain
$$\cos(x) \sqrt{1+\sin^4(x)}$$
higher!
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
use \[ \]
higher!
higher!
Calculate [\frac{d^2}{dx^2} \int_{0}^{x} \left(\int_{1}^{\sin(t)} \sqrt{1+u^4} du\right) dt]
higher!


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since no other context is given
A, B, C, and D can be anywhere right?
as long as they’re along the circumference of the circle?
the question was to determine whether the area of the quadrilateral ABCD > 40 or not but well we can’t really tell?
A, B, C and D can be anywhere, yes
given arbitrary A, B, C, and D on a circle of radius 5, can you determine whether the area of ABCD will always be bigger than 40?
if no, give a counterexample. if yes, then prove it
cant we like.. make A,B,C,D arbitrarily close
!xy
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
ABCD can’t overlap
it’d not be a quadrilateral then
it’s be a degenerate one
that is the actual question? i just wanted clarification
how about they are really really close
yeah okay so it can be close to the area of a circle
or close to zero area
40 is not the circle area so it’s not the upper bound for the area of a circle
so the assertion is false
right?
yes
okay then
thanks
.close
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Can I have a hint as to how I'd go about this
I'd start by consider the set of integral lower and upper bounds
then what
I'm wondering if WOP can help us in anyway here
wop ?
well ordering principle
m is not unique
conside x = 1
then 0 <= x <= 1 and 1 <= x <= 2
one of those inequalities would need to be sharp
oops
We now prove if $x \in \R$ there is a unique integer $m$, such that $m \leq x < m+1$
A dense set(Ping when reply)
yes WOP works here
We first assume $x>0; x \notin \Z$
in that case the set of all integral upper bounds are subsets of the naturals, and thus have a least element, let this element be $m$
so $x<m$.
A dense set(Ping when reply)
We now prove there exists $m$ such that $m-1<x<m$
A dense set(Ping when reply)
This is equivalent to proving there exists $m$ , such that $\frac{m-1}{m} <x/m<1$
A dense set(Ping when reply)
ykw, I'm lost
Hmm, and by WOP, this set has a least element
LooseEthics
Then by the wop there exists $a_{min}$
LooseEthics
yup
Let m = a_min
so $x<m$
A dense set(Ping when reply)
we now assume $m-1>x$
A dense set(Ping when reply)
and try to arrive at a contradiction
m is the least element of S, done
A dense set(Ping when reply)
let to the contrary $m-1>x \implies m>x+1$
A dense set(Ping when reply)
you don't need to, that side allow equality
I'm assuming $x \notin \Z$
A dense set(Ping when reply)
why?
I feel it makes the problem simpler
x<m and m is the smallest such integer. so x<m-1 cannot hold, so x>=m-1 has to
and thats it
Why can't $x<m-1$ hold
A dense set(Ping when reply)
ah yes
and clearly m-1 < m
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This is the question
Some values are given
And i need to solve for x
I have no idea how to get it
Mayb give some hints on how to solve?
The things in tube are 2 different liquids with different densitys*
,rotate
idk how to do the problem; just helping others answer
me neither
i have no idea how sin37 could be helpful in any way
nor the density of said 2 liquids
but looks like some kind of tricky mamometer problem
it is*
@carmine latch Has your question been resolved?
no
circle liquid
both of them mention the density of liquids
in the tube
i js want
hints
on what to do
not the answer itself
@carmine latch Has your question been resolved?
@carmine latch Has your question been resolved?
??????
u can ping the helpers
idk much
but i think you have to equate the pressures on both sides
and w the help of the angles, u can find the height of the liquid
Yes
The pressure of yellow and blue parts will be equal
Also sin is useful because we only look at the vertical height of the liquids
Not diagnol
My answer comes out to be 10cm. I'm not sure if it's correct though.
@carmine latch Has your question been resolved?
equalize pressures
they are at different levels
you cant say that those pressures are equal
Ooo
I was thinking like 1 • g • 9 ⅘ = 1 • g • x ⅗ + 8/10 • g • (13-x)⅗
Is this wrong?
Guess I'll ping you @long dagger
lol
I am
Understanding
Nothing
Meh ill leave it to a proffessor or something
Sorry for taking so much time to answer
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Well, I still can't find average of all distances from a point to a polygon 3+D using Green's Theorem, square root makes it too complex and finding distance squared is not an accurate thing, what can I do? This is for draw order of a 3+D drawing engine, anything else that would work? Polygons are planar, closed, not self intersecting, and all straight lines. To mitigate inaccuracy, staying within minimum and maximum distances of all vertices and centroid might be good. What else? X E.
In case it helps, I can consider polygons like 2d. X E.
I plan cutters so all shapes will be not intersecting except edges and not intersecting except edges on 2d view plane, and not intersecting planes of each other. I don't have that yet. X E.
I have really efficient and accurate to computer precision cutters and point in polygon algorithms. X E.
Maybe I should try min distance and max distance and keep it within those? How do I do that?
Some things to know, average of all distances should be greater than or equal to distance to centroid, average of vertices distances should be greater than or equal to average of all distances. I think I am correct, am I? X E.
With that I can generally mitigate inaccuracy but is this last one correct?
Should I close and make that last one my question?
.close
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Given the polynomial ( P(x) = x^2 - 4x + 6 ). Define the polynomial ( Q ) by
[
Q(x) = P(P(x)) - x.
]
The sum of all real roots of ( Q ) is . . .
[
\text{a. } 4 \quad \text{b. } 5 \quad \text{c. } 6 \quad \text{d. } 7 \quad \text{e. } 8
]
m13
Expanding gives x^4 - 8x^3 + 24x^2 - 33x + 18
Factoring gives (x - 2)(x - 3)(x^2 - 3x + 3)
Observe that, x^2 - 3x + 3 has a discriminant of -3, which means it has no real roots. Therefore, the only real roots are 2 and 3 and the sum is 5.
Is there another approach to solving this problem, other than just expanding and factoring
For a polynomial $x^n+ax^{n-1}+bx^{n-2}+...$, the sum of the roots is $-a$
SWR
Well
Gotta be careful with that
The problem asks for real roots, thats why i don't use Veita
Q(x) = (x - 2)(x - 3)(x^2 - 3x + 3),
(x^2 - 3x + 3) does not have real roots. By using, Vieta, it's going to be a mistake.
@neat silo Has your question been resolved?
@neat silo yeah I see no better way. The real roots caveat really screws you
I couldn't dig up any research that relates to that.
There are ways to tell how many real roots a polynomial will have, but you can't get their sum
How so
I'll just compute the sum them
Knowing how many real roots is crucial
How can you compute the sum if you only know how many real roots there are?
In mathematics, the Sturm sequence of a univariate polynomial p is a sequence of polynomials associated with p and its derivative by a variant of Euclid's algorithm for polynomials. Sturm's theorem expresses the number of distinct real roots of p located in an interval in terms of the number of changes of signs of the values of the Sturm sequenc...
It's definitely not an easier way though
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i need help with question 6, genuinely don’t know how to start nor continue. the answers r in blue but idk how to get them
if f(x) = x^2 then with f(x-b) you want to replace x with x-b wherever it comes up so f(x-b) = (x-b)^2
once you do that the general equation should look more familiar
but where do i go from there ? i just genuinely have no clue how to do this
well what you have is a general equation for completing the square, so at x= b you have the minimum and y=c is the minimum if i remember correctly
am i supposed to multiply (x-b)^2 out
well if you use the table you can find b and c. Once you've done that you can take another value from the table and use that to find a so say i took x=1 the table says y= 39 so a(1-b)^2+c = 39. You know what b and c are so you can put those numbers in and when you do you get an equation to get a
look for which row y is the lowest number
at (-3,7) ?
yeah
so you have b = -3 and c = 7
its like for (x-5)^2+10 the minimum point will be at (5,10)
so i can choose any point to find what a is as long as b = -3 and c = 7
yep
besides (-3,7)
np
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@timber arrow Has your question been resolved?
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Is there an intuitive explanation (without using calculus) for why the area under the sine curve from 0 to π/2 is exactly one?
@quaint field Has your question been resolved?
@quaint field Has your question been resolved?
Probably not :(
there's that animation on youtube
Mfw Matt Parker didn't finish his part on time :((( Nvm that, enjoy this shtfest! =D We are going to integrate the cos(x) from 0 to pi/2 in basically 24 different ways! Starring:
-Dr. Peyam: https://www.youtube.com/channel/UCoOjTxz-u5zU0W38zMkQIFw
-3B1B: https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw
-Think Twice: https://www.youtube....
skip to mathologer's proof
@quaint field Has your question been resolved?
this is awesome
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Kenzo
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Kenzo
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do \sqrt{}
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and for fractions do \frac{}{}
{} not ()
it’s next to the p
where the brackets are
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$\frac{a}{b}$
knief
are you finding y’
Kenzo
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nice the parentheses next to dy/dx are unnecessary though
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mhm
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so $y = \pm \sqrt{16-4x^2} = \pm 2\sqrt{4-x^2}$
knief
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Kenzo
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yep
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how’d you get this
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if it’s explicit you won’t have two dy/dx terms nor will the coefficients of dy/dx be anything other than 1
it’ll just be dy/dx = …
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right so how did this happen
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how is y a coefficient or how is there a 2 and all of that
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right but when you differentiate the side with just y the derivative will be dy/dx
that’s it
nothing else
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the derivative y isnt y dy/dx
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i think you’re missing the point
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suppose we have an explicit function y = g(x) then we will always get dy/dx = g’(x) where g’(x) and g(x) are simply functions of x and x alone
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huh
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i’m not sure what you didn’t understand
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^^^^
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ok then correct that
Kenzo
yea sure
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yep
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see this is strange though because we will get two different derivatives since the relation given doesn’t represent a function
are you sure they asked for explicit
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,rotate
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🤔🤔
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ok
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looks good just simplify a little
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uhh
Kenzo
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sure but i don’t like how there’s a pm tbh usually depending on the context we choose which branch we are dealing with
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can i see the graph
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yea i mean maybe he wants the pm but tbh id split it to be more clear
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like write it with the + and indicate which branch it’s for and the same for the - branch
yea
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the the +sqrt branch vs the -sqrt branch
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brother
i’m not referring to y’
i’m referring to y
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i know y’ is positive for the - branch
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ok
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factor out sqrt(4)
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Kenzo
yes then slope intercept form
and for y’
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f(x)-f(a) = f’(a)(x-a)
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you use both
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he said find the two tangent lines
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hmm
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do you ever do these yourself first
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because you resort to looking at solutions or getting help without thinking about it
hence why you don’t learn
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then think about it for a while
or look at notes
but don’t look at notes for awhile
problem solving doesn’t consist of immediately just writing the solution every time
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hence why you don’t get much better
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alright
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Closed by @upbeat plinth
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prove that a set with n positive integers always have atleast one subset that the sum is divisible by n
taking mod n seems good here but im not sure how i can continue it
is there some additional constraint on the n integers?
Coz you can always find n primes
Ohh, okay. I see
@viral dagger Has your question been resolved?
mod n can only have n-1 remainders if not divisible and there must be two subsets with the same remainder
makes sense
@viral dagger Has your question been resolved?
@viral dagger Has your question been resolved?
Is just the subset {n} allowed
n isnt always in the set
So not consecutive integers, just random
yes
@viral dagger Has your question been resolved?
order the elements x1,...,xn
and let Sk be the sum from x1 to x_k
there are n such sums in total
if one of them is 0 mod n, you win
if none are 0 mod n, pigeonhole principle...
php would be this, but i dont understand what that can do
or rather, there must be atleast 2 with the same remainder
say you have 1, 2, 3, 4, 5, 5, 6 mod 7, then the partial sums are 1, 3, 6, 10, 15, 20, 26 -> 1, 3, 6, 3, 1, 6, 5 mod 7. None are 0 here, but you are guaranteed that two partial sums are equal to each other, in this case 6 = 20 mod 7 for example, so 1+2+3 = 1+2+3+4+5+5 mod 7, then just take the difference between these two, which is 4+5+5 = 0 mod 7


