#help-27
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Hi I have the set ${ ax+b | a,b \in R \ \text{with} \ a \neq 0 }$ that defines all polynomials with degree 1 and the relation ~ where $ax + b \sim cx + d$ if $\frac{a}{c} > 0$. I need to check whether its reflexive, symmetric, antisymmetric and transitive. Is my solution correct? \
(1) Its reflexive because given $ax + b$, since $\frac{a}{a} = 1 > 0$, $ax + b \sim ax + b$. \
(2) Its symmetric because if we have two polynomials $ax + b$ and $cx + d$, if $ax + b \sim cx + d$, there are two cases for $a$ and $c$, the first one being $a, c > 0 => \frac{c}{a} > 0$ and the second one being $a, c < 0 => \frac{c}{a} > 0$ which implies $cx + d \sim ax + b$ \
(3) Not antisymmetric because for example $5x + 8 \sim 6x + 4$ (as $\frac{5}{6} > 0$) and $6x + 4 \sim 5x + 8$ (as $\frac{6}{5} > 0$) even though $5x + 8 \neq 6x + 4$ which means it cant be asymmetric \
(4) It is transitive because if $ax + b \sim cx + d$ and $cx + d \sim ex + f$ then $a$ and $e$ always have the same sign meaning $\frac{a}{c} > 0$
use $\sim$ for ~
aPlatypus
thx
also if you want a line jump in the latex you need to add two new lines
p1za
sorry
eh its fine we're not born latexers
not sure what you're doing in 2), how does that show symmetry ?
and a small typo in 4), you mean a/e right
@stone silo
yes
well we need to show that $\frac{c}{a} > 0$ given that $\frac{a}{c} > 0$. For the latter to be true, $a$ and $c$ need to have the same sign (and they cant be 0 anyways). If they both have the same sign then $\frac{c}{a} > 0$ is also true
p1za
and since $\frac{c}{a} > 0$ is true, $cx + d \sim ax + b$
p1za
@stone silo Has your question been resolved?
so is everything fine? @sullen island
yes
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Hi.
So I need some helps on an ODE. The question is $(x-y)dy=dx$ and I can't seems to find a correct answer.
alstom.metropolis
Here's the original question.
did you learn how to solve first order linear differential equation
Mhm.
rewrite it to dy/dx = first then use substitution
Give me a second to get my scrap paper real quick.
since i already wrote it down before
found it
i'm checking the first part before concluding the ODE, but it doesn't have anything wrong
think you need substitution to make it seperable
u-sub for the integration part is like the same though
since i already consider u=-y already at the tabular part
@gusty flume Has your question been resolved?
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$\dv{x} \tan^{-1}(x) = \frac{1}{x^2+1}$
ann.in.a.teacup
Is that just something I’m supposed to memorize?
you can figure this out by differentiating both sides of x = tan(y) and doing some rearrangement shit -- but also this should be on your formula sheet anyway
Is there no explanation behind it?
Hmm
there IS an explanation
Ohh ok ok then
Then I won’t bother highkey don’t wanna know💀🙏
Thanks for the help
.close
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genuinely lost
square both sides
why can't i square every part and get (7-4x)+(3-2x) = 1
that ends up at 6x = 11 and it's not a valid answer
artemetra
what
,tex .wrong square
Bonk
$(a+b)^2=a^2+2ab+b^2$
Bonk
what are you guys doing
$(a+b)^2 \neq a^2 + b^2$
loopyloop
square both sides
i showed you an example
you can't individually square it
it will be incorrect
Cuz you typed that it was your idea
you're telling me to isolate one radical and square both sides that way
i am so tired
Yes
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how to calculate dna share with my cousin?
sir this is a math server
LMFAO

this needs to be a sticker
pls
im begging
can i ping the mods
or i do i get ban for thta
do not
😔
they will not add this as a sticker
too good to be missed out
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do you have a real quesiton?
if you kiss your cousin you share 100% dna, happy?
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can anyone double check my work?
Looks correct to me.
looks good!
did the calculations for this one my calculator because for some reason it wasnt letting me input fractions as the answer. Hoping thats just an issue with the question lol
@runic pumice Has your question been resolved?
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what's the general formula to calculate t for any given number based on the pattern in this table
or at least how do i solve it
need more context to be sure, but t=log2(T)
alright i was told the answer was simmilar to y = $5 * 1.5^n (this was another equation from the same topic)
I havent done much with log yet 😭
yeah
a is the number at n=0, and b is the multiplier change between n
so here it's a=1 and b=2
so it's t=1*2^n
okay I got it now but where did you get 1 and 2
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Am I going insane? If f(5) outputs 3 and f(3) = 5 how is this turning out incorrect?
Teacher is a dumass mby
😭 😭
Maybe f(5) doesnt exist?
What grade is this?
its college pre calc im a freshman
i just started so theyre reviewing composition of functions
Try 4 for the meme
didnt work but thanks for the idea
Real madrid typa robbery
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can someone check my work? not just the numbers, but preferably any minor issue that might get points taken off
@tropic skiff Has your question been resolved?
!helpers
To ask for mathematics help on this server, please open your own help channel or help thread. See #❓how-to-get-help for instructions.
<@&286206848099549185>
the first 3 sections look about right
i dont see anything particularily wrong lol
Thanks!
Wait didnt you say youre taking this in the next unit
yeah we did this today lmao
^
makes sense lol
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okay someone PLEASE explain how i can find the height of this triangle
do you know the triangle area formula?
a=1/2bh
out of those variables, which ones do you know? which ones don't you know?
i know b = 5.9
@midnight scroll Has your question been resolved?
any other variables that you know?
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Could some one please help explain method of joints please?
@vernal flame Has your question been resolved?
@vernal flame Has your question been resolved?
@vernal flame Has your question been resolved?
<@&286206848099549185>
- find external reaction forces
- draw an FBD at each joint consisting only of the external forces and the internal forces of the ties connecting to that joint
@vernal flame Has your question been resolved?
Method of joints
You basically first find global equilibrium, so do your support reactions and such
then, for each 'pin' just where two members meet, you want to find one where you have at least one known force, and then just solve for the other forces.
So, in this situation, you can start with joint A and find
FAB and FAF, then move on to the second joint with this information, id personally pick joint B, but you can also pick joint F. Keep doing this for all joints.
This smells like a Hibbler Statics problem
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how were these relationships derived?
@bleak arrow Has your question been resolved?
is this from physics or vector calculus
looks like differential length elements in different coordinate systems
engineering textbook
yes, how did they derive them
i can explain the cartesian/rectangular one but i’m not too sure about the other two
can we derive them through parametrization?
isn't dl = T dt?
= r'(t) dt
or is that for cartesian coordinates only
ye that works for cartesian coordinates since dL is just the derivative of the position vector
but for cylindrical and spherical, the basis vector change with position so it's not as simple as just differentiating r(t) like in cartesian
sorry but i barely have any knowledge about spherical and cylindrical
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why did you not react to this 😭
it wasn't like this before lol
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what do i do
there you go
yea 👍
do i post the question again
yea sure, i'm sure someone would help you
how are these derived?
@bleak arrow Has your question been resolved?
arc length formula $s=r\theta$
cloud
@bleak arrow Has your question been resolved?
the complete way is called the Jacobian where you write all the coordinate conversions from x,y,z to angle coordinates, put all the derivatives in a matrix and take the determinant. the quick and dirty way is just drawing a tiny bit of space from a small change in radius and angle and approximating the side lengths of the "cube"
er I guess for dL specifically it's just like chain rule, you can convert with stuff like dr = (dr/dx dx + dr/dy dy + dr/dz dz)
@bleak arrow Has your question been resolved?
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The base of a solid is the region bounded by the graphs of y = root x and y = (1/8)x^2.
a. Find volume if the cross sections are semi circles on the x -axis
b. find volume if the cross sections are equilateral triangles on the x-axis
i am super confused on how to get this set up, but once it’s setup i know i can integrate it
for part a how do i find the radius
vertical distance between the curves
i think
given that it revolves around x axis right
i don’t think this is revolving
oh
but
since they're both
functions of x
then it's dx
therefore yeah
it is
vertical distance between the curves
would be your radius
mb diameter*
radius would be half of that
it’s not necessarily a solid of revolution
yeah
ik that area = 1/2 pi r ^2
but in my notes i just what what r =, and i have no idea how i got there
i still believe the radius is half the distance between each curves
so
(rootx - x^2/8)/2
wait i think im doing it
nvm
i got that completely wrong
ok
did algebra wrong that’s all
.close
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pls help
hmwk pls, let n be positive integer
prove that there is no solution for 2^{n+3} | 3^n +7 exists
You mean that no n exists such as 2^{n+3} | 3^n +7 ?
yes dat
Thanks
induction?
no weak proofs pls
what
do it
modulo 3 implies n must be even
ik
leads no where
tried playin with 9^k + 7 = (1+8)^k + 7 = sum binom(k,i) 8^i + 7 mod 2^{2k}
i go sleep, i wake up pls make proof & ping me, night night
maybe in your dreams that happens 
no weak proofs no induction or zesty goofy ahh proofs, wont bother readin
xddd ur tripping
Induction is weak ?
ye
How high are you today 😄 ?
use axiom of choice & p-adics
that will get job done night night goofy ahhs
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is the first line not wrong here?
what a name in a math server
im getting $[sec^2(xy)]x\dv{y}{x}$
gamer75431
how so
you remember product rule?
dont we take the inside argument after taking deriv of tan
you need to use product rule to differentiate xy
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is anyone familiar with r studio?
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Can anyone explain to me a clear definition of a gradient vector in MVC
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i know this is a question of physics but can anyone help me in this ?
<@&286206848099549185>
lenz' law
when the north pole comes closer to the ring
magnetic flux is increasing but the ring does not like that so it opposes that by generating its own magnetic flux in the opposite direction (causing an anticlockwise current)
try figuring out when the magnet is moving away from the ring
@steel plank Has your question been resolved?
then it should generate current in clockwise direction
indeed
but when magnet is passing through the coil after sometime the coil will interact with south pole and clockwise current will be generated so answer should be D
but ans is C
@wispy oyster help
ah I see, the question is only asking what happens when the magnet is brought near to the ring
it is not asking what happens when the magnet is pushed away from the ring
damn i noticed one thing
the loop is attached to the wall
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We draw five slips from a hat with each slip labelled 1-100. Each time we draw a slip, we can label it "largest," "second largest," "third largest," "fourth largest," or "fifth largest." Our goal is to maximize the chance that these five numbers we pulled are in exact order as labelled. Describe a strategy that we could do and provide estimates of the probability that that strategy would be successful.
as in, we draw these slips one at a time and we have to give each one a label before we draw the next?
yes i think so
it was given to me in english
ok
well there is kind of a stupid strategy that seems to just be intuitively the best possible
for the first slip, assign it one of the 5 labels according to which of the intervals 1-20, 21-40, ..., 81-100 it falls into
thats kind of what i was thinking too
but how would i estimate the probability this wwould be successful
is where i got stuck
A very rough estimate is just finding the probability of drawing 5 labels 1,2,3,4,5 in the right order
that would just be 1/120 no?
Exactly. I imagine that's a low estimate
I'm sure better can be done, I'll think on it
haha yes thank u very much
Or no, wait, I didn't get my idea right. Instead, let's say we can draw from 1,2,3,4,5 with replacement. Given we do 5 draws, what's the probability we get one of each?
I mean only from the labels 1,2,3,4,5
ohhh
That one is 120/5⁵
I imagine that's like drawing from the intervals 1-20, 21-40, etc
You have to draw from one of each interval
I'm ignoring cases like drawing 19 and 20, so this is still a rough estimate
But yeah, I think it's a bit higher than 3%
that makes a lot of sense
okok yeah but it gives a strong rough estimate
gotcha
thank u very much
Again I wonder if better can be done
mhm
good point
i think
honestly ive thought abt this for almost an hr now so that much is good progress lol
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Hello, I'm trying to prove the following question:
You are given the two equations f, g : (0, π/2) -> R for which the following statements hold:
|g(x) - g(y)| <= (x - y)^2 for any x, y in (0, π/2]
g(x) = f(x) * sinx
f(π/4) = sqrt(2)
Prove that:
the equation of g(x) is constant for x in (0, π/2]
I've tried a lot of things but none of them seem to work. I need a push in the right direction, thank you for your time.
@junior whale Has your question been resolved?
Show your work, and if possible, explain where you are stuck.
ill do that rn
ill show something that i tried
i didnt arrive at a contradiction, so i couldnt prove that g(x) is in fact a constant function
and not a function where g(x) can be greater than or less than g(y), for some x in (0, π/2] and some y in (0, π/2]
@junior whale Has your question been resolved?
prove that g'(x) = 0
for any x in (0, pi/2)
$|\frac{g(y)-g(x)}{y-x}| \leq |y-x|$
Goëtia
then : $\lim_{y \rightarrow x} g'(y) = 0$
Goëtia
u can then deduce than g'(x) = 0 , thus g(x) = c => g(x) = f(x) sin(x), plug x = pi/4 , u got what u need @junior whale
thank you
it does indeed come out that g'(x) = 0
ill close this then

tysm~
how do iclose
!close
.close
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.resolved
.resolve
why hasnt it gone back?
there arent many free channels left, i wouldnt wanna inconvenience anybody
.reopen?

not it will be free'd soon @junior whale
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how do i do this? a is part 1
ik i forgot the rotation above origin at angle theta for a but idc ab that
also ignore the bottom issa diff q
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@kindred mauve Has your question been resolved?
@kindred mauve Has your question been resolved?
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whats the ques?
OP?
original poster
Could someone solve this plesse?
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
we won't solve this for you, but we can see what you've tried and give you pointers for how to proceed
if you are really completely absolutely stuck without even the smallest idea that's still ok (but tell us so)
@long drift Has your question been resolved?
wow ok hold on
ok i can see you are on the right track (and also i have made a mistake in my own solution) but this can probably be written a little better
so alright our goal here is obviously to solve each one of the inequalities to eventually take the intersection of their solution sets
Yes!
for inequality II, you've got it broken down into sin(x)(2cos(x) + 1) ≥ 0
so what i would do here actually is plot its solution set on one circle rather than breaking it down into two
easier to show what i mean so let me sketch a pic
something like this
this is kind of an extension of the wavy curve method to a circle
the way i'm using it, inside the circle means negative and outside means positive
& i don't care much for it being to-scale radially, but all of the crossing points are explicitly marked here in green
0 and pi from the sin(x), 2pi/3 and 4pi/3 from the 2cos(x) + 1
so then i see for inequality I you decided to break it into two cases based on when the denominator was positive vs negative
wait actually
do you understand what im suggesting for II
i wanna make sure we're on the same page here before i move on to I
impossible huh
well let's just keep going with inequality I shall we?
so what i would do here is more or less follow you and first rewrite it as $\frac{1 - \sin(x) - \sqrt{3} \cos(x)}{\cos(x)} > 0$
ann.in.a.teacup
then also multiply both sides by $-1$ just to have a bit less minus signs to deal with, so $$\frac{\sin(x) + \sqrt{3}\cos(x) - 1}{\cos(x)} < 0$$
ann.in.a.teacup
and then also do the same thing you did with the R-formula (or whatever else you wanna call it) and reduce to $$\frac{2 \sin(x + \pi/3) - 1}{\cos(x)} < 0$$
ann.in.a.teacup
Right!
so when it comes to doing the circular wavy curve method, the denominator changes sign at 3pi/2 and pi/2 while the numerator changes sign at pi/2 and 11pi/6
which i believe you also worked out in your work
sin(x + pi/3) = 1/2 etc.
Yes!
the upshot is that at pi/2, numerator and denominator both change sign, so the sign of the fraction does not change there
Okk
so we get this kinda thing
i've got colored pens on me so i am using two different colors on one circle
and i've also put hatch marks of the relevant color in the regions where each function is the right sign
if you dont have colors what you could do is draw a number line from 0 to 2pi that's like your circle unrolled into a straight line
and plot the intervals for each inequality that way
and then take their intersection
Yes yes i did that
so anyway you can see there is no overlap here
that's why the solution set is empty
@hazy cradle what's with the skull react?
no, II is perfectly fine as far as i can tell.
nvr thought shit wud be that complex...
i think your biggest mistake was trying to do this all symbolically rather than using unit circle diagrams and keeping yourself in check visually
with rational inequalities you can sorta get away with this, but with trigonometric ones it is much much harder
Alright!! Thankss!! Ill check maybe better thank you very much!
Yes this one is tricky!
it's trigonometric inequalities, stuff is complicated with these
and this system in particular imo is quite beefy
Yess thank yiu very much!
like i nvr solved it with such type of a graph
do you know the wavy curve method
like for non-trigonometric ineqs
this thing i'm doing here is an extension of that to trig
which i think is pretty elegant
damn
@long drift do you have anything else to ask for now? or are we good
you can .close the channel if you're done
it looks the same in terms of the overall idea but there is a lot more table-bashing and unintuitive visuals for my taste
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We are given a function ft(x)=tsin(tx) and are told that two neighboring zero points have tangents which touch at an angle of 28 degrees for a certain value of t
this is what I did, but I do not think that it is correct
can someone tell me why I am wrong and how to fix it?
(my approach btw is that if the angle of them together has to be 28 degrees and they have the same slope then the angle with the x axis has to be half of that at 14 degrees)
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We are given a function ft(x)=tsin(tx) and are told that two neighboring zero points have tangents which touch at an angle of 28 degrees for a certain value of t
this is what I did, but I do not think that it is correct
can someone tell me why I am wrong and how to fix it?
(my approach btw is that if the angle of them together has to be 28 degrees and they have the same slope then the angle with the x axis has to be half of that at 14 degrees)
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@pure mesa Has your question been resolved?
the angle (1/2) * alpha being 14 degrees gives you the slope. so find the equation of the tangent line and solve for the slope by finding the angle beta.
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is the inverse wrong here?
my teacher wrote y = loga(x)
where exactly there's like 10 things written on that screenshot
she said "we know that the invrse of y = a^x is y =loga(x)
this is correct
but then right beside that she wrote what i think is right?
yeah
shouldn't it be loga(y) = x
this is the work that proves ^
how
isn't that not what she wrote here
i feellike this one is right
x and y are just dummy variables
the inverse of y = 2x is y = (1/2)x
you can just think of it as convention to write the inverse function of $y=f(x)$ as $f^{(-1)}(x)$ as a function of the same variable $x$
riemann
im still confused kinda
how can they both be right when they are saying different things?
isn't y = loga(x) the same as a^y = x
again, the inverse function is, by convention, written in terms of the same variables y = f^(-1)(x)
do you agree that $f(x) = 2x$ and $f^{-1}(x) = (1/2)x$ are inverses of each other?
riemann
y = 2x
x = 2y
y = x/2
so ye
great. same logic applies to $y = a^x$ and $y = \log_a(x)$
riemann
it's right there
yeah
that one makes sense
i understnad ur saying its js convention for the other
but i dont get what you mean rly cuz dont variables have to serve a prupose
like how can x and y be interchangeable
when she writes y = loga(x)
did you agree with this or not?
yes
"ye" sounds like yes
i do
you swapped x and y there
so why are you asking this
so then this isn't the inverse?
how can log_a(y) = x and y = loga(x) both be inverses of y = a^x
i understand how log_a(y) = x is the invrese
but if that one is the inverse of y = a^x, then how can the other also
you wrote this right?
yes
what
from which she js swaps the x and y
in the screenshot of log_a(y) = x, is this just the expression of y=a^x as a logarithm while the line log_a(x) = y is the inverse of y=a^x
$y = a^x$ implies $\log_a(y) = \log_a(a^x) = x$
riemann
no inverses happening ^
$y = \log_a(x)$ is telling you that the inverse of $y = f(x) =a^x$
is $y = f^{-1}(x) = \log_a(x)$
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Hey I'm working on solving DEs by substitution and i've been given a bernoulli equation. I'll show the steps i've taken so far up to where i've gotten stuck
\begin{align}
\dv{y}{x}&=y(xy^4-1)\\
\dv{y}{x}&=xy^5-y\\
\dv{y}{x}+y&=xy^5\\
n&=5\\
u&=y^{1-n}=y^{1-5}=y^{-4}\\
y&=u^{-\frac{1}{4}}\\
\dv{y}{x}&=-\frac{1}{4}u^{-\frac{5}{4}}\dv{u}{x}\\
-\frac{1}{4}u^{-\frac{5}{4}}\dv{u}{x}+u^{-\frac{1}{4}}&=xu^{-\frac{5}{4}}\\
-\frac{1}{4}\dv{u}{x}+u&=x\\
-\frac{1}{4}\dv{u}{x}&=x-u\\
\dv{u}{x}&=4(u-x)\\
\end{align}
lILi
steps 1-3 are manipulating it into proper form
steps 4-7 are setting up the substitution
step 8 is applying the substitution
steps 9-12 are manipulation
and by proper form, I mean
$$\dv{y}{x}+P(x)y=Q(x)y^n$$
lILi
anyways, i'm not sure where to go after step 12
linear ode
your goal with bernoulli odes is typically turning it from bernoulli ode into a linear ode
which is what you've done here
then you'll have u(x), and you can replace u with y
So, if i've understood correctly, I do this and then work things out?
\begin{align}
u&=y^{-4}\\
\dv{u}{x}&=-4y^{-5}\dv{y}{x}\\
\dv{u}{x}=4(u-x)&\Rightarrow-4y^{-5}\dv{y}{x}=4(y^{-4}-x)
\end{align}
lILi
errr
my point was more solve the linear ode
this was the whole point of getting it down to a linear ode
so solve the linear ode in terms of u, i.e. get u(x)
then using the fact u=y^-4, you get u(x)=(y(x))^(-4)
In this section we solve linear first order differential equations, i.e. differential equations in the form y' + p(t) y = y^n. This section will also introduce the idea of using a substitution to help us solve differential equations.
ah, my bad
I realise how I got confused about your explanation. Anyways, the issue i'm having is just, algebraic manipulation, trying to solve for u
its a linear ode
In this section we solve linear first order differential equations, i.e. differential equations in the form y' + p(t) y = g(t). We give an in depth overview of the process used to solve this type of differential equation as well as a derivation of the formula needed for the integrating factor used in the solution process.
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quick questiion, why is integral calc chaging the 2-3x? I'm guessing its the absolute value but im not sure why
so abs value of 2-3x would also be correct?
yea
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how to do 49
it is helpful to first do a similar problem, but in 2d instead
well, that or you can just bash it.
did you do 48?
48 is harder, no?
no
if annyone can help me with this pls do
the question involves distance between points
so consider applying distance formula
please claim your own channel as this is occupied #❓how-to-get-help
@remote elbow Has your question been resolved?
can u write it out bro
how to apply it
to find the set
have you applied the distance formula before?
@remote elbow Has your question been resolved?
yes
im not at home now
i can’t do it rn
@remote elbow Has your question been resolved?
@remote elbow Has your question been resolved?
I think you need to find the plane equation between 2 points
yea
so i got midpoint
now how to get plane
@remote elbow Has your question been resolved?
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I'll send my work in a second
Hi
Oh I did, that's not good but thanks for letting me know
you mean still not the right answer?
No as in it's not good I typed it in wrong
ah ok
Unfortunatly
try 54.7164
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for systems of equations how do you choose whether to eliminate y or x
Personal preference
Or
Depends on the system as well.
Guass!
Let's say you have a system like:
100x+y=0
-99x+y=3
You're obviously eliminating the y here.
For the real ones (linear fellows)
Yeah, both of these involve prime numbers. Just multiply out the ones that seem smaller.

I would personally eliminate the y first
just relised i did the second part wrong lol
tbh i think for like school it's probably easier just to do lots of practice rather than trying to optimise eliminating x or y, i don't think it makes too much of a difference here
Go the unkindly path, eliminate only in the most algebraically confusing and computation intensive ways! (For the real ones)
i know i thought it made a difference
it doesnt
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obviously in some examples like ^ you probably wanna eliminate y instead
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there are 15 points as in the picture. what's the probability of 3 randomly chosen points NOT being colinear?
now here's the thing
I got 1223/1365 while the correct answer is 1221/1365
so that means I'm off by 2, which means I can already be proud of myself lmaoooo
idk if I did it right (well obviously not since I'm mistaken) but I started by writing down all the ways you could choose the points that are colinear (so that I can subtract later in order to get the ones that aren't colinear)
and idk if there's a faster (and more importantly, correct) way of doing it
yeah
oh wait wait wait I got one more way
but that still leaves me with 1 way I don't have
well no
lol
how do you get 0.5 in odds
there are 2 with slope 1/2
yeah I got these
the extra one I just found is vertical
actually I confused myself bc of the fractions lol I originally needed 4 more ways and now I need 3
you got the horizontal ones I suppose?
I can show my solution
- horizontal lowest layer
5*4*3 - horizontal 4th layer
4*3*2 - horizontal 3rd layer
3*2*1 - diagonal with 5
2*5*4*3 - diagonal with 4
2*4*3*2 - diagonal with 3
2*3*2*1 - slope 1/2
2 - vertical
1
and all the ways are 15*14*13
and calling it "with slope 1/2" is very smart lol in my notebook I called it diagonal double jump lmfao
why are you multiplying diagonal with 3 by 4?
bc there are 4 ways you can get them
thank you lol
I only see 2
I'll draw it
hrizontal and verical
oh wait
you're right bruh
I also included the ones that are already in diagonal with 4 bruh
do you double count the vertical?
...
no, why?
I guessed that you divided the whole thing by 2 as to not double count right-left and left-right.
and you cant do that with vertical/horizontal
I'm confused
well when you pointed out the diagonal with 3, I just swapped the 4 at the beginning for a 2
and that's it
my bad. Thought you counted in a different way
and 2*3*2*1 is indeed 12 ways that I "lost"
wait... 3 diagonal should be 1 if we don't care about order...
2457 instead of 2445
do we care about order?
yeah... here is 4x3x2x1?
well if I scrap these too then there's gonna be a whole lot more I missed lmao
but I changed it for 2*3*2*1 like I told you
I'll edit the message maybe
yeah, I just looked back, my bad
no worries
but 3x2x1 cares about the ORDER in which we choose the points
and that's goes for all the other ones aswell. Is that what the problem stated?
it doesn't really state anything
just "3 randomly chosen points. what's the probability of them not being colinear"
It doesn't matter(I think). You just have to d the same for the calculation of all points. And you do that
but for example if you chose 2 ones from the left diagonal "line" and 1 from the top of the right diagonal "line" then they wouldn't be part of the same line, so I'm choosing to count them separately as 2*3*2*1
idk if that's about order
well for some reason my solution is wrong and I'm now missing 12 ways
huh?
what's c and p
that's what I thought. But both should cancel since we're talking about probability
also 455 is basically 1365 in the fraction
bc 1365 is like the expanded fraction
the correct answer is 407/455, but since I got 1223/1365, I multiplied it by 3 to figure out how wrong I was lmao
and 407/455 is 1221/1365
I still don't know what these stand for
I don't know n but c is for choose
those shouldnt matter for the premise of this question
aight
where does 2730 come from?
15x14x13
you ordered everything except the lines with slope 1/2 and the vertical line
so slope 1/2 should be 2 * 3 * 2 * 1
and vertical should be 3 * 2 * 1
which gives the the given answer

ohh, ok
So, we have:
horizontal lowest layer
5x4x3
horizontal 4th layer
4x3x2
horizontal 3rd layer
3x2x1
diagonal with 5
2x5x4x3
diagonal with 4
2x4x3x2
diagonal with 3
2x3x2x1
slope 1/2
2x3x2x1
vertical
3x2x1
and all the ways are 15x14x13
@rustic jetty
it isn't tho
read after
OH BRUH I'm a total dumbass
idk why I didn't count them like this even tho I did it with everything else bruh
thank you so much
.close :)
np lol
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It was fun while it lasted @pallid stream @rustic jetty
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what is the question asking?
idk what f^6(0) is referring to
the 6th deriv when it is equal to 0?
yes
Yep
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This is my explanation of why its true that the columns of an n x n matrix A are linearly independent when A is invertible. Is this a good explanation?
what's the clown emoji for
Mey doesn't like my explanation at all
i would say theres a few problems, firstly what is a pivot ? is this just some term i havent come across and has a defined meaning or did you make it up
if you made it up then you need to define what it is
its a term for the class
i thought pivot was a generally well-known term
it is
The pivot or pivot element is the element of a matrix, or an array, which is selected first by an algorithm (e.g. Gaussian elimination, simplex algorithm, etc.), to do certain calculations. In the case of matrix algorithms, a pivot entry is usually required to be at least distinct from zero, and often distant from it; in this case finding this e...
ah nws then
i would also like to see some more reasoning as to why the rows being linearly independant means the columns must also be
can be as simple as just saying det(A) = det(A^T) tbh, but i think it needs to be in there
i never mentioned the rows being linearly independent though
oh wow yeah i cant really
the identity matrix pretty obviously has pivots in every column imo
really dont know how i read that so wrong ahah
its ok
yes the explanation is fine
even the last statement?
yeah sorry again for misreading so badly LOL
im worried that i made a jump from rref(A) invertible -> A invertible
well presumably you are allowed to use that row reducing doesnt change linear (in)dependence between columns
Not sure i was explicitly told that in class
Not that I don't trust it's true
More that I think its up to me to justify that
the whole point of row reducing is basically that fact
Yeah and it makes sense given the idea of elementary matrices
or phrase it as solving the linear system
same solutions <=> same dependencies between columns
Oh right
I can easily prove that Ax = 0 implies x = 0
Which would mean the columns of A are linearly independent
yes
Thank you! I appreciate it
yw
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,rotate
Couldn't find an attached image in the last 10 messages.
I'll probably only need help with part 1
Hint: $\frac{x^2}{9}+\frac{16}{x^2}=\left( \frac{x}{3} \right)^2+\left( \frac{4}{x} \right)^2=\left( \frac{x}{3} -\frac{4}{x}\right)^2+\frac{8}{3}$
gotta admit though, that one may be pretty hard to figure out
@viscid wagon
TargetVN
sry, it's this instead
@viscid wagon Has your question been resolved?
So the minimum value of A is the minimum value of x/3 - 4/x +8x/(x2+12)?
you can do that, or just do the very obvious substitution u = x/3 - 4/x
do note that with this substitution, 1 value of u will output 2 values of x
Oh bruh I'm stupid 
but we can't gaurantee that those are real, can we...
nor can we gaurantee that they are double roots
examine u(x) = x/3 - 4/x through u'(x)
ohh, smart
,w 3A^2-32=0
seems like it
Huh how'd you get that quadratic
u^2 + 8/3 = Au
which is just a quadratic
Oh
since 1 u gives 2 x, the quadratic must have 1 root only
For part ii is it just checking if the AM-GM inequality holds
i mean since we have found what is A, we can just find u
then find x
no need some fancy stuff here
also the word "minimum" is kinda deceptive lol, theres only 1 value of A satisfying the problem after all
How are you able to see all this 
it all started from this
that one is obvious for me but not for anyone else
then just kinda work from that point and the solution pops up over time
