#help-23
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Is 'throwing a fair die, each number has a 1/6 probability chance to be the outcome' a model?
Model is a conjecture
A mathematical model is an abstract description of a concrete system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in applied mathematics and in the natural sciences (such as physics, biology, earth science, chemistry) and engineering discip...
Mactutor has no entry on the history of "model" https://mathshistory.st-andrews.ac.uk/Miller/mathword/m/
There are mathematical models in music!
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oh it took me a minute
the names are written vertically @mystic timber
e.g.
I
D
A
H
O
which, if you flip it, becomes
I
ᗡ
A
H
O
@mystic timber Has your question been resolved?
So the answer is Hawaii supposing all the words are written capital
@fickle pendant
yes
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Trapezoids area is 594 the hight is. 22 the difference between the parralel sides is 6 need to find both of the parralel sides
he is lost
you should have let him either try to state the formula or tell me he doesn't know
he wasn't answering for 3 minutes
3 minutes is not a stall
and even if he was not answering for 30 you should not have spoiled it
if op chooses to stall and let the channel time out, that's his choice
or if he has to go for something urgent, idk
okay then say the formula
A+b/2*h
missing parentheses
(a+b)/2 * h
but ok alright fine
you can find a+b from here
and the problem tells you a-b=6
A+b equals 2h no?
incorrect.
Wait
$S = \frac{a+b}{2}\cdot h \ h = 22, , S = 594 \ a+b = ; ?$
Ann
2s/h?
I can make a system right
yes exactly
Ok ill do it
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*A tower has four asymmetrical wings.
Determine the relationship for the number of blocks+1 needed for the squares of the height+1 if you know the number of squares of the height.
Then show by induction that an=n(2n−1), n=1,2,3,...*
Does someone actually understand how to solve this?
"Determine the relationship for the number of blocks+1 needed for the squares of the height+1 if you know the number of squares of the height. "
Particularly, what does this even mean?
What does it mean that a tower has a wing?
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What is a model?
Context?
Throwing a fair die, or tossing a coin.
In those cases a model would be coming like a way to represent the outcomes of those events mathematically
Or the probabilities of things occurring
1/6 and 1/2 are models
A probability model for a coin toss looks like this.
Probability model for fair die roll:
import random
num_trials = 1000000
num_heads = 0
for i in range(num_trials):
coin_toss = random.choice(['H', 'T'])
if coin_toss == 'H':
num_heads += 1
probability_heads = num_heads / num_trials
print(probability_heads)
Is this Python snippet still a probability model?
@south sparrow Has your question been resolved?
Thanks @final halo , this is great, now I can create a model!
import random
print(sum(random.choice('HT') == 'H' for _ in range(10**6))/10**6)
| |
H | 0.5 |
|_______|
| |
T | 0.5 |
|_______|
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can anyone please explain to me when doing implicit diffrentiation where does the dy/dx come from
Chain rule on y
wouldnt it just be 3y^2
We can think of d as a little bit of something. y depends on x, so if we adjust x by a tiny bit, y is changed by a tiny bit.
This can be written, by adding dx to all the x terms, and adding dy to all the y terms.
where does prime y come from
Chain rule
k i understand that
What is prime y?
y'
Would you know how to find the derivative of [f(x)]^3?
Say we have y = x^2, the derivate of this is y + dy = (x + dx)^2, where we adjusted the y and x values by a little bit.
3F(x)^2?
You're forgetting chain rule. Again
@covert kiln are you familiar with what chain rule is?
yh
Do you know how to use it?
u bring power down and diffrential and times it by the origanl and subtract 1 to the power
I think that's the power rule
That's power rule..
If you mean d(x^n) = n*x^(n-1)
@covert kiln read up on chain rule. You need to understand it to understand implicit differentiation
that times
yh taht what i said
OK, really not great to use x as both a variable and to mean times
That's an example, yes
But you don't seem to understand how chain rule applies here. Which tells me you need a thorough review of it before we can proceed
Can you explain it in simple terms please, because these concepts show something dead simple in complicated language.
True, that's an example of using the chain rule with the power rule. In general, the chain rule applies when you compose two functions f(g(x))' = f'(g(x))*g'(x)
the question taht im asking?
isnt that prodcut rule?
If it helps, remember that y is a function of x, so you can write it as y(x)
To explain things to you, if someone knows the simple thing behind the complexity.
And to me!
No the product rule is (f(x)*g(x))' = f(x)*g'(x) + f'(x)*g(x)
yh mb but i was only taught chain rule via power rule
OK, you're going to need it in other cases too like sin(x^2)
This is incorrect. Again. You are ignoring chain rule
$[f(g(x))]'=f'(g(x))g'(x)$
SWR
can u give an example with numbers please
if we diffrentiate x^3 we just get 3x^2
Try finding
(sin(x^3))'
3x^2cos(x^3)
?
how does this help with my orgianl question
You asked for it?
oh ok
i dont understnad how it used for y^3 tho
and how it ends up being 3y^2 dy/dx
Let y=f(x) then apply chain rule
Let $f(x)=x^3$ and $g(x)=y$
SWR
f(X)^3 =3F(x)^2
Try this one.
im lost on the fact that there 2 diffrnet functions
And apply as written here
kl il try
[f(y)]' = f'(y) (1)
Nope
im so lost on that formula
$g'(x)=y'$
SWR
y'=1
I would review it in your book if I were you
False
That would only be true if $y=x$ (plus some constant but I'll ignore that)
SWR
our teacher didnt teach us that formula
Unknown. That's why we leave it as just y'
is it equivalent to dy/dx
I highly doubt that. It's necessary for this stuff. Ask your classmates if they have seen it
Yes. It's just shorthand notation
😭
our teacher shows us shortcut
why isnt there dy/dx when we diffrentiate x^3

Because there is no y in x^3
but there no x^3 in y
You are differentiating y^3 though, not y
Okay, try this:
What is derivative of $[\sin{x}]^3$
if we diffrnetiate y^3 we get 3y^2 dy/dx but there no dy/dx for diffrentiating x^3
SWR
that what 1 of my classmate said
It's mostly right. But it's kind of a word soup
Correct
wdym word soup
yh i dont understand why tho im copying that from the anwser
It rambles on a bit too much
3cossin^2
can u give me a simple explaination
This is correct. Suppose y=sin(x). What is y'?
dy/dx means "differentiate y with respect to x"
what does that mean tho
can i also diffrentiate y terms?
im confused with the wording with things0=sdo[kdasdasd
It means to find the derivative of y with respect to x
Yes
Yes
dy/dx also means a tiny change of values, it is a slope value. ∆y/∆x
As we change x a little bit, y changes a little bit with it.
is the statment i said true
And I think in your original equation we write x^3 + x + y^3 + 3y = 6 as x^3 + x + u = 6
Sorry, which statement?
@covert kiln Has your question been resolved?
What might it feel like to invent calculus?
Help fund future projects: https://www.patreon.com/3blue1brown
An equally valuable form of support is to simply share some of the videos.
Special thanks to these supporters: http://3b1b.co/lessons/essence-of-calculus#thanks
In this first video of the series, we see how unraveling the nuances of a simp...
There is a video on chain rule as well, in this series.
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yo
if we have a^k = x mod t
and we have a and x and t
when do we know that this will cycle
for example(every fifth k)?
Please don't occupy multiple help channels.
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!1c
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Find the inflection point in the curve f(x) = | x³ - 1 |
When I differentiated again the function became x6
So x6 =0
Then x = 0
But when I looked at the answers it turns out there are 2 values
{0 , 1}
How did x become 1?
Ok should I ping helpers role?
after 15 minutes of waiting you can ping the helpers role once
Ok
.
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I don't know how to find the range of values for this problem y=1-sin²(x)cos²(x)
start by finding the range of values for sin(x)cos(x)
Hint: sin(x)cos(x) = 2*sin(x)cos(x)/2
It's y=[-0.5;0,5]?
yeah good job
should be pretty straightforward from there
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That's a second derivative test
Solutions to part a
nono like
how is it certain that when plugging in those values to the second derivative that the value of the second derivative is >/< 0
is it to do with 0<=x<=L
/<?
when u put L/2 into the second derivative
how do u know that the second derivative is negative in that case
You calculate it
Get the second derivative, plug L/2 into it
They did calculate the second derivative above your circled part
oh ye brainfart sry
i missed the carry through of L on 6xL which made it impossible
thanks
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I'm having trouble with the substitution method, i think i just have a misunderstanding of something simple
please could you hlep me with this:
oh wait
i think i get it
.clsoe
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✅
i didnt lol
oh wait
maybe i am
sorry
one second
was getting confused with this now writing it out
slowly making sense
is this the correct preliminary steps for the question?
@wheat apex Has your question been resolved?
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I wanna solve this problem but when I try to solve it my answer does not match the answer given by the Google
√x +√x-64 = 16
(√x +√x-64)^2= (16)^2
x+x-64=256
2x-64=256
2x=256+64
2x=320
X=320/2=160
The answer given by Google is 100 where did I went wrong?
sub x=u^2 probably
$(\sqrt{x}+\sqrt{x-64})^2\neq x+x-64$
Crystopher
what a hell
tf
You forget 2ab in (a+b)^2
He did wrongly
its going to be hectic, id recommend you take a term to RHS and then square
that's fucking square formula a²+2ab+b²
? Just say x>0 x>64
Idk
It's getting too hard
First of all square both sides correctly
Let me try it
$\sqrt{x}+\sqrt{x-64}=16\ x+2\sqrt{x^2-64x}+x-64=256\ 2\sqrt{x^2-64x}=320-2x$ do you think you can take it from here?
oh it got cut off
PajamaMamaLlama
Square both sides again nah?
Can you do what @exotic sky said
this is wrong
you wont get solution
the root is going to be annoying
take the rootx or the other term to the RHS
then square
2 times
you'll get your answer
that is the exact same thing I did above?
Agree
Okay like this
√x-64=16√x
16 - rootx
like this
√x-64=16-√x
(√x-64)^2=(16-√x)^2
(√x)^2-2*√x64+(64)^2=(16)^2-216*(√x)+(√x)^2
=x-2x*64+4096=256-32√x+x
√(x-64)≠√x-64
So it is a whole value in itself?
(64x+4096)^2=(224√x+x)^2
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What does Paul mean by normal vector not having to touch the plane?
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How do I start
what have you tried
@fluid holly Has your question been resolved?
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Not sure if my method is right but i think u have to use begger here and then apply probability multiplication theorem
whats that?
i think you gotta consider what happens to the other 9 balls. how they are put into boxes
begger os probability multiplication theorem?
Which 1 u talking about?
begger
its a topic from Permutation and combination, Number of ways to distribute "n" items among "r" ppl
$${n+r-1}C{r-1} $$
Snow
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Snow
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when diffrentiation cant i just rerannge and make y the subject
then diffreentaite and p[lug in 2
if thats possible then do that yes
show your work
k but its kinda messy
alright
if u cant read it i can rewritre
just that last part where you differntiate it please
is that better
i pluged in 2 and i got -11.296
you sure $v'=2$?
The Great D
oh minus 2
yes
still got the wrong anwser 😭
and why do you have it multiplied by 6^x?
oh
cause before i did 2x3^x which equals 6^x
but that was wrong
forgot to change it
let me retry
careful there 2*3^x is not the same as 6^x
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sqrt(x^3) = x^(3/2)
why is this not true
It is true.
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how would i do this
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I'm trying to solve for x but I completely forget how
not really, first add the stuff up
the multiply the added numbers by 39/50 and also multiply the part related with x or sqrt(x)/4 with another 39/50 and add them together
167*39/50?
yea so u have ((167+sqrtx/4)x39/50)+10=170
and then just as i said multiply the 39/50
167*(39/50)+(sqrt(x)/4)*(39/50)
btw stubtract ten from both sides too as we dont want that plus ten there for nothing so we just got 167(39/50)+(sqrt(x)/4)(39/50) = 160
Sorry I'm confused how did you get that
so we multiplied teh parts right?
oh i see what you mean
the 167 is oviously the added numbers 103+14+50
here there is this that can help you: (a+b)*N = aN+bN
If you're multiplying stuff in brackets it's like you're multiplying it with everything inside separately
yup
Okay yeah
now we subtract ten from both sides as we got that plus ten at the end meaning that 167(39/50)+(sqrt(x)/4)(39/50) +10-10=170-10
those plus tens cancel out, and 170-10 = 160
now we multiply the 39 with 167 and then divide by fifty for one of theh parts
Okay
167*39=6513
if we divide it by 50 we get 130.26
now we can subtract frm both sides
and the +130.26 and the minus 130.26 cancel out for the left part while we get 29.74 for teh right side
now, we multiply the sqrt(x) and 39 on the top and 4 and 50 on the bottom
Yep
Alright
Then we divide both by 39?
yup
Okay it's like 152.51
now since we see that the fraction is infinite/very long we just let it be, dont simplify it to anything just let it be
yup, but we wantv exact answers, in math the more precise you are the btter you are
Ok
but since we got sqrt(x) not just x , we can square both sides
Yes I jumped the gun
just leave it there, dont simplify, tahts what you get when you square 5948 and 39
Okay cool
I have another kind of algebra question but should I make a new help thing?
no we can finsih it here its fine
So I should post my other question here?
why not, keep it running, if it tells you to stop we can try another help channel
Okay
ohh, webpages
Nope sry
One sec
It's kind of the same.
This is the formula for calculating HP in my game and it has five variables and I know that if you have four variables you can calculate the fifth variable so I wanted help getting one of the variables to be like what it's equal to.
I also tried simplifying the formula 🙂
((B + I + (√E/4) + 50) * L / 50) + 10 = F
There
my question is, whats te context on this, what do you mean by hp/ hpiv/hpev
horsepower???
Right so that's why I simplified it to this
((B + I + (√E/4) + 50) * L / 50) + 10 = F
Base HP is one variable and HP IV is one variable and HP EV is one variable and Morty Level is one variable
abs value is noot needed when we got square roots, so remove those,
What sorry?
you know those straight lines around the hp ev part?, yea we dont need those
so now we multiply all parts by morylevel/50 which we can call m/50
k why not
I'm trying to flip the equation around so we can solve for HP EV
so hp-ev is not hp*ev, from what ur saying
Correct
oh ok make sense
HP EV is one number
that make it way easier foor me to follow
It stands for health point effort value
you doing pokemon?
Kind of
It's like pokemon set in Rick and Morty
You use different universes mortys as Pokémon
I would rarely dought you would need specific values even in compeetivve or coding
anyways lets continue
Ok
if thats the case we gotta restart, so its easier
Yep
ill write it down in desmos just wait
By the way what did you use to write these
desmos
btw what do you mean by morty level, im familier with gen 1-3 but i dont remeber a morty level?
Well it's not Pokémon it's a different game in the style of Pokémon it's just it's level
ok i see but can that morty level be negative by any chance
what about the hp evs
That can be between 0 and 65535
ok, that amkes it way easier, and heck this game is completly ripping off old pokemon
It's called pocket mortys
It's set in the Rick and Morty universe
Multiverse
And there's only three types rock paper and scissors
Lol
heh, anyway
Lol
Oh Base HP is all one thing sorry about that
I did take the formula and make them all single letter variables if you'd like that
I don't get you, what do you mean by all one thing?
"Base HP" represents a single number
oh, liek its constant like :2, and is always something like 2
Are you familiar with base stats?
So base HP is it's HP base stat
I used to do that a little
yup, i see, but i stilld ont get the problem
Over on the left you have just "hp" and I'm not sure what that's representing from the original image
this?
oh by hp its means what its hp is at what lvl, what evs, while base stats represent its orignal values before calculuation, a morty charector with higher base p, will have more hp than a one with lower base hp, if the evs and ivs and moretylevek are the same
Okay there are five variables
"Base HP"
"HP IV"
"HP EV"
"Morty Level"
"HP" (the final HP stat)
The three instances of HP does not mean those are the same number
Base HP is 170 but the HP IV is 14
Each circle is one variable separate from the rest
yup i just put the base(hp) as its easier to write not cause i thought it was a function
Oh I thought you meant "base" multiplied by "hp"
As if they were two separate things
anyways have a nice day
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s2 = 20, s4=200 in a geometric sequence
s2 = 20, s4 = 200
20=a(1-r^2)/1-r
200=a(1-r^4)/1-r
20(1-r)/(1-r^2) = a
subs
200=20(1-r)(1-r^4)/(1-r)
200=20(1-r^3)
200-200r^3=20
200r^3=180
r^3 = 9/10
is that right?
why is the second eqn 400?
s4=200
I dont understand the sub you did to combine them into one equation. Can you please explain?
@torpid pumice Has your question been resolved?
oh right my bad
yeah, I put the values i got for a into the other equation
<@&286206848099549185> is this right? im pretty sure its still wrong
ok in the sub...
where did the (1-r^2) part go
its part of the expression for a
it should be $\frac{20(1-r)(1-r^4)}{(1-r)(1-r^2)}$ no?
The Great D
oh shit im so stupid
ok wait ill try the whole thing from the beginning
ok
20(1-r)/(1-r^2) = a , 200=a(1-r^4)/1-r
200=2(1-r)(1-r^4)/(1-r^2)(1-r)
200=2(1-r^2)
200-200r^2=2
198=200r^2
r^2=99/100
<@&286206848099549185>
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✅
20(1-r)/(1-r^2) = a , 200=a(1-r^4)/1-r
200=2(1-r)(1-r^4)/(1-r^2)(1-r)
200=2(1-r^2)
200-200r^2=2
198=200r^2
r^2=99/100
<@&286206848099549185>
these are two diffrent eq right'?
ya
CosMo
I believe this is right
This is your question right? (s2=20)
send the original question
yup
geometric series where s2=20, s4 = 200
find r and a
So then where are you stuck right now?
where the sum of the first 2 terms =20
and
the sum of the first 4 terms =200?
yup
$S_2 = a(r^2 - 1)/r-1 $
$S_4 = a(r^4 - 1)/r-1 $
when |r|>1
$(S_4/S_2) = (r^4 - 1)/(r^2 - 1)$
ishigamisenku_
@torpid pumice
omfg
im
so fucking sorry
i didnt even write the q properly
im so sorry
wait no its right
imlosing my mind
YES
sub value of $S_4 and S_2$
ishigamisenku_
don't forget its division
ohr yeah
$10 = (r^4-1)/(r^2-1)$
$10 r^2 - 10 = r^4 - 1$
ishigamisenku_
collect like terms
then $r^4 - 10r^2 + 9 = 0$
ishigamisenku_
okayy
OH
Isn't r^4-1=(r^2+1)(r^2-1)?
i kept trying to figure out where a went n all you just ignored it

yes
bro it makes it slightly easier
when you divide a at top cancels out a at bottom
ye ik
Then isn't it just r^2+1=10 (r!=1)?
then $r^4 - 10r^2 + 9 = 0$ \
let\
$r ^2 = x\$
$x^2 - 10x + 9 =0$\
$=> \frac{10 \pm \sqrt{100 - 4 (9)}}{2}$\
$= \frac{10 \pm 8}{2}$\
$r^2 = \frac{18}{2} = 9 $\
$r = \pm 3$\
or\
$r^2 = \frac{2}{2} = 1 $\
$r = \pm 1$\
r is either 3, -3, 1, -1
expand the top dif off 2 squares

yes r = 3
bru
yes
Can you tell me if this is wrong
realtime
its unclear
\pm
I got r^2 = 9 and 1
if its 1 then (r^4 - 1)/(r^2 - 1) = 0/0 or -1/0
so its r^2 = 9
ah
r^2 = 9
(r^4 - 1)(r^2 - 1) = 10
wait how is it 0/0?
if r=1, -1 in
(r^4 - 1)(r^2 - 1) = 0
(1 - 1) (1 -1) = 0
0*0 = 0
oop i forgot "/"
I dont get you
i omitted the divide sign
this is what i mean
if its 1 then (r^4 - 1)/(r^2 - 1) = 0/0 or -1/0
so its r^2 = 9
r^2 = 9
(r^4 - 1)(r^2 - 1) = 10
@red delta
what about this equtiona
$r^4 - 10r^2 + 9 = 0$ \
realtime
hmm 
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@stable sedge #help-4 message
Why are you multiplying the x coordinates by 2?
Just leave it as such
and then substitute into the equation of the line
and that gives you the coordinates of P and Q
oh wait frick
so $y = x+ k = \frac{(-k \pm \sqrt{-k^2+8})}{2} + k = \frac{(k \pm \sqrt{-k^2+8})}{2} $ if i can add right
$y = x+ k = \frac{(-k \pm \sqrt{-k^2+8})}{2} + k = \frac{(k \pm \sqrt{-k^2+8})}{2}$
ISAVAGE
ok
then would i add the two and divide by two?
please say yes
ok gud
am i trippin $\sqrt{-k^2+8}} $???
oh wait
M(-k, k)???
but i then that would be wrong 😭
hjhmmm
i redid got (-2k, 2k) but also wrong oof
@tardy mango wait how is this right?
isnt it $(x1+x2)/2, (y1+y2)/2$?
ISAVAGE
isnt the 1/2 over the fraction?
wut
oh i forgot k
uh
im trippin lemme look again
nvm it's $\left(\frac{\sqrt{8-k^2}}{2}, -\frac{1}{2} \sqrt{8-k^2} \right)$$
wut u get -k/2??
Civil Service Pigeon
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I'm multitasking so I'm doing this in my head lol
i was too lazy but ??
your intersections are wrong
i thought we are finding the midpoint?
...
cant u simply do that???
the intersections divided by 2?
are they not the same?
ok imma just rewrite everytghing i have
$x = \frac{-k\pm\sqrt{-k^2+8}}{2}, y = \frac{k\pm\sqrt{-k^2+8}}{2} \
\therefore, \
P(\frac{-k + \sqrt{-k^2+8}}{2}, \frac{k+\sqrt{-k^2+8}}{2}), \ Q(\frac{-k - \sqrt{-k^2+8}}{2}, \frac{k - \sqrt{-k^2+8}}{2}) \$
The midpoint $M$ of $PQ$ is
$M(\frac{x1 + x2}{2}, \frac{y1 + y2}{2})$
ISAVAGE
is that right?
like on the first line?
arent they just solutions to the line when substituted?
ok for the P and Q is it the same?
tho
cuz yours rewords the numbers
if thats the case imma divide by 2 again to find the midpoint hopefuly it works
yeah ignore everything I said earlier
I read the output incorrectly
it's (-k/2, k/2)
hey i just wanted to say thanks for the help
tho
🙏
sorry for being really dumb
yea aha
anything else?
what's the follow up question?
when the value of k changes in the range found in Question (1) i.e. $-2\sqrt{2}<k<k2\sqrt{2}$, find the locus of Midpoint M like bro i thought we just did that
ISAVAGE
like did we not just do that
ok
- Given that circle $x^2 + y^2 = 4$ and line $y = x + k$ intersect at two different points $P$ and $Q$, solve the following questions. \
(1) Find the range of the values of constant $k$. alr did, i.e., $-2\sqrt{2}<k<2\sqrt{2}$
(2) Express the midpoint $M(x,y)$ of line segment $PQ$ in terms of $k$. we just did this one $M(-k/2,k/2)$
(3) When the value of $k$ changes in the range found in question (1), find the locus of midpoint $M$.
OMG
ok
I think it means to find a geometric figure that all M lie on
ISAVAGE
ok nvm
ex. a circle centered at the origin w/ radius 1
obv this isn't the answer to this question
like i know locus is like a line, circle, parabola etc
figures meaning the locus?
yeah
well
maybe when the line is perpendicular?
cuz when i move the line down M is like diagonal
nah lol
ok
I was about to switch languages cause the (1), (2), (3) is smthn I've only seen in Japan to represent subparts
what did you mean here then
like when u change the value of k
perpedicular to what?
the line is in fact perpendicular
but idt you rlly need that to figure out the locus
there's a much simpler way
yeah this a good strat
ok i would use k = 2, -2
lemme see
i wait im using desmos
so it would obv be (1,-1), (-1, 1)
then i would do
$y - 1 = \frac{-1 - 1 (x - (-1))}{1 - (-1)}$
ISAVAGE
ISAVAGE
yeah
dam
an easy way to recognise this is that the y coord is the negative of the x coord
tho to be safe, you might want to restrict the domain
cause there are certainly k where there's no intersections b/w the two graphs
like u mean $-2\sqrt{2} < k < 2\sqrt{2}$
ISAVAGE
good catch
uh
Recall the midpoint is (-k/2, k/2)
hm
The x value is -k/2, so the range is ||-sqrt 2 < x < sqrt 2||
ok so i figured tjat u divided by 2
cuz then it would make the x value -k/2
alr thank you
for the help
🙏
math is a struggle fr
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Use identites to simplify the following expressions
-tan(-x)cot(-x)
Any ideas on how to simplify this expression?
I had tried but I honestly don't know if it's 1 or -1
show what you've done
This is what I have done.
But I think I maybe have made a mistake
Not sure about the identities
Well isn't the identity is that.
if theta is negative. then tan is positive and vice versa?
same thing with cot
If cot(-x) OR -cot(x)
yk?
what do you mean?
tan is an odd function
so tan(-x) = -tanx
same with cotx
That's what I kinda meant.
so your boxed identities are true
see here
Hold on
I honestly have zero clue on this matter
The identites are a bit confusing.
I do know that both are odd functions
But your telling me that it should be -tan*cot
anyone please help me with this question-Consider that a, b, c, d are positive real numbers satisfying (a + c)(b + d) = ac + bd.
Find the smallest possible value of S=a/b+b/c+c/d+d/a
in your work, you have three negatives
Go to the "Math help (available) section to open your own ticket my friend
Here?
yes
Okay..
so this would mean that the answer is -1?
yes
Okay so the work is correct. just the final answer
yeah you made a simple sign error
And a negative
Yeah
Alright thank you
I shall open another ticket incase I have another inquiries.
@rustic goblet 🫶
@cinder oxide Has your question been resolved?
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In order to compute the area of a particular circle, Juan first measures the length of its diameter. The actual diameter is 20 cm, but Juan's measurement has an error of up to $20%$. What is the largest possible percent error, in percent, in Juan's computed area of the circle?
!satoro !
yes
so do we just take one of them into account?
yeah
so the actual area is pi10^2
Result:
1.44
so the correct one should be 100pi, the other one should be 144pi right?
ohh I see
1.44
so 44% ?
is that how you do it?
oh I see, got the question correct
thanks guys
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Anyone mind quickly double checking this?
For a number X to be in A the following rules must be met: If the prime number p divides n, then 2p+1 also divides n.
Find the smallest member of A
I got 10 but im scared its somehow wrong it feels to easy
10 definitely seems to work since 2 is prime and divides 10, and 2*2+1=5 also divides 10. The initial statement says "number X" and then uses n instead which is weird to me, but what you got seems valid. And numbers less than 10 don't seem to work
sorry x and n is a mistake on my part im used to n for intergers
Oh wait, the trick might be that 5 is also prime, but 11 doesn't divide 10
hmm so for all primes that divide it then 2p+1 must divide it. I interpreted it as if theres only one p because of the word “the”
Hmm, I've found that $$2\cdot5\cdot11\cdot23\cdot47\cdot19\cdot\left(3\cdot13\right)\cdot\left(7\cdot9\right)$$ seems to satisfy the constraints, but it might not be the smallest
Jelle
Maybe you can argue that 2 has to be a prime divisor and work from there actually
Yeah, I think that works
2 actually doesnt have to be i think since if you start with a prime the next number 2p+1 will always be odd. And to find the LCD you would have multiply two odd numbers together which is always odd
Lol, I messed up parity my bad
dw i interpreted the problem completely wrongly so just a partity mistake is fine lmao
can we say that n is always equal to the product of the primes that divide it and the 2p+1’s
Yeah, but some of the p's might be 2p + 1's as well
7 for example
(if 2 is in the factorization at least)
so you get these chains
yeah excluding the overlap then
I'm kinda afraid that it's impossible to prove that a certain prime is the factorization of n though
Hmm there seems to be something with sophie germain primes maybe
Theyre primes p such that 2p+1 is also prime
What kind of class is this probem from btw?
okay, I should know enough theory then
(I'm in last year of high school, but I have done olympiad stuff, so I'm familiar with nt)
Is this fermat's last theorem?
its to do with it but its a stand alone theorem
I've tried a couple things and it seems like starting with any prime below 30 will give a sequence like the one I sent, but without 2
just conjecturing maybe the solution could be the first non sophie germain prime since that would only need to divide itself?