#help-28
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I forgot that it was part of the overall thing
but we are gonna use that of course 
We’re gonna use this one 
oh okok
What we’re gonna do is to take more and more of the triangles, with smaller and smaller thetas, until the polygon turns into the circle for us 
The “taking (…) smaller thetas” is the theta -> 0 part
And we of course worked out the area of the polygon in terms of r and theta already, didn’t we 
Yep, all of that, we basically are doing $\lim_{\theta \to 0} \text{that}$
@devout valley
(I’m not writing out that expression because I’m on mobile and laying in bed
)
im doing the math on my bed, and ong im feeling the eepy but i gotta lock in
so we doing that limit expression
Awwww, let’s keep pushing so that we can both rest as soon as we can 
mhmhm
That’s the last part
writing the expression is our part 8, so we wanna have that written down
Then for part 9, we actually work it out 
ah so just for clarification the lim theta approaching 0 = this expression ^
I’m gonna do a bit of simplification for us, we wanna find $\lim_{\theta \to 0} \frac{\pi r^2 \sin(\theta)}{\theta}$
@devout valley
ohhhh
Yep, turns out I lied to myself and I would write it, look how friendly I am 
Awwww 
Anyways, do you know how to work out that limit?
(Assumedly they’ve taught you it
)
Well, they say they have, so if they haven’t 
uhhh the lim theta approaching 0 sin theta/0 =1 ?
We wanna use that, yep 
(The denom being theta of course
)
You’re also happy that constants just “scale” the limits, right?
(That you can basically find the limit, then multiply it by the constants)
multiply it by the constant 2?
Well, not quite 2 here-
For a start, I cancelled out the 2 and 1/2 to make our lives easier-
So we only have to consider this 
But $\pi r^2$ is a constant here, so we can equally work out $\pi r^2 {\color{green} \lim_{\theta \to 0} \frac{\sin(\theta)}\theta}$
For which, you told me you know how to do 
So, what’s the area of a circle? 
pi r^2
@devout valley
Sounds very familiar to me 
As it should be, as the green is 1 
And that’s part 9 done for us!
OMG
and then also answers part 10 i think
because we get the formula for the area of the circle
OMG
Yep 
I told you we would 
lemme write all this down real quick, just in case i have any questions before we depart
Yep sure
get it all down so we can rest easy 
okok i believe I got it all, thank you so much can I buy you a coffee or somehting
Awwww, happy you got it all down
and you’re very sweet, don’t worry about getting me anything, working with you has been pleasure enough 
AH MY HEART that so sweet, well have a good nights rest chart, it was a pleasure working with you <3
Awwww, I hope you have a wonderful night too! I’m gonna get myself some sleep 
hopefully see you around ❤️❤️❤️❤️
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find f(4x) using f(x) = 16-x^2
what
whereever you see an x, put 4x instead
using parentheses will be helpful
i recommend going through this free khan academy lesson 1 unit 8 https://en.khanacademy.org/math/algebra/x2f8bb11595b61c86:functions/x2f8bb11595b61c86:evaluating-functions/v/what-is-a-function
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I need help with this question.
I derived the formula to solve this question.
Here is my work
I Want to ask if this formula is correct to solve the question. If not which formula I have to use
@full vector Has your question been resolved?
@full vector Has your question been resolved?
Anyone. I just want to know if the formula is correct or not
It's correct
@full vector Has your question been resolved?
Ok thanks
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lol its alr bro go ahead
ty
why am i not getting the right answer here?
I took moments about c btw
ping me
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Im also so lost on this question
this is about all i've done
idk what to do after
do you know how to resolve a vector
the tension isnt vertically upwards, it's in the string
in this direction
ah
not sure what that means exactly
youre given the angle for a way to DETERMINE the vertical component of this vector
where we can express Fy for example as
sin theta = Fy/F
so Fy = Fsintheta
oh yh
but u dont have hypotenuse?
it's given in the question
oh is the tension
"the tension in the cable is 80N"
yep
do you think you can do it now?
ahh i rly dont understand what they're asking
isnt the centre of mass from the wall
just going to be half of 4?
i mean thats my understanding
the question specifies it's non uniform
ohhh
recall the definiton of centre of mass
ok
where all the forces APPEAR to be acting
it doesnt necessarily have to be in the middle
the question gave you an equilibrium case to determine it with moments
wait ik i labelled it wrong
but would there still be these reaction forces
and u take moments with that?
does this help
which was?
well i put x = 32 cause i used 40 instead of 40sin30
40sin30 is just 20 tho
😭
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,w 40 * 4=100 * x
just to make sure IM not tripping
ahhh
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yeah no no ur right
im trupping
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hi
i heard or read somewhere that non-real roots come in conjugate pairs
is the complex number -1 -i
considered non-real
yes
and if that complex number shows up as my root
then i would expect the other root to be
-1 + i?
yes
okay then im confused because i just worked through a problem and looked at the solutions
and the other root turned out to be 1 + i
can you show the solution
yes
/problem too
original problem, in swedish unfortunately
it says "solve the equation z = 2i, the answer shall be given in the form z = a + bi where a and b are real numbers."
and then the proposed solution
and i got the same answer, but i thought that the rule was they come in conjugate pairs
my bad , the conjugate complex roots applies to quadratic equation with real coefficients
like ax^2 + bx + c =0
a,b,c should be real
yup
sry that isn't my solution
ohh
did you try by eulers or x+iy
i think x+iy is easier for this question atleast
i did (z^2)^(1/2) = (|z|^2)^(1/2)(cos((theta + 2pik)/2) + (sin((theta + 2pik)/2)i)
and checked k = 1 and k = 2
but i could have checked k = 0 instead of 2
anyway thanks again
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Part (c)
Sorry if im opening a lot of help channels back to back i just did a mock exam and im self correcting all the ones I didnt understand 😅
So we need to turn that parametric form into a parabola
My only idea is to do
y(t) = a(x(t))^2 + b(x(t)) + c
But that wouldnt get us very much I think...
Alright, let's look at the equations we have 
We have that both
[
x(t) = {\color{pink} \cos(t) } + 1
]
and
[
y(t) = 4{\color{pink} \cos(t)} - 2{\color{orange} \sin^2(t)}
]

Ooo colours
Any more ideas now? 
Funny enough, I don't really like the colour pink 
Its my favourite 😝
(and yet my favourite colour is purple
)
Also W colour, doesnt get enough love
I think guys look really good in purple, not enough of them wear it
But OK, maths 😂
Well then, in that case, what's your least favourite colour you can think of? 
Orange
Cool, one moment please 
@devout valley
color 
oh
American spelling hehe
Grrrr 
britihs
Percy
Anyways, look at that nasty orange 
I get that we can convert the sin to cos
But I dont really know what were working towards
Just do it for now 
y(t) = 4cos(t) - 2sin^2(t)
y(t) = 4cos(t) - 2(1 - cos^2(t))
y(t) = 4cos(t) - 2 + 2cos^2(t)
OH
Its already a quadratic
I think I can solve
2cos^2(t) + 4cos(t) - 2
(It is, but not the one we want yet!)
No?
Cool, so now, what we have is
[
{\color{pink} x(t)} = {\color{orange} \cos(t) } + 1
]
and
[
{\color{green} y(t)} = 2 {\color{orange} \cos^2(t)} + 4{\color{orange} \cos(t)} - 1
]
and we want ${\color{green} y(t)}$ in terms of ${\color{pink} x(t)}$
Do you notice anything yet? 
What do you mean by y(t) in terms of x(t) sry?
You want to write y = [something that only has x in it]
Also one second 
@devout valley
Hehe 
Ok I thiiink I see what I have to do
x(t) = cos(t) + 1
x(t) - 1 = cos(t)
y(t) = 2cos^2(t) + 4cos(t) - 1
y(t) = 2(x(t) - 1 )^2 + 4(x(t) - 1 ) - 1
And I think I can just solve the rest myself haha
x(t) can just become x, right?
In this case
Yep, you can just write x there 
Awesome!!
I get it all now
Thank you again! (again 😝 )
WRONG EMOJI 😭
Accidentally really freaky
I didn't even catch it 
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How do I do this?
I have no idea what to do, I missed the day when this lesson was taught
I think you should have a formula for area
could you do it if the angle was 180 degrees
Nope I have no clue how to find these sort of areas
The unit just started and I wasn’t really paying attention in class
Percy is it theta/360 * r^2?
sigh
what about an entire circle
Yeah it’s like pi r squared
not "like"
it's exactly that
pi * r^2
now
if you wanted a 180° sector
that would be what fraction of an entire circle?
Half?
yes
so then how could you find its area
you didn't prime her with the "entire circle" question
fair
1/2pi(r^2) right
anyway
yes
but the idea is that a sector should be thought of as a fraction of the circle
please at least seperate the 1/2 and the rest
so now 130°
1/2 pi r^2 yes
this 130° sector is what fraction of its circle?
130/360?
how are you very much active on discord..what do you do for a living @onyx glen ?
honestly none of your business mate
oops
also you are obstructing
there we go!
@gloomy briar yeah so the area of the sector is that fraction times the full circle.
130/360 pi 18 squared?
the same logic you just went through with a half circle goes equally well for any other fantom
130/360 * pi * 18^2
Percy
Tysm guys I get it now!!!
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hi
i cant tell where i went wrong
i wanted that positive sign to be negative at the end
then it would be perfect
if that + was a -
when i take out the last term out of the p+1 sum
should it be negative?
i dont think it should be it doesnt make sense why it would
this looks right
this looks wrong
and so i assume the error is inbetween
but idk
it looks right too
i dont see what went wrong
<@&286206848099549185> This is an induction proof gone wrong, and I can't find where I went wrong.
i was trying to be cute by doing the base case last, but i just checked and the base case is true
so that's not the reason
there is a proposed solution
for this problem
this is what they do
that's crazy
well ok at least i was wrong about being wrong, i just didnt know how to continue, paradox
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Greetings! I am stuck on how to u-substitute ^^'
The whole problem: Find the area of the polar coordinates
r = e^-(theta/4), from pi/2 <= theta <= pi
So, I have gotten to this point:
A = (1/2) integral (from pi/2 to pi) [ e^-(theta/4) ] * 2 d * theta
The -(theta/4) * 2 becomes -(theta / 2), but now I need to u-sub this. I feel really lost on how to approach this.
you have (A=\frac{1}{2}\int_{\frac{\pi}{2}}^{\pi}e^{-2\frac{\theta}{4}}d\theta)?
PajamaMamaLlama
yeah ur right then
Where do I go from here? How do I U-sub this part? o>o
well really ur only problem is that -theta/2 is the exponent, yes?
Yeap
sooo what's the logical thing to substitute here?
yes so we say u=-theta/2
so we int e^u*dtheta
but of course that dtheta make no sense when our integral is in u, right?
so if we have u=-theta/2
We need to derive -theta/2
so what's the derivative of -theta/2 w.r.t to theta?
what's the derivative of (-\frac{x}{2})?
PajamaMamaLlama
I have no clue what to do with the / 2 part, but x^1-1 will become 1
So far, I have -1/2
and that is the derivative
Just that?
Nothing special to do with the denominator?
I am especially scarred and tired of forgetting so many special rules ;u;
nope, because it's just a constant and recall that (\frac{d}{dx}[cf(x)]=c\frac{d}{dx}[f(x)])
PajamaMamaLlama
we actually have -1/2 [x]' :)
alright so then derivative of -theta/2 is just -1/2, yes?
Looks about right. Nothing to drop down from the exponent
So now we have du = -1/2 d*theta
We need to shift -1/2 to the other side
Oop
though remember, we don't just shift, we have to multiply both sides by -2
Warning, what's the warning about?
to cancel that -2 guy in the denominator :)
but if this is what you meant then absolutely right
Was about to say that; just forgot to mention it.
So -2 * du = d * theta
-2 cancels the -1/2 on dtheta
now you're nearly there, there's one more thing you gotta do with definite integrals and u-sub, and do you know what that is?
That is to change the integral range (I dunno what its proper name is) by inserting the u-sub
your bounds, yes exactly!
So -pi/2 for the highest point, - (pi/2) / 2 for the lowest bounds.
Does the lowest bound just change to -pi/4? o>o
Ogie
Time to progress
alrigiht now putting it all together
oh wait
I realized something
you did make a mistake here
in the theta world the top bound is pi and bottom bound is pi/2
you had these as negative
Place in the pi and pi/2 there, and we get the negative bounds
I was just testing you 😅 /j
Alright I agree, that was my bad
[\frac{1}{2}\int_{\frac{\pi}{2}}^{\pi}e^{-2\frac{\theta}{4}}d\theta\to\frac{1}{2}\int_{-\frac{\pi}{4}}^{-\frac{\pi}{2}}-2e^udu]
I'm way better at catching smaller details when someone is working than I am working on the bigger picture.
PajamaMamaLlama
I am the complete opposite, so good thing 
which iss... 👀
Should come out as e^u ->-
Riiiiiiight...? ->-
Yay
So -1 * [e^u] bounds from -pi/2 to -pi/4
Nota bene: you were right to say we are indeed allowed to plug in the bounds right away only because just so happened to be (e^u), but not true in general :)
We cannot! But I was saving him for last.
But from here, what do I do...? o>o
Do we just have the formula of e - e?
Just ultra-generalizing for now
well pretty much nothing lol that guy is pretty much as simplified as it can get
you can technically simplify by factoring out a power of e but it will jsut cause confusion I see no reason why ur prof or teach wouldn't accept that answer
So we get -(e ^ -pi/2) + (e ^ -pi/4)
AAAAAAAAAAAAAAAAA
GODS I HATE THE MANY HIDDEN RULES OF MATH ;-;
Thank you Pajama!
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Hello, I have a question about notation
yes
and -> means we are outputting
depends how the C is drawn
yup complex number set
Thats a function from C to C
it means we are mapping
it undergoes something to yield something
that means i have an input x, and i get an output f(x)
"f is a function whose inputs are complex numbers and outputs are complex numbers"
that's the english translation
it says essentially nothing about what the mapping actually does to the input
defines or defined by
what are the inputs, what can be the outputs, that's it
it's a lot like a type signature in programming
im not really programming yet
unfortunately
im trying to use the : in "a mathematical sentence" that isn't too similar to the example i gave
to see if i understand
If S is a statement, and we can have a lot of different statements, can I say we have S:n statements?
oops
well set-builder notation is kinda like that
You'd have n statements, which you might label S_1,..., S_n
(where "_" is meant to mean "write what follows as a subscript")
Ratios
oh yeah
Simple numerical e. g. in Germany I have seen are more commonly written as what in UK/US schools would be more familiar as ratios
This is not "such that"
"f:C->C" is read "f is a function that maps the set of complex numbers onto the set of complex numbers"
Or, if I were to read/say this at speed, "f maps from C to C"
and sorry what does map mean
like isn't C already mapped to C
idk what mapped means <-<
"maps... onto..." = "takes inputs from... and whose outputs are in..."
A mapping is any such object that "maps", like above
A mapping is a function in the proper sense if, when you give it an input, it returns you at most 1 output
i thought that was like included in the definition of a function, not whatever mapping is
A function is a type of mapping
All functions are mapping; not all mappings are functions
Technically this should be taught when you learn about functions as an object, though since this never crops up again in HS (iirc) I can see why this might be confusing
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I'm a little confused here
I want to use uniqueness, but that only tells me that f is identical to tanx on 0 leq x leq 1. Isn't it possible for f to take on other values outside of this range?
Maybe I want to use f's analyticity but idk how that helps me
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posted elsewhere a while ago
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✅
is there any syllabus limitations?
like can I just start using archimedes principle here?
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Let ABCD be a trapezium (trapezoid), such that (AB) is parallel to (CD).
Let O be the intersection point of the lines (AD) and (BC).
Let O' be the intersection point of the diagonals (AC) and (BD).
Let I and J be the midpoints of the segments [AB] and [CD], respectively.
Show that the points O, I, J, and O' are aligned
I think i need to use homothety but im lost
@chrome ore Has your question been resolved?
<@&286206848099549185>
Did you draw it?
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For this question, would I put in my calculator cos^-1(.5045 or cos^-1(-.5045
oh yeah cos^-1(-0.5045)
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Hello world
I got 12 boxes with marbles inside, blue, purple and yellow, the amount is infinite but the base probability to draw a marble when grabbed at random is 94.3%, 5.1% and 0.6% respectively. The probability of blue marbles only decreases where purple increases and yellow dosent change. All blue marbles are the same, but there are 60 different purple marbles and 8 different yellow marbles. Purple marbles have 60 different animals printed onto the marble's surface where yellow marbles have 8 different tools printed on the surface. What animals or tools isnt important, but 3 animals out of the 60, 1 tool out of the 8 has a increased probability when drawing that type of marble. The probability to draw a purple or yellow marble dosent change but the probability for that certain type is increased. This will be called a rate up for simplicity. I have a 50% chance to get any rate up marbles and a 50% chance to get anything else, example the purple marble rate up is dog, lion and iguana, so i have a 50% chance to get either of those when drawing a purple ball and a 50% chance to draw some other animal out of the 57 non rate ups.
All 12 boxes:
- base probability for blue, purple and yellow, rate up
Purple = shark, elephant, killdeer
Yellow = screwdriver
2)probability of blue decreases, purple becomes 56.1%, yellow stays at 0.6% rate up same as 1
3)probability of blue becomes 0, purple becomes 99.4%, yelloe does not change, rate up same as 1
4)probability same as 1 but all purple marbles are the rate up ones only
5)probability same as 2, all purple are rate ups
6)probability same as 3, all purple are rate ups
7)base probability, rate up
Purple = penguin, kingfisher, camel
Yellow = knife
-
same probability as 2, rate up same as 7
-
same probability as 3, rate up same as 7
10)same probability as 7, but all purple is rated up only
11)same probability as 8, but the purple is rated up only
12)same probability as 9, but purple is rated up only
Box 1-6 are boxes used for event A where box 7-12 are for event B
Event rules: usually drawing marbles are from the first boxes (1 for A and 7 for B) which has the base probability, after drawing for 8 consecutive times without getting a single purple marble, i will draw from the next box (2 for A and 8 for B), if no purple marble is still seen, i will draw the 10th time in the next box (3 for A and 9 for B) which only contains purple and yellow marbles. When drawing a non rate up purple marble, the same rules apply for the next few draws except box 4,5 and 6 are used for A and box 10,11 and 12 are used for B instead where all purple marbles in those cases are the rated up marbles.
Question: how many draws on average/minimum is required to get a single elephant (one of the 60 animals printed on the purple marbles) in both events?
Situation: i simulated it, event A took 24 trials whereas even B took 15603 trials, the difference is too large so i want to calculate the real rates
<@&286206848099549185>
@torn jolt Has your question been resolved?
@torn jolt Has your question been resolved?
@torn jolt Has your question been resolved?
false, I love them.
question is not clear to me.
Here's what I understood:
We first draw from boxes 1 and 7, if the first 8 are not purple we move on to the next box but I don't understand how many draws we do there. And nothing even after that
One more thing I don't understand is that you've not told about the total number of colors or the number of marbles of any color or the distribution of the marbles of any color. But I could deduce that there are 60 purple marbles in both events' boxes.
I stated that the number of marbles are infinate for simplicity
Its just probability with no amount
How many draws is what im trying to find out
There are 60 types of purple marbles but the number is not 60
do you do only 1 draw in the next 5 boxes in each event?
and after that the cycle continues to start from the first box again?
But i just keep drawing
Until i get purple elephant marble
How many draws on average/minimum is required?
isn't minimum 1, lol
are there 2 colors?
Oh true
So then the average then
but the last 4 boxes in each event doesn't contain blue, right?
The 10th box in eavh event dosent contain any blue
Its like
The first 8 times have the qame probability
But the 9th time has increased for purple
And the 10th has no blue
10th draw*
how is it increased in 9th?
I change the box
I got 12 different boxes
I draw in them at spesific cases
but that box still have all 3 colors
Yes
Only if i dont draw a purple in the 9th where i draw from the 10th there will be no more blue balls
I'm currently solving for one event but I just read that you want the probability of getting at least one in any event. I don't have a simple solution and due to large values(60, 6) I'm actually writing a code to solve the problem but if we consider both events then I think it would get more complicated.
Oh damn
This is for
Which event?
It's ok just one is enough
one event, aren't both events the same?
Oh the first event has the elephant in the rate up
The second dosent
Wait, the first assumption of my sol was that the probability of elephant is 1/60.
Oh then it's the 2nd event
So we want to calculate the expected #draws to get 60 purple marbles.
And that I did with code.
if you want I can share the code.
Ooo getting all 60 types works as well
Suree thanks
no, no, as the probability of getting elephant is 1/60. So the expected number of purple marbles such that we get an elephant is 60. And so I calculate the expected number of draws to get 60 purple marbles.
Ohhh
Yess it works as well
Thankss btw
np
#include <bits/stdc++.h>
using namespace std;
#define ld long double
void solve()
{
ld dp[6][60],p[6];
for (int i=0;i<6;i++)
if (i==2) p[i]=(ld)1/(ld)2;
else p[i]=(ld)1/(ld)3;
int lim[6];lim[0]=8;
for (int i=1;i<6;i++) lim[i]=1;
for (int i=0;i<60;i++)
{ // everything is cyclic, so first we need to fix one variable
ld cnt=1,pr=1,val=0;
for (int box=0;box<6;box++)
{
for (int draw=0;draw<lim[box];draw++)
{
if (i)
val+=pr*p[box]*(cnt+dp[box][i-1]);
else
val+=pr*p[box]*cnt;
cnt++,pr*=(1-p[box]);
}
}
// dp[0][i] = pr*(dp[0][i] + cnt)+val
// dp[0][i]*(1-pr) = pr*cnt+val
dp[0][i] = (pr*cnt+val)/(1-pr);
for (int box=5;box>0;box--)
{
// dp[box][i] = p[box]*1 + (1-p[box])*dp[next box][i]
dp[box][i]=(1-p[box])*dp[(box+1)%6][i]+1;
}
}
cout<<dp[0][59]<<endl;
}
signed main()
{
cout<<fixed<<setprecision(20);
solve();
return 0;
}
Here's the code, you may ask an AI to understand it and if you do, please share the response with me too.
Suree tqtq
What language tho
C++
I see
np, actually I took it as a challenge when that guy said "nobody likes probabilities".
XD HAHAHGA
Thank you anywayyy
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which inequality should I use?
kheer257
RMS-AM Inequality?
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rounding in mathematics.
how important is rounding?
assume there is 3 choices:
- No rounding
- Rounding to the nearest, where half will be rounded up.
- Rounding to the nearest, where half will be rounded to nearest even number (Banker's Round).
the normal rounding that I usually see mathematicians use is the number 2 rounding method. why didn't we use the Banker's rounding, especially since it's better?
Actually is rounding really that important?
fundamentally you have to round numbers to some decimal precision for any physical machinery to work
banker's rounding is better in general so i really dont know why they dont teach that instead
maybe because it is less intuitive relative to normal rounding
hmm...
In mathematics there basically is no rounding, you only care about precise values. In the physical sciences, you'll take the best approximation you can get. Rounding a half up or down is just a convention, and doesn't really matter in practice because a physical measurement will never be exactly half of a whole number, or exactly halfway between two known values.
i see... thx everyone
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what happened here? How did the sqrt(x) get on the bottom?
x = sqrt(x) * sqrt(x)
1/x isn't sqrt(x) tho? D:
do I multiply the top and bottom by the sqrtx?
$\frac 1x \cdot \sqrt{x} = \frac{\cancelto{1}{\sqrt{x}}}{\sqrt{x} \cancel{\sqrt{x}}} = \frac{1}{\sqrt{x}}$
ℝαμOmeganato5
x = sqrt(x) * sqrt(x)
oH
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Find the volume bounded by z=sqrt(4-x^2-y^2), z = sqrt(x^2+y^2), and z = x^2+y^2, in the first octant
the first integral is x^2+y^2 to sqrt(x^2+y^2), the second integral is sqrt(x^2+y^2) to x^2 + y^2, and the third integral is sqrt(x^2+y^2) to sqrt(4-x^2-y^2)
is this correct
@torn plinth Has your question been resolved?
can u put it in proper integral notation
@torn plinth Has your question been resolved?
you can see that the integration region is invariant under rotation
so you may wanna go polar
or cylindrical
a good choice of coord sys can make your life easier
are my limits for z correct?
first sketch a good graph (on paper or online, just the desmos 3d tool that i've shown you), which will answer your question
I basically graphed the zy trace, and got this:
blue curve is basically the cone z=sqrt(x^2+y^2), red curve is the paraboloid z= x^2+y^2, and the black curve is the sphere sqrt(4-x^2-y^2)
then imagine the 3D version, by rotating the figure around the z-axis
it reduces to a high school volume of solid of revolution problem
why are my bounds wrong tho? I can't use the 2D version to get the bounds for z?
cuz in many other problems it worked
if i assume that that specific curve is part of a larger surface
write things in a complete sentence
what actually is this?
integral for what?
ofc i know
just to say that it's meaningless to write the first two terms, which cancel each other
so by looking merely at the last term, you'll immediately see that it makes no sense
where are the "dx" and "dy" in your picture?
write things out clearly
ok i will write it one moment
in fact you see the rotational symmetry of the region of integration around the z-axis
that's why using cylindrical coordinates is a smarter choice
how come you have '9' inside the root sign?
how do you get those 1.3, 1.6, 2.1?
those look sus
i suggest that you have a clearer mental image, by colouring the desired solid's (vertical) cross section passing through the origin
you'll then see that your desired quantity should be a sum of two iterated integrals
instead of three
This is what I got. “R” is the 2D region for each case.
follow what i said in my prev msg 1st
after you've finished, if you have time to kill, retry the problem using volume of solid of revolution
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hello! i don't understand algebra at all
like what
like basiks
like bsics
what have you learned?
just stay calm and $(x+y)^2=x^2+y^2+2xy$
Percy
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Is my answer correct? Find the volume bounded by z=sqrt(4-x^2-y^2), z = sqrt(x^2+y^2), and z = x^2+y^2
@torn plinth Has your question been resolved?
@torn plinth Has your question been resolved?
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I think substitution is best here?
get like 1/u and then ln(u) is that possible?
yes
e is just a constant so yes
ah yeah true
We're not allowed to use calculators during this exam so how would you go about solving the definite part of the integral yk the e^2-e
riemann
,tex .log rules
riemann
thanks, can I ask another question without opening a new channel?
cuz if so I have no idea how I would derive this one
riemann
yeah but I dont quite understand how I would do e^(e^ex)
write f as a composition of multiple functions
so like e^g(x) where g(x) = e^ex?
that works
okay thanks!
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Are these right?
,rotate
what’s this for
calc 1
im mainly wondering about b (2nd one) and c because its dne if the left and the right dont match up, but if theres a solid point doesnt that mean that its the answer?
you're pretty much set :D, except for the last two items
do you want help breaking it down
you love breaking stuff
yep, since two sides of a limit must converge at a single point for a limit to exist
alright
same for the last item
so that one would be 3 then
yep! limits are independent of the function's actual value at x=a
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Were are supposed to use inverse trig functions
I know the trig formula im supposed to use but am confused how to change the function inside the sqrt to match that formula
Which formula
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i need help with this
So i got
sinx^1/2=cosx
then in sin^2x + cos^x=1 i subed in
got
sinx^2 + sinx^1/3=1
then i let sinx by y
got
y^2+y1/3=1
then i did
y^6+y^2=1
let y be a
so now i have
a^3+a=1
but i dont know what do next?
@bright thicket Has your question been resolved?
Should be 2/3 exponent here
Because the power of cosine here should be 2
@bright thicket Has your question been resolved?
(sinx)^(1 / 3) = (cosx)
let y = sin(x) or smth, you get y^2 = (1 - y^2)^3, which you solve as a cubic
the answer is not pretty since you have to solve an irreducible cubic
$\sin(x) = \sqrt{1 - \sqrt[3]{\frac{2}{3\sqrt{93} - 27}} + \sqrt[3]{\frac{\sqrt{93} - 9}{18}}}$
Mqnic_
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I am getting wrong answers...please help
,w solve (2y-3)^2 + y^2 = 233
@void tusk I agree with your work. So does WA
Why do you think the answers are wrong?
there's 2 sets of results no?
The second pair need you to use the y=-28/5 value
i didn't solve the x and y
y=-28/5 gives you x as -71/5 which is the second answer
For each solution
how 28/5
yes right...
but i am getting both wrong
there are two possible solutions to this, which means (x1,y1) and (x2,y2)
what you got is y1 and y2
you need to get corresponding x1 and x2
then the given answer would match the pairs of (x,y)
putting value in first step??
id reccomend for future problems you write the equations in terms of two variables
x^2 + y^2 = 233
and then choose one of them, either x or y, does not matter if not specified to make the second eq
here you basically did x = 2y - 3
and then you substituted
but you did all this directly
by showing these steps it'll be more clear
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Pls help
,rccw
well clearly a cannot be 3 or greater, yes?
Ummm yes
Mhm
then you get 2002 + 101b + 11c + 2d = 2019
Mhm
so 101b + 11c + 2d = 17
subtract 2002 from both sides lol
But their values can’t be decimal
whose
b c d
and at what point did i say anything about decimals
Ok ok
do you understand what i did
Yes
ok do you see how to continue
Nope
what can b be
can b be 9?
Yes
how so?
Wait wait how can this be true if they are not decimal or negative
if b is 9 the left hand side is too big
hell even when b is 1 the left hand side would be too big
Ye
so what's the only thing that b can be
0
Do think we should make a 1
Wait 9+9+9+9 is 36. So 2019-N is less than or equal to 36. Which is less than or equal to 1983
that will come later
we still aren't done with the a=2 case
yes b=0. so now 11c+2d=17.
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can someone help me qués 22
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"using the table above, list all possible unique results from adding Dice 1 and Dice 2?" what does it mean by 'unique results'
whats is the problem
question 5.
list the number u can get when u add two dices
so it woupd be 2,3,4,5,6,7,8,9,10,11,12
u cant get 1 in that list because there is no number add up to 1 in dice 1 and 2 the minimum u can get is 2 because 1+1 is two and maximum is 12 6+6
yeah
i never learnt that in yr7 jeez what is my sisters class learning
thanks though
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Could someone help me with this question? The one on the bottom
,rccw
First of all I suggest you redraw it to get a better understanding
Because the obvious step is not obvious when you draw it like that
Oh
Draw it like a proper right angled triangle
What is the area of a triangle