#help-0
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pour some into my brain
oh
alr ig
also one more help
can you tell me how to apply component and dividendo
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when I do the integral from -999 to 999, I get 0. Why does the integral not converge when it goes from -infinity to +infinity? How can I show that it does not converge
when you have an integral with two improper bounds like that, you have to split it somewhere in the middle
for example, if we choose to split it in the middle, we can write:
,,\int_{-\infty}^\infty x^3 \odif{x} = \int_{-\infty}^0 x^3 \odif{x} + \int_0^\infty x^3 \odif{x}
pnoןɔ
then we need both improper integrals to converge individually in order for the overall improper integral to converge
@dusky igloo Has your question been resolved?
Thanks
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Any idea in regards to 22b?
I was thinking two senarios, assuming the two are A and B
- A is in one of the team, so 5/9
- A is umpire, so 8/9
But I just can't think further, it is given 22a=310
i think it is easier to find the probability they are on the same team and then subtract that from 1
Yeah I was thinking about that also
So in this senario that would be 310(4/9) right?
Or 9C4?
Here is when I became a bit loss on the answer of 210
wait how did they end up getting 310 for 22a
that equates to 315
and how does dividing avoid repitition here
see i went 9C4*5C4, as we have 9 we can choose 4 of them to be on a team, then choose 4 more out of the remaining 5 ot be on a team and the last guy will be the ref
but that gets 630
My fault, I misremembered the answer. But it should be 315 according to the textbook
That was what I and the person I asked got to and made the most sense
is the final answer 210?
oh didnt mean to reply to myself
Yes
aight
so we want to find all the ways that they are on the same team and subtract it from the total possible ways of arranging the team
Yup
if we make those 2 people on 1 team already that means we have 7 people left out of those 7 people 4 people are going to be on the other team so 7C4, out of remaining 3 players 2 of those players are going to be on the same team as the other 2 so 3C2, last guy is the umpire therefore there are 7C4*3C2 ways they are on the same team
therefore if we subtract 7C4*3C2 from 315 we should get all the ways they aren't on the same team
7C4*3C2 = 105, hence 315-105 = 210 ways they arent on the same team
aLL G
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I claim help 0!
Can someone explain this simplification step here? I don't really get how the difference of two cubes is applied here
Nevermind I understand it
@queen quiver Has your question been resolved?
I am in Calculus 1
Would I need to know how to demonstrate why lim x->0 for sin(2x)/x = 1 via Squeeze Theorem as well
I guess it'd be enough to know how via L'Hopital's
Why is it c=2
Nvm
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Can someone help me understand why if x belongs to rational cos(int pi) beomces +-1.Why cant it be zero?
Cant x times n! be a fraction?
x*n! cant be a fraction when n->infinity
Thats where i dont get it
if x is rational then x = p/q, then q!*x would be an integer, you agree?
yes
then any n greater than q, n!*x would be an integer
np
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Does anyone have a video / guide
On how to find the domain and range of a function
Just search on youtube
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how do i work out sd again???
Δyssrupt
@slim chasm Has your question been resolved?
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If a function has no turning points, can i say that if f(5) is smaller than f(10) the function is increasing?
just an example
Yes, well depends on what you mean by 'increasing'
"increasing function"
But if a function is strictly increasing then if a < b, f(a) < f(b) for all a, b
Increasing can be like $a \le b, f(a) \le f(b)$
south
So both work if a is not equal to b
You also would likely need continuity
Yeah ofc
Ah this is a rational function so f'(x) = 0 is impossible
Ye
The idea is that if f'(x) > 0 for all x then it's increasing
If f'(x) < 0 for all x it's decreasing
How do i prove that?
And otherwise it's neither
This could happen if there are turning points right?
Yes
But i proved there are neither
You must have $\lim_{x \to a} \frac{f(x) - f(a)}{x - a} > 0$
south
So $\lim_{x \to a} f(x) - f(a) > 0$
Cool so that's it
south
Mind running through what should i write here?
Thanks
Find f'(x), set it = 0, prove no turning points
And then prove increasing/decreasing, but what is "a" here
Don't worry about that
a is just an arbitrary x value
We need it for the definition of the derivative
Yes so if there are turning points that are not saddle points, it cannot be an increasing or decreasing function
You need to find the second derivative or sketch a sign diagram
question didnt explicitly say find 2nd derivative though
I think they're taking increasing to mean that the function can be flat
Yeah that's the normal definition
Like with this definition y = x^3 is increasing
But it has a critical point at x = 0
The critical point is just a saddle point and not a turning point
Point of inflection?
You can prove this by seeing that the slope of x^3 at, say, x = -5 and x = 5 are both positive, hinting no change of slope right?
Yeah
thanks
but increasing vs decreasing is my proof okay or not
like showing that for a>b f(a) > f(b)
As long as you get the idea that f(x) having turning points almost always means that it is neither increasing not decreasing, you're good
Ah i see
Thanks
I understand it now
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hello i have a plane
x = 1 + s - t
y = 2 + s + t
z = 3 - s + 2t
and i want to rewrite it to this form
ax + by + cz + d = 0, how do it (also what is this form called, math english is not my main)
So the plane has (x, y, z) = (1, 2, 3) on it if you set s = t = 0
Now the direction vectors come from (s, s, -s) and (-t, t, 2t)
And we want to take the cross product of those two vectors
But it would be easier to take a scalar multiple out from them
So we can just do (1, 1, -1) cross (-1, 1, 2)
,w (1, 1, -1) cross (-1, 1, 2)
This is your normal vector
So a = 3, b = -1, c = 2
Substitute in the point (x, y, z) to find d
hmm thanks i am going to try this is new and confusing for me
No worries
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Could someone explain me this?
116=244+200-441,81 cos
how did the -382 come out? i got -328
and what after that?
@chilly hedge Has your question been resolved?
<@&286206848099549185>
-328 is correct yeah
so did the teacher miswrite it?
only case yeah
and how do i get 42,06°?
its cos right?
yea
$$\cos\left(\alpha\right)=\frac{b}{c}$$
$$\alpha=\cos^{-1}\left(\frac{b}{c}\right)$$
Project_Nova
if i remember correctly it should be this 😭
so how tf do i put this into my calculator? 😭
let me pull out mine holdon
actually nah wait
yea i got that, how do i put that into? what do i write?
one sec
shift cos
yea?
that is how you get it on the calculator
no i swear im starting to tweak out
so im here at -328= -441,81 cos
What do i do from here?
a2=b2+c2 -2bc cos alpha
116=244+200-441,81cos alpha
i got -441,81 from an other thing
but thats 100% correct
$$-328=-441.81\cos\left(\alpha\right)$$
$$\cos\left(\alpha\right)=\frac{328}{441.81}$$
$$\alpha=\cos^{-1}\left(\frac{328}{441.81}\right)$$
Project_Nova
i think you have to press another button
this last thing worked
i dont even know the name im failing math
yep
i think its inverse trig 
but then how tf did the teacher get 42,06
is he acoustic?
no
because he wrote -382 instead of -328
lil mistake i believe :P
but when using shift cos is it okay to leave the - behind?
leave what - behind
that 30,17
on the example above its 328, and mine is -328
i can leave that - behind?
because both side are negative
we can multiply it with a minus one
both side
and - disapears :D
or when you uh divide
if top and bottom are negative it cancels eachother out

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im supposed to use a definition and not the wronskian, which states a pair of functions are linearly independent on an interval if neither of them are a constant multiple of each other
on that interval
how do i show that this one is linearly independent/dependent?
on the interval (0,1)
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hi! i just need some clarification on why $sin^2t$ needs to be derived with the chain rule and not the power rule? I know how to do both methods I'm just not sure why the chain rule is the one applied to this problem
kne
oh lol i didn't think it would do that to the whole paragraph
if you did just the power rule, you would get 2sin(t), right?
yes
but the problem is that you're taking the derivative with respect to t, not with respect to sin(t)
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Does x + x^2dx = 1 + 2x or x + 2x?
Does the dx apply to the entire expression or just the x^2 because no parenthesis
@swift saddle Has your question been resolved?
This is why I don’t like help channels
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HHIII
Helloooooooo im hereee im backkkk
exam tmr im running so late with time
i was hoping to get some help on my review
?
ahh
what help do you need?
do you know how to add matrices?
do you know what matrices are?
sortaaa
then, what are they?
theyre what number one is
i dont rly need to learn this i need to just know how to solve it for my exam tmr
its a bullshit class
just need to get a good grade on exam so i can finish this semester
well, look at the first question
looking
and at the answers, what do you think fits the best
do i do -7 plus 6
if the sign between the matrices is addition
and 1 + 2
a[row][column]
is the index
so when i refer to a11 its the top left elemnt
which is -7
and in the second matrix its 4
so when you do addition on matrices, they need to be of equal rowsXcolumns
if they are not, you cannot do addition
so in this case the matrices are both 2x2, meaning you can do addition
you understand this far?
indeed
so what about # 2
@cyan pecan Has your question been resolved?
YESSS
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I still dont get fundamental principle of counting 😭
For the first show, how many choices does she have?
this one I still get it
3, but I dont really get the questions I suck at word problems 😭
Thrice means three times
ik but I dont get why it's based on first stop second stop and third stop
you only have 2 options left after the first stop
Ah, yeah that‘s quite common. Trick is to read them thoroughly two or three times, and write down what you know about the problem, and what the problem wants you to find
is it bec it says there "ways to arrange her tour schedule"?
yes
Yes, and usually you don‘t repeat a city twice in a tour
ohh then I get it how about this one, wait give me a sec
A model selecting her outfits purchased 6 blouses, 4 skirts, and 3 blazers. How many different new outfits consisting of a blouse, a skirt, and a blazer can she create from her new collection?
I got confused on the different new outfits part
Well one outfit is blouse and skirt and blazer
And little trick, in maths, when you hear "and", think multiplication, and when you hear "or", think addition
ohhh
thanks so how do I solve this?
Well, we know that one outfit is blouse and skirt and blazer, how many choices does she have for each?
6 for blouse 4 for skirts and 3 for blazers
is it.. 3x3x3?
Haha since it needs to consist all 3 of them and there r only 3 blazers...
Well, theoretically she can have the same blazer but with different blouses, so it wouldn‘t be 3x3x3
If you‘d like you can use smaller numbers and like draw the thing. Say you have 1 triangle, 2 circles and 2 squares, how many groups of 3 different shapes can you make. You might notice a pattern
"Easy" is relative. It‘s easy for some and harder for others
yeah ur right, I was absent when they taught this
Wait my example might not even work the same way, ignore this
Things like these are not really fresh in my memory. My mind tells me 4, but I couldn‘t explain it intuitively. I asked in the helper channel so someone else might come here and explain better :)
Thank you though 😄
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how does htis prove anything???
I thoguht this was a reciprocal function
oh wait is ti because it's a reciprocal function the deonminator must always be positive or 0?
approaching 0**
since the slope of the graph is always positive (strictly/monotonically increasing), tangents to the graph cant be negative because that would imply the graph has a negative slope at some point
no
A lil confused on some stuff but I'll try them again
just ask here
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✅
how is F slowing down?
I thought it was speeding up
or is it slowing down comparatively to E-F
the speed is decreasing
speed is absolute value of velocity/slope
in other words it's getting flatter
but this is displacement over time graph I thought
S is denoted as displacement in my curriuclm but doing different questions is S supposed to denote speed?
it is a bit hard to see though lol
idk it depends
my institution uses x(t)
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✅
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I don't get
the last part on how they sovled for the derivitive
I understand chain rule is used here yes
but I don't get (-3/(2sqrtx)
that part
kk so what did you get after applying Chen Lu
I wasn't sure how to do the (-3/2sqrtx
part
Just that part
I understand how to solve the rest of the equation
ohh so differentiating -3/2 sqrt(x)
yeah
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Okay this is a random question I thought of. I don't know if such a problem can be answered or not as I do not have a high enough math education to answer such a problem but I thought I might as well ask in case anybody wanted to take a crack at it.
The problem is as follows:
You are playing a game with your friend. You setup bins with balls in them and your friend picks balls from those bins.
A bin can hold up to 5 balls.
You can drop up to 5 distinct types of balls in the bin and/or you can drop multiple of the same type of ball in the bin without restriction. The bin just cannot hold more than 5 balls.
In the game, if your friend picks a certain type of ball, they will either automatically lose, automatically win, or have to pick from another bin. This other can be a bin picked from previously or a bin that has not yet been picked from. When your friend picks from a previously accessed bin, they pick with replacement so it will still have the same makeup of balls from when they first picked from it.
There can be multiple types of balls that result in an automatic loss or an automatic win.
Given that you can place any number of bins before the game starts and can determine from what bin your friend starts picking from, is it possible to create a setup of bins for any given rational probability of your friend's victory?
If you need clarification for the problem, let me know.
As a side note lemme just say that this would be a REALLY boring game to play.
Do you allow infinite number of bin ?
Ah no my bad you said rational so it’s useless
You can have as many bins as you want
The probability of winning just has to be a rational number
E.g: If I wanted the probability of my friend winning to be 1/7 I could make the setup this:
-Bin 1: 50% chance of going to Bin 2, 50% chance of Losing
-Bin 2: 1/4 chance of Winning, 1/2 chance of Losing, 1/4 chance of going back to Bin 1
I think the fact that your friend can go back to any bin he want destroys your game
Because then it’s not determinist
Your friend does not choose to go back to any bin he wants
You decide when your friend goes back to a previous bin
Before the game starts ?
Yes
So why not juste placing the same bin after
You decide everything before the game starts. The game is 100% deterministic. Your friend isn't making any actual choices.
The problem isn't to just make it as hard as possible for your friend to win because you could just keep placing more and more bins. The problem is asking is it possible to make the probability of winning any rational number you wanted.
Like if I wanted to make my friend have a 832/1731 probability of winning could I make a setup such that that occurs? Can I do that for every rational probability?
This is impossible to make 1/2 chance to win
Because there is 5 ball
You don't have to place all 5 balls into one bin.
You can place up to 5 balls in a bin.
So you could choose to place 4, 3, 2, or 1
Yeah no it was just a random problem I thought of lol
I was just wondering if anybody had any idea how to approach something like this
-Bin 1: 50% chance of going to Bin 2, 50% chance of Losing
-Bin 2: 1/4 chance of Winning, 1/2 chance of Losing, 1/4 chance of going back to Bin 1
^This results in a 1/7 probability
In this case the friend begin in wich bin ?
Bin 1
Yes that probability converges to 1/7
Damn you’re committed
When your brain makes up a random problem that you're not able to solve as a means of procrastinating:
-Bin 1: 50% chance of going to Bin 2, 50% chance of Losing
-Bin 2: 1/4 chance of Winning, 1/2 chance of Losing, 1/4 chance of going back to Bin 1
1/8 chance of winning directly (that is to say getting the 50% chance of going to bin 2 and then the 1/4 chance of winning)
Given that you're sent back to Bin 1 (which is a 1/2 * 1/4 = 1/8 chance), there is another 1/8 chance of winning.
As you can see, this results in the probability of winning being an infinite geometric series of 1/8 + 1/64 + 1/512 +... = (1/8) / (1- 1/8) = 1/8 * 8/7 = 1/7
But this is just for a 1/7 probability. The question I have is: can this be done for any rational number probability?
Yep I calculated it too
So you generated 1/(x-1) when x=8
With 5 balls I don’t think we could genrate other interesting number with this pattern
I think I would go for the binary decomposition intuitionally 😂
I don’t know but I hardly see a way to make an algorithm that make the good configuration for any given rational number
Yeah I was trying to think and I just couldn't see a way to generalize any of this
Even just for all 1/x
(Wich would be incredible if it’s worked for that)
But that’s a fun game actually 😂
I mean
The game is to generate a given rational number
The game itself is incredibly boring lol
the concept of the game is interesting
Imagine playing this game just going through a bunch of bins your friend laid out and picking out a ball from each of them lol
That’s actually something I would love doing while procrastinating
I think I would laugh and then after 3h just 🔫🔫 in his head
lol
I sent the question to one of my friends and he came up with a way to create a 1/13 probability (discrepancy in printed result is due to trial size)
Bin 1: 50% chance of losing, 50% chance to go to Bin 2
Bin 2: 50% chance of losing, 25% chance of going back to Bin 1 or going to Bin 3
Bin 3: 50% chance of winning, 50% chance of going back to Bin 1
Because initially when I thought of this problem I thought "there's no way you could create a probability X/Y where Y is some prime number that wasn't 2, 3, or 5" simply because of the limitations of what probabilities of each of the 3 options you could make for each bin but 1/7 and 1/13 at the very least have solutions (or seem to anyways).
But the ability to loop back to previous bins yields some...interesting results.
@bleak harbor Has your question been resolved?
this would fall under markov chains, but it kind of reminds me of problems where you try to make probilities like 1/3 with coinflips
if you're able to feed things back into each other you probably get everything, it's sort of how continued fractions work
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Can someone remind me the rule on how to factor things like this
ok thx
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<@&286206848099549185>
Do you know what supplementary angles are
No I asked my teacher when we get to that and she said in a few weeks
It means they add up to 180 degrees
!15min
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is this a test?
stop being a snitch bruh
??
still need help w this?
who are you?
Yes
ok
first, supplementary agles are those that theyre added up to 180 degrees
like if you have an angle thats 70 degrees, the supplementary angle would be 110
cus adding them together would give 180
okey. vertical angles are the pairs of opposite angles formed when two lines intersect
okie i think
KLI AND NPM
That not an option there
then i think its MNP AND JKI
It was wring
@hearty compass Has your question been resolved?
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@hearty compass Has your question been resolved?
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did you try to draw it out?
first consider when will |a+b|=1
Yeah, notice that if you have vector a be (1, 0)
Then you will have an equilateral triangle if a + b lies on the unit circle
In fact, two equilateral triangles: one on top and one on the bottom
Yes
So theta is actually not the anticlockwise angle
It can be both anticlockwise and clockwise
So only $0 \le \theta \le \pi$ is possible
south
So what's the angle between the two vectors when |a + b| = 1
If both of them start from the origin
Ok can you show me then
So that doesn't satisfy |a + b| = 1
A circle with radius 1 centered at the origin
So it makes an equilateral triangle if you draw it out
so the magnitude of a and b is equal but not 1?
Nah, the question says that a and b are unit vectors
So they both have magnitude 1
Yeah so then if a and b start at the origin
That's not the correct angle though
120
No worries
(Imagine rotating b closer towards a: the black resultant vector will still be inside the circle)
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hii
i am doing an integral
but i get a weird answer
$\int_{-\pi/2}^{\pi/2}{e^{-\tan^2 x}\dd x} = e\pi \mathrm{erfc}(1)$
what is an 🍓
this is the correct answer
looks correct
but i get this but without the erfc(1) factor
with which method
i did a substitution where u = tanx
then dx = du/(1+u^2)
i used contour integration
from there on i used contour integration
can u send a pic or smth?
uh the way i wrote it down is kinda shitty but sure
yes
the integral over the arc doesnt go to 0 in this case
it does not?
theres some criteria the function needs to meet for it to go to 0
lemme check it again
im gonna do it all again but less shitty
jordans lemma
our complex function is $f(z) =\frac{e^{-z^2}}{1+z^2}$
Obotron
doesnt satisfy the form required for jordan's lemme
is this correct
e^(-R^2 e^(2iθ)) decays rapidly as R goes to infinity
1/(1+R^2 e^(2iθ)) too
faster than the remaining R
not necessarily
e^(2iθ) can be negative
in that case e^(r^2) blows up to infinity
right
im not very advanced in contour integration so i dont know how to get around this
when i solved this integral i used feynmann's trick
Help me if my answers correct
!occupied
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oh sorry
@crisp fulcrum Has your question been resolved?
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Do you know what the gradient is? Or at least how to calculate $\grad f(x, y, z)$?
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yeah yeah i just forgot how to differentiate lol
fixed it now
Alberto Z.
Oh ok nice
thanks anyway
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im not real sure what to do for this one
look up properties of a parallogram
and properties of a rhombus
so i know that a rombus needs to have four congruent sides and opposite sides that are parallel
but i dont know if they are congruent
but its given that all sides are parallel
what do you know about properties of a parallelogram
two diagonals bisect and sides are equal
which sides
all of them?
im lost
look up properties of a parallelogram
you mean equal?
yes
first based on the first two statements,
do you agree that you have a parallelogram?
yes i agree that the shape is a parallelogram
now applying the property concerning opposite sides,
what would AB be congruent to?
bc
DC
yes
now again pplying the property concerning opposite sides,
what would BC be congruent to
AD
yes
This means all four sides are congruent which is the definition of a rhombus.?
yes
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be careful with which option you select though

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.close
Youll need to square both sides twice
thanks il do that
my classmate said i needed to do difference of 2 squares and make a simultaneous equation which im not sure how id do
since theres only x no y or any other variables
Nah what
Don’t overthink it
Just square twice and make sure to consider domain throughout the problem
Difference of squares would be 9-x^2 for example, which can be factored
Whats domain? I havent learnt that yet in class
my teacher put this question up as a challenge
Let’s say you’re taking the square root of a
just check your solutions with original equation after ur done
do u mean like to get a square root that is an integer?
or just cant be square rooted
The latter
maybe irrational numbers like pi cant be square rooted?
They can be, it’ll just be an irrational number
oh ok then im not sure
-1 cannot be
whats the square rooot of -1
Double squaring is the only method I see ig
oh got it yeah i shoulve got that
So what numbers can be square rooted
positive numbers
And 0
So at every step of the problem, make sure that what you have under a square root is >=0
Or just solve it normally and then retrace your steps to make sure you never had a negative in there
And also one more thing, make sure you’re never setting a square root to a negative number
For example if sqrt(2-x) = x, you know x>=0 cause otherwise it couldn’t be equal to a square root
oh ok thanks i got it il try solve now
so if what im square rooting is negative what should i do?
i mightve gone wrong but i have x^2 = -305 and negatives cant be square rooted
wait nvm i did go wrong
It will be much less work if you get sqrt(9 - x^2) to the RHS first
Then square twice
If you want to, you can also make the substitution z = 9 - x^2 first
Then 16 - x^2 = 7 + z
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someone got me right
what's different between the graphs?
theres no graph
i mean equations

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does anyone have a nice derivation of this? I've searched for a while but I always see this just as an accepted definition. Ik this may seem super basic but this is a formula that has bugged me since high school and I always took it at face value, and now that im at uni the lack of intuition is bugging me more than ever
Variance is intuitively understand as a measure of spread, in the sense of how wide the values you get during observations will be
The obvious thing to do for that
Is I agree, not variance
However those definitions end up not having nice properties, so we use variance
Which is defined using this formula, and doesn't really get more basic than that
As for how to come up with 'this formula will probably do what we want'
X - μ measures how far off our observations are from the center, and the square makes that positive
(And introduces a weighting)
And then expected value so that we get an average
(The 'obvious' thing would be E(|X-mu|), that is just measure the average distance directly, but the absolute value makes it annoying and you can't use calculus, hence why we use a square instead)
well why didn't we define it using idk absolute values for example
yeah exactly
so the answer is just, "we did it like this cause its easier"?
E[(x-mu)^2] = E(x^2 - 2xmu + mu^2)] = E[X^2] - 2E[X]^2 + E[X]^2 = E[X^2] - E[X]^2
So you can also view it as:
The difference between the expected value of the square of the set and the expected value of the set squared
Uncertain, there probably are other reasons for it (e.g. I would expect it to have much nicer properties because of it being smoother) but I don't know them
A stackexchange post I found says that variance is more consistent (if you do variances of say 10 samples, then another 10 samples, etc. variance will vary less) with no source or proof
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Hi I’m trying to use ratio test to determine convergence or not but wanted to see if I’m doing the steps right so far?
yeah looks good
yea
Cool I’m getting stuck at the last line I wrote
Oh then it just is 1/n?
no
𝔸dωn𝓲²s
Oh yeah I see
𝔸dωn𝓲²s
Where would this go if you were to simplify the right inner term
Like after plugging in the limit?
Oh yeah does it become (1+1/n)^n?
yes!
I think we went over something like this and it equals e?
Infinity I would assume?
Oh I see then that is infinite still and that diverges right
𝔸dωn𝓲²s
it's not even a null sequence so it fails the necessary condition
Oh yeah I didn’t consider that either
Thank you for the visualizations, really helpful !
thank you too!
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What is the circumference of the circle?
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yes boss
npnp
yes
all help channels occupied
i made one
It says in my notes that the equation for this is O = s/r
where s is arc length and r is radius
that is correct
I was merely trying to guide you to find arc length
The arc length is 2, you're solving for theta. You can plug both known values in that formula you have there
its just 2/1?
So radian measure is just 2/1, and if i wanted the degrees that would be 180/pie?
Im just tryna review all the material for this quiz bc I dont understand this unit very well
Yes you would get like 2/(2pi) = d/360, whence d = 2*180/pi.
ok and when it asks for radian measure i just stop at the 2 right
It's also not especially intuitive that when the radius is 1, the arc length is the same as the angle.
So it takes time to learn and understand
that makes sense on paper
i just dont really get how theta works right now
or radian measure or wtv
Am i allowed to use this for multiple questions?
or do i need to close it now
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I don't understand how to do this at all lol. Professor never covered this and there's no video going over the problem.
if the sum of all the vectors is the zero vector you should be at the same point where you started your first vector
you can think of it as the displacement vector
What is a zero vector?
a zero vector is a vector of magnitude zero
it's simply a vector connecting two points which are the same
So am I making lines that form a resultant of 0
So a negative line and a positive line
well there's nothing called a negative line and a positive line
do you know vector addition?
geometrically?
Where two vector points form a resultant?
Like a and b give resultant a+b
That's about as much as I know for what I'm being asked
I'm not sure
This is video 3 of 6 from January 12, 2018
Oh I know this yeah
so try to add three vectors this way so that their sum is 0
I guess I don't understand how to do that on a graph. The only vector addition I've seen is like in the video where it's using letters.
And I can't connect lines like that on the homework site. It keeps forcing me to move the arrow around if I try to start a line from a vector point.
Oh nvm I got it working. Now I just don't get how to make the sum 0 since I've never done these involving numbers.
it has nothing to do with numbers
the sum is zero when the third vector ends at the starting point of the first one
I would need to see an example because I don't get it. Zero vector wasn't taught at all or mentioned in the class ever
And usually these problems have videos to explain what is happening but this one doesn't
I only know the vector addition from the video put. I don't know what zero vector means.
So when I see a graph and the only thing I know is vector addition with letters, I assume I need to form three lines that make vector x + vector y = 0 but that isn't correct
for two vectors the sum is zero when the two vectors have the same magnitude but point in the opposite direction
I tried that and it said it was wrong. So am I supposed to make six vector points on the graph for this since it wants three vectors?
why did you double it
cause isn't a vector formed with two "lines" and it wants three vectors that equal zero?
maybe I'm misunderstanding what a vector is
a vector is not formed with two lines
a vector is a line segment with direction
oh so the line segment itself with a direction is the vector?
okay I got it now.
so that triangle that is formed is from line segments with a direction which are vectors
the triangle isn't the vector
it's just made when you do vector addition
yup
actually a triangle is made of three vectors that add up to zero
okay I think I understand it better now
one quick question, what's an orthogonal vector?
orthogonal=perpendicular
they're synonyms as far as I know
would it still be orthogonal if you had two vectors with the same line segment length but one was negative?
like 2u and -2u
or is that impossible since they wouldn't be in the same spot on a graph
or nvm I'm thinking of parallel
2u and -2u are never orthogonal they are antiparallel
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Alex drives from point a to point b, then immediately returns to A bob drives from point b to point a then immediately reutns to b. They travel on the same road, starting simultaniously, each maintaining a constant speed. Alex's speed is three times Bob's speed. They pass eachother for the first time 15 minutes after the start. How long after the start will they pass eachother for the second time.
Looks like a question about comparing function, try making two and seeing when they cross
sorry what how do i do that
Wait no Nvrmd, try mapping it out using 15 min intervals on a numberline
but i dont know how long the distance from a to b is, and alex goes back to a after going to b and bob goes back to b after going to a
You just need to know the ratios, Alex passes Bob 3/4ths of the way to point B, because it’s 3x the speed
so they meet again in 20 mins?
Close but no, I don’t think so
if alex passes bob 3/4ths of the way to point b, and that was 15 min
3/4=15min
1/4=5min
alex time=20
bob time= 60
so
wait
Try mesureing via bobs time
So 4 intervals of 15 mins
Alex travelling 3 intervals in 15 mins
im lost
So Bob travels x distance in 15 mins right?
yea
And Alex travels 3x distance in 15 mins
yes
So In total, there is 4x distance between A and B
Now, if you put this into a number line, and count each persons distance per 15 mins, you get your answer
Yes, great job!
oh my god thank you so much
Whenever you get to problem like this, the best thing to do is figure what kind of problem it is: Ratios, Comparing Functions, etc..
ohhhh got it 👍
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