#help-0
1 messages · Page 692 of 1
You can either use the slope and go 4 to the left of t = 4.
Oh
Well, the slope is -50.
Yes
So y intercepy is (0,4) ?
When u go left by one it increases with 50
OK, so you know N at t = 4.
Yes
You can go to the left four times to get t = 0, right?
then at t = 0, it’ll be 1400
Oh okay i get these problems now thank you
What do u mean
Oh yeah true and for 10 it works too
Thnx i’ll double check them from now on too
No problem.
I’m going into 9th grade in a month and this is I ended with passing grades but not good, what are some things in math I should learn or prepare for for 9th grade?
everything of 8th grade..whats new isnt important now
@frank dome What math subjects have you learned?
Algebra, algebra 2, trigonometry, geometry, precalculus?
We mostly worked on lines graphs and y=Mx+b stuff and some inequalities I had to do online class for the whole year so I’m 80% confident working with them
Oh, OK, that's algebra.
We did do some algebra too
Can you afford like $40?
Also what’s a block schedule ?
imagine buying books
If not, I'd do Khan Academy algebra stuff.
Online course.
If you can afford it, I'd buy Schaum's Outlines "Elementary Algebra" and "Intermediate Algebra".
Schaum's Outlines have short explanations of how to do problems and then a bunch of problems and their answers.
Khan Academy (free) also has problems and will tell you if you got them right.
Though not quite as many problems as Schaum's Outlines.
Either way, you can get up to where you are now and start learning ahead if you want to.
You can also ask for help here if you get stuck on a problem.
you can find the book's pdf on google
isn't the copyright gone
if the author's dead or something
No, it lasts for like 75 years past death, unless it's owned by a company or something.
ah.
notice how the bottom is 2(1) then 2(2) then 2(3)...
the i is the part that's increasing (1,2,3...)
but you need the other part
i tried putting 2(i) but it didnt work
2i should work
try without parenthesis
different formatting
oh okay
eitohit parenthesis yes
yes
✅
Reading this book on linear algebra. What does det mean?
@final summit Determinant: https://en.wikipedia.org/wiki/Determinant.
Thank you.
5 stems from the fact that you can laplace along any row / column of A and get the same det, so A and its transpose have the same det
Got you. Thanks, Mosh.
Hey guys I'm kind of confused on this question. Shouldn't this be 2 instead of 1/2? Because wouldn't 1/2 be greater than 1/4? Think I'm not understanding the function.
it's 2 and 3/2
The book says the answer is 1/2.
$f(x)<x \ x^2-x<0 \x(x-1)<0$
Mosh
so the inequality is satisfied when $x\in (0,1)$
Mosh
Im still kind of confused on how its 1/2
cause 1/4<1/2
How do I approach this?
approach... what?
Oh I need to find the derivative
use the exponential form of cosh and sinh
that, or hyperbolic trig identity
$\cosh^2(x) - \sinh^2(x) = 1$
mchen10
I forgot how to do this
I took calc last sem
But make sure you find the der of each term
Then you isolote x and y
no, looks wrong
agreed, i did it out and i got something different

How do I plot a graph that looks like it’s twerking? Has to be one equation
@ me if you answer
Which step did I go wrong?
the first one
you applied the chain rule incorrectly
you need to add the parentheses because you multiply by the derivative of the inside
the lack of parentheses led to committing multiple math crimes
you should've just made the left side into a single fraction, then you can multiple the right side by 1+x^4y^2
and then it should be simple from there
distribute then factor out the dy/dx
you just look for the type of function it is
Yea but I’m not sure what the 4 functions are could you explain
i guess, but which ones have you heard of
that would be a step function
most of these aren't talked about in an introductory algebra course
This is a alg 2 course
oh
I’ve heard of the absolute value function
constant function is a function that is constant everywhere
Thank you
step function is the on ethat valentin sent
except step functions aren't continuous
Alright thank you
well yeah I kinda drew a curve instead of the function
just to clearly show the steps
It’s alright lol
basically, an absolute value function would only give you positive values
uh
shouldn't it be the other way around
why do u think the asymptote is y=1?
oh you're right
the graph goes down by 1
it's a negative 1
thanks!
👍
no
nein
multiplied by the whole derivative of the inner function,
NOT multiply by the first term of the derivative and then add the second term
agreed, it is also nice to recognize another great inventor of calculus, leibniz, who isn't really credited in the states
I don’t really understand dx/dy
You will realise y' just looks cleaner after a while imo
My professor taught it with y’
^
what about newton's notation
how so lel
i have horrible handwriting
1's begin to look like dashes
i can barely read my own handwriting sometimes
is this handwriting? looks nice
and in the heat of the moment (exam) u could really mess up
yes
help me to rewrite this pls
Umm
dont subtract something you need to multiply
you subtracted (1/(1+(x^2y)^2) when you needed to distribute
why not just make the left into (2xy+x^2 dy/dx)/(1+x^4y^2)
redo everything after the first step
Distribute that to every term in (2x*y+y’*x^2)?
you dont need to distribute the fraction
just multiple 1 by the derivative of the inside
So (2x*y+y’*x^2)/(1+(x^2y)^2.
yes
i would just leave the 2xy dy/dx on the right side since you are going to have to distribute the denominator anyway
you need to bring the fraction out of you want to take y' out
just your result from step 2 by (1+(x^2y)^2) on both sides
then solve
you multiplied everything in the numerator in step 2
it should be 2xy+y'x^2
and dont forget the parenthesis on the right side
you are multiplying the whole right side i.e. (y^2 + 2xy*y')
Isn’t that the same as 2x^3y*y’?
theres an addition and not a multiplication sign
yes now distribute and solve for y'
The right side?
yes
well if you try to factor it out that way, you would have to divide 2xy by y' in order to factor
the rhs is just adding y^2 + 2xy * y' to (y^2+2xy * y')(x^2y)^2
distribute then isolate the y' terms and then factor out the y' and divide in order to solve for y'
Would it be x^4y^2
yes
you forgot the 1 * y^2 in your distribution
Isn’t that what I wrote in the beginning?
(バカ) baka
i have put an unsimplified solution above
isnt y^2*1 = y^2
Using the fundamental theorem of line integrals i get either +50ish or -50ish which isnt even remotely correct? f(x,y) = xy+y^2 right? because gradient of f(x,y) = <y,x+2y>?????
it means that every 1 m^2 recives 1 litre of rain
anyone know how to do this?
nvm im a ***ing idiot
how
can i please have some help
dude
100 m^2 * 1 mm
= volume of the water
which is
0.1 m^3 of water
which is 100 liters
oh
Elonmosqito96
two different questions
oh'
srously
if object contains 150,000 electrons and 125.000 protons what is the charge of that object?
which one do you need help with
uhh you cant really "factorize that" but you can solve for x
I'm dying
yea
channel being used

i am just getting answers wrong
Wut? 
$$hogrider$$
Blue Dude
Average coc playa
$6 \sqrt {3} x + 7x = \sqrt {3}$
$x(6 \sqrt {3} + 7) = \sqrt {3}$
$x = \frac {\sqrt {3}} {6 \sqrt {3} + 7}$
Elonmosqito96
ohk
dont ping me please
and that is the same principle
Help me please
as this
$$whats-up-scoobs?$$
Blue Dude
$$shaggy-in-da-house!!$$
Blue Dude
I'm having trouble understanding pigeon hole principle
Like in regards to this question, you only need at least 2 cards
but the answer is like 5 cards because of 4 pigeonholes
however you can get like 2 cards in the start in one pigeon hole
It is possible to get two cards of the same suit
,calc 52/4
Result:
13
at least the probability for that is not 0, therefore it is possible
Yep its 5 cards
Clubs spades hearts and diamonds
I get it but there is antoher question that made me confused about the pigeon hole principle
Okay i get it, the question wasn't as vague as question i've seen before
And there is this one question which i don't get how they extract the answer for
I understand that you can't have 0 as the leading hence, it would be 9 factorial
but i don't get the reasoning behind multiplying the 9! by 9
how would that satistfy the non leading zero
How come?
Consider all the permutations, including the ones with leading 0s, which would be 10!
Since there are 10 digits each used once, exactly 10% of those permutations will start with a 0
So only 90% of the permutations satisfy the condition
90%*10!
= 9/10 * 10!
10!/10 = 9!
So it is just 9*9!
Such that each student shakes hands with each other student?
yeah that is where i'm confused
i am confused with the line of why two students will each have shaken the same number of hands
Yeah
Well in the answer it says "Each student shakes hands with 24 other students, so 24 pigeonholes for 25 students, so two students must have shaken hands with the same nubmer of students."
it is saying that 2 students must have shaken hands with the same number of students
i am confused, so each student shakes hands at least once
Hello what class would you guys pick for someone who is ok at math? College Algebra or Pre calc?
however the answer says that 2 students msut have shaken hands with the same nubmer of students
So there will be of course 1 person left out in shaking hands
why does this show that two students must have shaken hands with the same number of students
I am still quite confused how could this lead to two students must have shaken hands with the same number of studens
like i would of thought that would mean that there is at least 1 person who have shook a person twice
No student shakes hands with the same person twice
Okay with that condition, why would it be that 2 students would have shaken the hands of the same number of students
It actually doesnt have to be 2
like how could he of shook 25 people
Just more than 1
The boxes are numbered 1 thru 24
So if you have 25 people then one box will have more than one person
I think i'm starting to get it
so how i'd imagine it
you have 24 boxes line of up in a row
and then you have 25 students filling in with each of the boxses
however due to their being only 24 boxes
there would be a box with at least 2 people in it
and that 2 people would have the same amount of hand shakes
but the only problem is, wouldn't the odd one shaking with some other guy would mean he would of shook twice
unless all of them shook three times
and then it would mean that the two students would have 4 handshakes
Like shook three times for the same person
Do you think this is correct or not?
Yes
precalc is typically one step up
Okay thanks
This is called the "pigeonhole principle"
And in fact it doesnt matter if someone has not shaken hands
Because then it would just be from 0 to 23
Instead of 1 to 24
If someone has 24 handshakes then they have shaken hands with everyone else meaning that everyone has at least one handshake
hello, is this channel now free to ask?
Sure
ok

here
well I already have my answer which is 4/5
i don't know if it's right or wrong because there is no answer key to it and i'm dumb
if you want to know where i got my answer well sure thing i can explain
that question is phrased so weirdly
i think it means neither couples are next to their respective partner?
based on my understanding it seems so
also yeah i hardly understand this question at first
do you know how to approach this question?
i do
if you want me to show my solution sure thing
oh if you alreadyt have the solution and just looking to verify sure
ok thank you
if my mental maths is right it's close
,help
A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!
I believe its 5/6 but show me ur solution bc i could have fumbled the math in my head
ok give me a min
channel busy dude
i already have it covered lol
ok
im sure someone needs help in another channel though
2!2! * 5 is the amount of ways they are not seated together
5! is total ways
let P(a) be the probability that neither of the couple sits together yada yada
P(a) = 1 - P(a')
Instead I'm just going to calculate the complement instead
So there are two couples lets call it couple A and couple B
the ways couple A can be arranged is 2!
same goes for couple B
let's call the single person C
the ways A, B, and C can be arranged is 3!
so overall the number of ways are 2!2!3! based on the condition
the total number of ways is 5!
so the chance is 2!2!3!/5! which is 1/5
subtract it from 1 and i got 4/5 which is my answer
i'm sorry if my explanation is terrible
That's a little convoluted lol, the method of calculating the compliment was correct though
that is the proper approach
let me draw something real quick
can we agree this sort of pattern
is the only way no couple can sit together
wait there are 5 people right?
with the random person somewhere in there
yeah just imagine they are between one of them
or on the end
oh ok
im wrong
woops
they can
i said something stupid
mental maths failed me, the second i drew something i realized i was wrong
i think the random person can seperate a couple
just put them inbetween i think
are y'all doing combinatorics?
your working is correct
i would of done it a different way but this is completely fine
the math is all correct
good job dude
so is my answer correct?
yeaha
oh thank you dude
A boat is to be manned by 8 crew members of whom 2 can only row on bow side and 3 can only row on stroke side, total number of arrangements possible?
@bronze dust Pick the places for the stuck members.
Arrange the nonstuck members in the remaining places.
So, there are four places each side.
how about i do it like this
there are 4 places each for bow and row
5 members are restricted to either bow or row
i select 2 unrestricted members out of 3 unrestricted members for bow side (i need 2 there)
then 1 unrestricted members out of remaining 1 unrestricted members for row side ( i need 1 there)
and then i arrange bow and row seperately
3c2 * 1c1 * 4! * 4!
is this correct?
3! * 2! * 3!
i thought
i mean like you can assume there's 3 boats, one for 3, one for 2, one for 3
why this?
i don't understand the task
3 restricted is 3! and 2 restricted is 2!
the remaining is 3 unrestricted, so 3!
ah ok, 8 spots, 8 people, i get it
that's just what i think but i'm not sure
i think thats wrong
wait idek what bow and stroke are
add another 2! here
@bronze dust No, you have too few possibilities because you don't account for the ways of placing the nonstuck people in various sides. You just assume they're already sorted to sides.
(4c3 * 3!) * (4c2 * 2!) * 3!
@oak chasm what is the correct answer according to you then
If you're asking me then I would say mark the correct option. 
thats my first answer too
but i guess we have to multiply it by 2 as well
to account for both arrangements
RBRBRBRB
and BRBRBRBR
sure
b = bow, r = row
@bronze dust I've checked with a program and it looks like your answer was correct.
There are 1728 suitable arrangements.
and multiply it by 2 also right?
what if pattern starts with green
i think not
u basically do it like 2 3 2 1 = 12
for part b
i think its 3(4!)(2)
oh its hould be 1 2 3 2 so in then end u need 2 even numbers to be even
you have 4 choices on the first 3 digits, and only 2 on the last
the answer is 128
i think or this u need to 4 x 4 x4 x2
oh wait my bad-
cuz
2 even nmbers
yeah that thing is right
yea
Okay i get it thanks
then multiply it by 2 for the last one
and also for the division by 2 right
is it determined based on a ration within the set
like forexample you want to calculate a 4 digit number that is greater or equal to 4 for the first digit
i mean like how many combinations can you make with a 4 digit number that has the first digit being greater or equal to 4
it would be like 75 percent times 4^4
um kinda-ish?
I honestly don't get what you mean sorry
Like what if the question is that you want to find the permutation of a 4 digit number from like 3,4,5,6 and that it must be greater or equal to 4000
it would be like 75 percent
of 4^4
can you tell us where do you get the 75% thing
I want to get this straight
oh ok...
So for the front seat, there is really only 2 people that are able to sit in the front
because there is only 1 person which is the driver is able to sit there
as well as fixed people in the back
so it is basically 4! [For the switching from front seat and backsword in between of the 4 people] * 4! [people swapping around in the back]
but the answer is 288
which is half of the result here
,w solve 4! * 4!
I am looking at the answer and they made it such that it is 4*3 * 24
and they got 4*3 because "only four are able to sit in the front passenger seat"
Is this because once you find out how many permutations for the front seat, it would mean for the one seated at the back
like there are 10 strawberries, and you ate 4. And because you know you ate 4, there are 6 strawberries left
But the problem is with my solution is that it is repeating
Is this correct?
u can divide this experiment into two
- choosing 2 out of 4 to seat in the back seat
- choosing 2 out of 3 to seat in the front seat
since u are essentially taking away the 'particular people' who will seat as given
e.g. we choose only 2 ppl to seat in the back seat because 2 out of the 4 slots have already been taken by the particular ppl
similar logic applies for the front seat
Question: If $\log{x} + \log{y} = 6$ what is the minimum value of $x+y$?
oño
I got 2000 but idk if 2000 is correct. I got it by assuming x=y
u still need help ?
yeah im not sure with that answer
I think I got something that might help ya
Do you know the Sum to product rule of logarithms
yes
I would like to know what you have in mind
I think its where Pajo is going
Uhhh how do I do Q14
yeah
And then y = 10^6/x
thats where i was going
ohhh I see thank you
so first write 7 1/2 as a fraction
yep
then what
now you need to see how many blocks your going to have
do you have an idea how you re gonna get that
nope, not at all
so if you have 10 acers and you divide them in to blocks of 2 acres
how many blocks of 2 acres will you have
wait how is it 10 acres
im just giving a simpler example
oh
the principle is the same
oh, okay
after converting the mixed numeral to a improper fraction
we finmd the amount of acres right
but how many acres are in the question
nah we find the NUMBER of blocks of the requested size which is 3/5
how do u do that
okay thats why i was asking this
the one u asked or the one i asked 😄 ?
the one i asked
15/2 : 3/5 = 15/2 * 5/3 = 25/2 => 12 minus the 2 for the frogs so 10
im confused at that part
what do u mean by 12 minus the 2 frogs
ohhhhh
i get it
ok
mkay tysm
:]
is there any way to simplify 3ab-2 further? we have this speed solving activity in our math club and i said "cannot be simplified" yet they marked me wrong...
3ab-2 ?
not as far as I know
you most probably made a mistake somewhere before that
a tractor puts a force of 1000N the pressure exerted is 40Pa find the area in m square
can anybody help?
h mm
The formula for Pressure is Force = Pressure x Area
So you just have to rearrange that formula and then put the numbers you were given into it
I don't get why it is just 5!
and not 5! *2
because you are making one of the judge the point
and not the entire judge becoming as one unit
therefore within the 3 groups, they are able to swap around
Nevermind, thank you
u sure its 5! ?
I reread the answer it is 5! * 6
6 in which they permutate within their small group
I don't get how we can approach q22 b
you can just subtract the cases where they r together
you'll get the number of cases where they're separated
I got the answer for this but I want to look for a more efficient way
Yeah, i just found out the cases when they are together
That is good
👍
number of ways in which they can be arranged when no conndition is given is 5!
Okay i got it
k
I thought the answer for a would be 24
oh
wouldn't it be 6! if no condition is palced
circular permutation
(n-1)!
u re right
can anyone tell me how to calculate imperfect roots without calculator
any root or just the square root
any root including sqrt
I just came to alg1 so..... pls dont include any alg2 ehh......
well boy if you dont know calc i cant help u sorry
uhh k
there could be a method i just dont know it sorry
You can usually get a rough approximation by assuming the values are evenly distributed
ex sqrt(7)~2.6
how did you calculate
7 is between 4 and 9, so sqrt(7) is between 2 and 3
ohk that thing I ve studied
7 is the 3rd integer between 4 and 9 out of the 5 total ones, so it's 3/5 along
so 2+3/5
,w sqrt(7)
dont crosspost.
Hey man something just came to mind
do you know how to do polynomials
umm no
but going to study
in alg1
i have that in my textbook
ohhh too bad I just rembered lagranges interpolation polynomial for aproximating functions
whats it
can I ddo it
in alg1
not without polynomials
yeah
We show you the method of solving for the Lagrange interpolating poly without having to remember extremely confusing formula. Just follow our method!
TimeStamp !
Now try to solve it on your OWN! Don't just "understand"... PRACTICE!!
...
Lagrange Polynomials / Interpolation is a uni concept...
Really ?
sorry then
will try
Yes, at least I only learned about them in linear
Bye I am going to spam my textbook to reach polynomials
we did it at end of HS
as it requeires calc only to find the error
something he doesn't seem to be concerned with
Told you already.. stop crossposting
Please don't post the same question on different channels
Please only ask when a channel is free
Please translate it in English.
...
Dw I took care of them
Help please
sum of angles in a quadrilateral is always 360
you can find BDO and BEO
oh oops
brainfart
will BDO and BEO would be 90?
yes
alr thanku
I am having trouble in obtaining the answer for this question
The last part for which the two particular artist must not sit next to a particular writer
So i was tryinng to find the case when the artist sit nexts to the writer
and then minusing the case where there is no restriction
so i did this $2880-4!\cdot3!\cdot2$
Travelling Salesman
but unfortunately i did not get the correct answer
2880 is from no restrictions
and the 4! *3! *2 is the total permutation of when the two particular artist are next to the particular writer
I think i didn't take the case for which one of the artist is sitting next to the wrtier
Still confused
How to solve this?
4! * 5!
is this the answer?
Neither of them want to sit next to the writer, it doesn't have to be both
How to calculate w
isnt that just the whole square minus the 310° arclength minus the triangle ABO ?
prob use pythegoras theorem find the area of the triangle ABO
i just need to find w why would i find area?
no it's the base of the rectangle
sorry >.<
The answer is coming 11.4
no worries
you can get x using cos(theta) here
theta is 35 degrees
(i'm using the angle bisector of <AOB
yes i did that but will i multiply it twice to find w, or add 6 into that
No, it's 25 degrees. (360 - 310)/2
why
mb
can i not multiply it?
Oh ok thanku
You don't know if that's some sort of midpoint.
There isn't really enough information.
You can tell that the x value of R is greater than 6. You can tell that the y value of R is greater than 5 and less than 10.
cant figure it out unless they said they were midpoints 
You can assume that the points are drawn to scale and use a ruler, I suppose.
But in your answer, you should write that you're assuming the points are to scale.
ok i try that
ello i just land to this server
im 14 years old . i really like math tbh . i found this server by searching it :D.
lol same
this server contains some highly complex questions which are out of my scope lol
nice. and hello there
Hello
yep
im top 10 for form 2 student
for math only tbh
:/
i suck at langguage
lol
found the value for x in R but not so well in y
couldn't get you
lol, I am preparing for an engineering exam... so I only have to focus on Math , Phy, Chem
owh nice
good luck
@crimson raven Well, use a ruler and find the vertical distance between P and U.
Thanks : )
hol up
np =).
@crimson raven Is that the same distance as between U and S?
a sec
how couldnt i didnt notice this
if X is midpoint of RQ
then RX=6/2=3m
and 4+3=7
ik
I mean measure with a ruler.
seems not kinda legiting but do it anyways
Is XV the same length as VR?
Right, that's why you have to write "assuming everything is to scale"
measured and yes
OK, here's how I'd answer it:
Assuming everything is to scale, R is approximately (10, 6)
If everything is not to scale, R's x coordinate is greater than 6 and R's y coordinate is strictly between 5 and 10.
Do you know what "to scale" means and how I got the second part's numbers?
for x bc it lies on the right side of P so value of x should be greater than 6
Right.
Well, it has to be greater than U's 5. And the height of the rectangle is 6, so it can only be 6 above P's 4.
Does that make sense?
kinda
If it was greater than 10, it would be more than 6 higher than P, right?
yes
But the rectangle is only 6 high, right?
yep it says that
if P lies on under the line would be impossible
Right, P would have to be under the rectangle.
Another way to see it is that the bottom of the rectangle is under P's 4, right?
yes
So, if you add 6 to the bottom of the rectangle, that's under 4 + 10.
Wait.
That's under 4 + 6.
,,
@dense violet Sorry, channel is busy.
Let me start again.
The bottom is under P's 4.
The top is 6 higher than the bottom.
The top is under 4 + 6.
The top is under 10.
Does that make sense?
kinda know the concept
like 1cm to 1m, 1:2 or sth
Yes. "To scale" means that you take an exact picture of the thing and then you exactly scale it up or down.
So if two things are the same distance apart on an exact picture, they'll be the same distance apart if you exactly scale that picture up or down.
So that's why we can use a ruler.
If the ruler says that the distance between S and U and U and W are the same, then when we scale that up to the exact picture of the real thing, the distances will still be the same as each other, just scaled up.
Does that make sense?
yep
That's why we say "Assuming the picture is to scale" so that, in that case, we can use a ruler.
And that's why we also say, "But if it's not to scale, then this less exact result."
Then we've covered all the bases.
Consider in an orthonormal coordinate system a circle passing through point B(−1,0) and tangent at point A(1,2) to the line with equation y=2x. What is the area of this circle?
Could someone help me out please? I'd very appreciate it.
hey guys. might seem really random, but does anyone know where i can start learning about the Whewell equation?
This channel is taken ._.
@eager surge Sorry, channel is busy.
oh my bad. do you know where i should ask this question?
thanks
Consider in an orthonormal coordinate system a circle passing through point B(−1,0) and tangent at point A(1,2) to the line with equation y=2x. What is the area of this circle?
Could someone help me out please? I'd very appreciate it.
<@&286206848099549185> Anyone?
@spring harbor Well, one of the basis vectors could point in any direction.
So, let's see.
You have A(1,2) on the line y = 2x.
Mhm
@alpine sable Sorry, channel is busy.
oh sorry
@spring harbor So, the direction of vector A has to correspond to the direction of the slope 2.
So, that's 2y per x.
So, A(1, 2) is also 2y per x.
Now a slope points in two directions from the origin.
So, the basis vectors are either (1, 0) and (0, 1) or (-1, 0) and (0, -1).
Does that make sense?
I mean.. sure, but we're not really supposed to do this with vectors
I think we just have to make usage of some basic concepts like the circle equation and other things
Yeah I am really thankful but i'd rather do this in a method I understand, I don't want to just nod my head and go along with what you say
We learned how to use vectors and such but not at the level you're showing there (i think at least)
That's trigonometry.
HI, i need some help with a problem
Chai T. Rex
@viscid compass Sorry, channel is busy.
For the x component of A in the standard basis, you add together the x component of the rotated components of A in the orthonormal basis.
An orthonormal basis will just be the standard basis rotated somewhat with the components reordered perhaps.
@viscid compass u can go to #help-7|zen1thxyz
@oak chasm I handed in without giving an answer and this is part of the solution they showed
@oak chasm may* I ask what you just did?
So they got point M(-3,4)
and then they found the length of |MB| which is sqrt(20)
and used that to find the area of the circle
but I am not very sure I understand the first step, how they got the first two equations
they are the tangent line equation I know, y-f(a) = df(a)(x-a)
but im not so sure i understand why they used it *in the way they did
consider the fact that tangent is perpendicular to radius
Fair, so their slopes multiplied gives us -1
yep
it needs to pass through (1,2)
Hmm
it is the line along radius
but it should be f(a) there
passing through (1,2)
I understand 2 but why 1
a line with slope -1/2 passing through (1,2)
yeah no im totally lost
xD
The -1/2 slope comes from being the perpendicular slope to 2.
draw the center of the semi-circle, connect it to the tangents, get a square.
connect the radius of the large circle to the corners of the semi circle. See what you find.
Oh I see
what about the -1?
Not sure about that.
(y-2)=(-1/2)(x-1) slope-point form of line
It looks as if they're making equations for the lines from A and B to the center of the circle.
But I don't know how they know the slope is -1 for point B to M.
does not make sense to me either
but you can get a different line
perpendicular bisector to the one joining A and B
"A tangent to a circle is, at the point of tangency, perpendicular to the radius of the circle through that point. We therefore find the center M of the circle as the intersection of the perpendicular in A on the line y=2x on the one hand and the perpendicular bisector of the chord [AB] on the other. To find this intersection, we need to solve the following system:"
google translated so dont mind it very much
ohh wait that is exactly what it was
Ahh, OK.

misread y-1 = -1(x-0) as y = -1(x-1)
How did they convert the slope for the standard basis (2) into a slope for the orthonormal basis?
no clue
orthonormal coordinate system implies standard basis
No, it just says that the basis vectors are unit vectors and orthogonal.
They could be rotated from the standard basis.
I think it means a cartesian coordinates system
Like if I rotate the x and y axis by 30 degrees clockwise, it's still cartesian.
And the basis vectors are unit vectors and orthogonal to each other.
(1,2) how would you interpret this position vector in your system
Yes, that's what I mean.
I mean, I showed earlier how to do it, but I was wondering how they did.
(1, 2) has a slope of 2 as well in the orthonormal basis.
So, you don't need to convert, but they should show that it's that way.
For this one, everything's rotated 180 degrees: https://www.desmos.com/calculator/fw7y6v96lq
since every vector is rotated equally and they didn't ask for actual coordinates just the radius , you can use this solution WLOG
Well, the problem is that the coordinates are in the orthonormal basis and the slope is in standard basis.
You need to convert the slope into the orthonormal basis.
This only converts without change if the rotation is 0 or 180 degrees.
Otherwise you need to do an arctangent to get an angle from the slope, add the rotation, and use tangent to get the slope.
No, the points are said to be in the orthonormal basis.
But x y is standard basis.
I think it's just a mistranslation
Could be.
it's just a cartesian coordinate system
Oh, I didn't know that that was for sure.
its a communication problem on their end but when they don't mention any other frames(using cartesian terms) and mention (y,x) its for a general point
thanks for the help though, both of you.
No problem.
MEOWBRO 父
and you are asked to show that sin 2x does equal the right hand side
but!
you can only use these formulas
you cant do any cot or sec
etc
id perefer if someone can walk me through it step by step and like ask me questions
but ill take any help ofcourse
Take everything in terms on sine and cosine
sin(x) and cos(x) to be precise
Then, instead of using sec you can use 1/cos, etc. so, for example: 1 + tan²A = 1/cos²A
What
well if they show you sec you can do that, but it looks like they didn't cover sec
exactly!!!
thats the point
don't worry too much
I'm saying you can leave everything in terms of cosine without converting to secant
thats the problem*
if it doesn't show up then you don't use sec
then you don't need to use it
they only solve these questions with sec and stuff
Then don't copy off of YouTube.
and i have no idea
i cant find a single youtuber that doesnt solve it without sec and other stuff
Well, there you go I guess
are you just giving answers here
When asking for help, do not insist on getting just the answer; we are here to help you learn, not cheat. Likewise, if you are providing help to others, try your best to explain and elaborate instead of simply giving away the answer.
Let f(i) denote the minimum positive integer x such that x is not a divisor of i. is there a term for this??? I have some problem in programming regarding this.
there's no mathematical term for that i think
unless you mean mex
mex {k | k divides i}
In mathematics, the mex of a subset of a well-ordered set is the smallest value from the whole set that does not belong to the subset. That is, it is the minimum value of the complement set. The name "mex" is shorthand for "minimum excluded" value.
Beyond sets, subclasses of well-ordered classes have minimum excluded values. Minimum excluded v...
@next scroll ?