#help-17
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more context would help. e.g. an example
@lethal flower Has your question been resolved?
Lets say we have the set of binary numbers in 4 bits: {0000 to 1111}
If I focus on the first and second bit, there are 4 possibilities: 00, 01, 10, 11.
For 00, there are four 4 bit numbers ( group 1). For 01, there are another four ( group 2). For 10, there are four ( group 3). And for 11, there are four ( group 4.)
By considering the four permutations of the part, and putting the groups together, I get the entire set of 4 bit numbers back.
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Now can this be applied to a general situation?
My problem is this:
I have a set S that has all the possible results of 5 people in a class.
Every element in the set is the combined result of the 5, in the form:
person A -- pass/fail
person B -- pass/fail
person C -- pass/fail
...
person E -- pass/fail
now if I take four subsets:
subset A has all the results where person A has passed
subset B has all the results where person A has not passed
If I unite the two subsets, do I get the entire set S back?
yes
Can you elaborate?
either A passed or didnt
Why does the union of a part's permutations lead us to all the outcomes?
the results will be in one of the sets
but why does exhausting the possibilities of a small part give us the entire answer?
this is the same as doing bitstrings of length 5, yes?
so subset A is all numbers starting with 1
subset B is all numbers starting with 0
every number starts with one of those two
It is a property of every number, true
But if we take the two, why do we get every number?
Why is the reverse true?
tell me a number I dont get
Let's explore this generally
But this is experimentally looking at the thing
Which principle allows the two to give every number?
the law of excluded middle
well every number belongs to one of the two sets. so combining the two sets gives every number
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I get thatx=a
And
Y=b
I just dont understand
Xa sand all that
How am i supposed to know if they cross
Why??.??.
???
Huhhh
Do I even know you?
also they don't give you the exact coordinates of point P
Are you being sarcastic?
no
Wait so they all pass bc they cant be zero
that's right
well, they all pass because a and b can be whatever you want them to be
positive or negative
they don't specify (further) constraints
Interesting
Agreed
But i think if you take what they want you to take it should be D
why D though?
No no he's right they haven't said a and b are distinct
what question are yall discussing
Because point P is (a, b)
Like assuming a and b are distinct
And if u put in thode valued
this? It says a,b not equal to 0 and P has coordinates (a,0) just satisfy and check condition
P is (a,b) correct?
drugs
Yeah
no
I will math is fucking w me
What
So put the coordinates of P in all thr given lines to check which one passes through P
Only D satisfies
Also the fact that they've mentioned the point P is in 4th quadrant HAS to mean that a is positive and b is negative
Ohhh yesh i trief it worked
Good
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Cold somebody help me according to the answer key I got this very wrong but I don’t know how to determine if a graph is son of cos
if you remember the definition from the unit circle
then you can see that sin(theta) starts at 0 when theta=0 and then increases as theta increases (and decreases as it decreases) for theta near 0
Whereas, cos(theta) starts at 1 for theta=0 and initially decreases as theta increases or decreases
that should be enough to tell what is cos and sin in the picture you sent
The thing that is confusing me is why are the y intercepts not (0,0 ) or (1,0)
Oh wait nvm
How do you know when theta is 0 and theta is 1
you can find the point on the theta axis where it is 0. then you can check what the graph is doing for theta values near 0
My teacher was not here yesterday so we had to do the work on our own so that’s why I’m confused
What’s a theta axis…
the axis that has the values of theta (the horizontal axis in the pictures you sent)
Sorry I’m really confused because none of the graphs start at 0
And only one starts at 1
the graphs don't start at 0 (i.e. not intercept) but there is y value when theta is equal to zero
why does the 1 matter? I'm just trying to discuss how to distinguish between cos(theta) and sin(theta) using the shape of the graph
maybe we can do one as an example
I mean if the y intercept is (1,0) it is cosine and if the y intercept is (0,0) is is sin or tan
And then the intercepts for cosine is pi/2 and 3pi/2 and the intercepts for sin is 0,pi, and 2pi
this is true (I think you mean (0,1) though instead of (1,0)).
Let me explain a bit better.
All your graphs are of the form a*cos(theta)+b or c*sin(theta)+d
I want to teach you a way to distinguish whether it is cos or sin without using intercepts
the way you can do this is to consider what the shape of the graph looks like near theta=0
nothing about intercepts
Oh yea
I meant 0,1
just how the graph changes as one decreases or increases theta a little bit
yes, or moving to the right on horizontal axis
so like here
The graph is initially increasing as theta increases from 0 (I can see this because the graph starts at -3 (it doesn't matter where it starts) and it moves upwards as I look from theta=0 to theta=pi/2)
How would we be able to tell it is an increase and not a decrease?
okay great!
so we just want to be able to tell if this graph is of the form
a) a*cos(theta)+b
or b) or c*sin(theta)+d
well sin(theta) is increasing as theta increases through 0
whereas cos(theta) has a maximum at theta=0
the graph clearly does not have a maximum at theta=0 so it must be c*sin(theta)+d
and then I think you know how to work out c and d
Wait how would we know if it’s sin or cosine
because cos(theta) has a maximum at theta=0
so a*cos(theta)+b will also have a maximum (if a>0) or a minumum (if a<0) at theta=0
but the graph above *doesn't * have a maximum there so if it's either sin or cos it has to be sin
But a non translated cosine graph before this new homework has a max at 1 or more
For theta=0 cosine shows max value
cos(x) has a maximum value of 1 at the point x=0
So how would we know what a theta maximum is?
I'm not talking about the value of the maximum, but rather at what point on the horizontal axis corresponds to it
see the graph at (0,0), these is max value on y-axis
Ohhh
a*cos(theta)+b does not change the location of the extreme points (i.e. maxima and minima but it does turn maxima into minima and the other way around if a<0. that doesn't matter though for the purposes of this question where a>0 always)
So a theta max/min is just the max/min at the y intercept?
roughly speaking yes, but let me clarify:
a function can have multiple maxima or minima
there is a maximum value of the function a*cos(theta)+b at theta=0 (since a>0 for all your examples)
But that's all we need to worry about for the purposes of this question
like cos(theta) also has a maximum (value of 1) at theta=2pi
but we only really need to worry about whether there is a maximum or not at theta=0 for the purposes of this question
How would we know if we don’t know if it is sin or cosine? Since that would change if it is 0 or the corresponding point
if it is sin then it doesn't have a maximum at theta=0
if it is cos then it does have a maximum/minimum at theta=0
So you can look at the graph, ask: okay is there is maximum\minumum at theta=0?
if yes, then it's a*cos(theta)+b
if no then it's c*sin(theta)+d
So graph 1 and graph 3 would be sin and graph 4 and graph 2 would be cosine?
exactly
So once we know that we can just use the amp and midline to find the right equation
yep!
Ty!
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Can anyone solve question no. 1 c that is asking for Quartile Deviation coefficient of Quartile Deviation please somebody can do it please
Can anyone solve question no. 1 c that is asking for Quartile Deviation coefficient of Quartile Deviation
Can anyone solve question no. 1 c that is asking for Quartile Deviation coefficient of Quartile Deviation can someone please solve this please 🥺
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I want someone to explain the gradient matrix and the equivalent gradient matrix line by line for me A
@strange void stop spamming channels
I've closed the newer one you made
stick to this one pls
also in the help channels you shouldn't ask for people to explain concepts, cause well there's a lot of textbooks and YT videos floating around on the internet
if you want to use us humans wisely, ask a question about an exercise you have
or like a part of a video that you didn't understand
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I have an order of operations question. Which option in the photo is best for solving an area of a circle?
When I have (4/2pi)^2, what are the steps needed to solve? Why are the solutions different between the two different steps I took to solve? Which one is right?
Result:
0.40528473456935
,calc (4^2)/((2pi)^2)
Result:
0.40528473456935
however you're calculating this is a mistake
Result:
6.283
k is right. please review order of operations
https://www.mathsisfun.com/algebra/operations-order-calculator.html
Type in your sum to see how to solve it step by step. Examples 234 or 3/43 ... Just type in sums like these (see Order of Operations for more detail)
Learn how to calculate things in the correct order. Calculate them in the wrong order, and you can get a wrong answer!
Thank you!
Yeah what I’m learning here is that I need to use more parentheses when plugging equations into my calculator (TI-84)
I’ve been playing around with the parentheses I use in the calculator, and I’m getting different answers depending on the parentheses I use
.
So is my equation wrong here at the top of my page bc I don’t have the parentheses around 2pi? Or is it just that equations have to be plugged into calculators more specifically?
the top equation is not wrong, but when you enter it into a calculator as 4/2π the calculator reads that as
4 / 2 * π = (4 / 2) π
so to enter it into the calculator correctly you need to either use
4 / (2π) or 4 / 2 / π
or use the fraction mode (alpha -> F1)
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no one help me
what do you need?
I want someone to explain the gradient matrix and the equivalent gradient matrix line by line for me A
ok i don't know
i just know that it's a matrix with all the partial derivatives
i guess
@strange void Has your question been resolved?
@strange void Has your question been resolved?
@strange void Has your question been resolved?
@strange void Has your question been resolved?
send example of your gradient problem, maybe a screenshot
@strange void Has your question been resolved?
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How can i get the f(x)=
Do you know what sinusoidal functions are?
A sinusoidal function is a function using the sine function. The basic form of a sinusoidal function is y = A sin (B(x - C)) + D, where A is the amplitude or height of our function, B is the change in period defined by 2pi/B, C the horizontal shift, and D the vertical shift.
No i sont think so, but im german so maybe i know the german word
here
hi, if you can hire me, I will sovle your every problems. thanks.
Okay you know what sin x is right?
Wym by that
For which one
,calc pi
Result:
3.1415926535898
π
@wicked grotto Has your question been resolved?
you're talking about y = A sin(Bx - C) + D then
,rotate
it's also y = sin(2x)
so A = 1, B = 2, C = 0, D = 0
,rotate
this other one is trickier, cause the phase shift is hard to figure out from the graph
I don't think he knows what sine is
So thats the right one?
yes
because d is (max + min)/2
d is the average value of the trig function
oh I wasn't doing that question
I was still on this one
Oh mb
okay, if you're moving on then
the maximum for the 2nd question is indeed y = 1.5
and the minimum is at y = -1.5
so which letter does that information relate to: a, b, c, or d?
A =1.5 , b =1, c =-2/3pi, d=1.5?
I don't think you understand what d is
d = 0
but yes the period is 2pi, the exact same as sin(x), so b = 1
it helps if you use a few words to support your answer
I did this for d
so y = 1.5 sin(x - (-2pi/3)) yep
Oh now i get d
Ty for help
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np!
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i'm a bit confused about this - does it just want me to solve it algebraically?
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this will be difficult!
better to realize your polynomial has real coeffs
thus (z+sqrt(2)i) will also be a factor.
thus (z^2+2) will be a factor
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Rocío goes to the bakery and buys for breakfast 3L/ 2 + 4 loaves of bread, knowing that
How many loaves of bread will she buy for lunch, if she buys three loaves less than at breakfast?
she buys three loaves less than for breakfast?
@vast shale Has your question been resolved?
$ab = \frac{6^{1/3} - 4^{1/3}}{4}$ right
south
difference of two squares
then if you can find what (a + b)^2 - 2ab = a^2 + b^2 is
a^4 + b^4 = (a^2 + b^2)^2 - 2(ab)^2 and that's enough information to figure out what (a^2 + 3b^2)(b^2 + 3a^2) is, after you expand it
@vast shale Has your question been resolved?
oh right
(a + b)^2 - ab = a^2 + b^2
I don't understand how they are equal... (a + b)^2 - ab = a^2 + b^2 + ab
is it necessary to know this in ordet to solve it?
I havent been taught that one btw
I could deduce it tho
is this correct?
- a instead of b in one
maybe there is no need to replace it
like that
What should be my next step? and what am I doing wrong?
<@&286206848099549185>
what I'm suggesting is yeah that exactly
so if you find ab, you know (ab)^2
and this is how to find a^4 + b^4 with the information you have
a^4 + b^4 = (a^2 + b^2)^2 - 2(ab)^2
oh ok, so this is like an equivalence
yep, this is an identity
in fact it should be 1/2, cause 1/16 * 4 (6 - 4)
weird, L should be equal to 2
why (6 - 4), from where
I can check using Desmos one sec
,w (a-b)((a-b)^2+3(a+b)^2)
let p = 6^(1/3) and q = 4^(1/3) for convenience
then after expanding you should get 4(p^3 - q^3)
if your original expression is correct ofc
you should get $\frac{1}{8} (p^2 + 6pq + q^2) = a^4 + b^4$
south
from $\frac{p + q}{2} = a^2 + b^2$
south
mm I didn't get this
this looks a little bit like the identity I didn't know
But it's different
sorry, I need to regain my math habilities (all precalculus), which I studied last year, I stop practicing many months ago (been moving to another country and learning languages) and I'm revising from the beginning
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How do I solve this using the method with the positive and negative thingy (I tried but made some stupid stuff)
Wdym the positive & negative thingy o.o
(-5) times the first equation, (2) times the second equation. Then add them up
Is x=21/6???
i have no idea
dude i dont have the answer
What book is this from
-60 + 20 = not -5
why
Cuz i asked
Are the questions asked separately? I mean 2x+3y is question A and 5x+4y is question B. If so maybe I can help
i looked up exercises on youtube coz i have an exam tommorow from this
bruh this is the same question its just the work i did but its wrong
Wow. Wise move
Ouhh
First equation, its 45 not -45
-10x - 15y = 45
10x + 8y = -10
So -15y + 8y = 45 - 10, -7y = 35, y = -5
Plug back, 2x + 3*-5 = -9, 2x = -9 + 15 = 6, x = 3
@mystic crater
Could you understand each step
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wait
Yes?
no nothing i tought the command didnt work
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Can someone explain part d
There steps and my idea was let u =sech^n(x)
Then substitute the mclaurin seried of sech^n(x) into the mclaurin series of E^x
Im not sure if that would work, would it? And what did they do?
Ping me when u respond
can you take a picture of just the questions
the text is too small
Ah sorry
I wanred everything im 1 ss thars whg
@bronze osprey
<@&286206848099549185>
that works!
so you just sub in your answer for part (c) into 1 + x + x^2 / 2 (the Taylor series of e^x to the first 3 terms)
ah so they factored out an e^1 = e
then they used this with x = -n/2 x^2 + ...
1 and two parts
So three?
Including e^1
My answer wouldtbe different if i did my approach no?
Btw
no, the other part is $-\frac{n}{2} x^2 + \frac{n(3n + 2)}{24} x^4$
Because i would have 1+ (.....)
south
the person who wrote this solution is being really clever
that's an unreasonably short solution
what's your approach again?
U=
So write e^u =mclaurin series
Then sub my expression of sech^n(x) into u
Of the mclaurin series
Tbf mabye I aint quicker bc of some expansion
Yh thanks, its some tough question lmao
yeah, so if you try to sub in the entire thing, (1 - n/2 x^2 + ...) into 1 + x + x^2 / 2
it would be very painful
The question as. Whole was tough
STEP is tough in general ngl
ah it's Edexcel mb
interesting
Because u won't actually expand the
U would pick and choose
Ifyk what i mean
of course you would
Wana sre another tough question i struggled on?
it's just the x^2 / 2 that becomes a bit more tricky, figuring out which terms to include
no thanks
I mean you can still post it for others
I'm just saying don't expect me to help you on it
Nah i dont need help
It was jsut for u to attempt it
Found it a cool question
Even this q was pretty tough it had me smiling abit even tho i couldn't do it
Close.
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little bit confused by part ii
is it just asking me to sketch all the induced subgraphs of G that have 4 vertices?
or all the isomorphic graphs that are isomorphic to one induced subgraph of G?
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How do I solve this improper integral?
you already closed the other one
Yea but it’s still named me
it just takes a bit for closed channels to be recycled, don't worry about it
anyway for this question you can do a substitution
U = cos2t?
i don't think that would help in this instance
that should work
Can’t I take the integral of cos2t
Isn’t it like sin(2t) over 2
Or something
well if you know the antiderivative already then sure
if you didn't know the antiderivative then you could substitute to get one
What would I put in for like
My bound stuff like uhhh
1/2(sin2t) when t goes to negative infinity
What happens then
Is it just divergent because it oscillates
Between -1 to 1
it doesn't approach any one number, that's true
So it diverges right because of that
yes, if the limit doesn't exist then it diverges
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Nothing.
For problem 30
Would the correct approach be to start with integration by parts
u = lnx
dv = 1/x^2
no
You can actually just u-sub this one
substitution
u=ln(x) works fine, since x=e^u and you already have a 1/x term for the 1/xdx
How would u = lnx work wouldn’t I have a 1/x left over
If you want to, sure, but the faster method is definietely subsitution
Hence why I said x=e^u
Oh
Then it just becomes standard
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Is my setup for problem 41 correct
Yes
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wtf
i got r = 3
so i plugged in x = -3 and x = 3 into the series
so the 3^n cancelled
which left n -> inf of n
which is infinity
$\sum_{n=1}^{\infty}n$ is divergent
;(
As well as $\sum_{n=1}^{\infty}n(-1)^n$
in any case, how could the interval of convergence possibly be (infinity, infinity)
;(
as soon as you know R=3, you know the interval is either [-3,3] or (-3,3] or [-3,3) or (-3,3), those are the only possibilities
Did you just take the limit of the sequence without considering what the actual convergence is
yeah
cause i saw in a video
they got R and plugged in -1 and 1
into the series
then took the absolute limit
Yeah you're supposed to actually consider convergence
^
wait so u dont need to plug values back in?
you always need to check the endpoints
You need to, but don't do what you did
i.e. check the value x = R and x = -R
You need endpoint to see whether the series converges at the endpoints
because they may or may not be included in the interval of convergence
wait so did i do the endpoint checking wrong?
did you find that the series converges or diverges when x = 3?
diverge
diverge as well
yep
they were both infinity
so what is the conclusion?
oh so that means the endpoints arent included
right
well if you got a finite limit at all
oh so it doesnt have to be 3 or -3
nope, convergence just means the series has a finite limit
yep
so you put the [] instead of ()
yeah
and mixed form if one is included and the other is not
(all four possibilities can happen, depending on the series)
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yw
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does anyone know how to do this?
did you try anything yet?
do you understand what the question is asking?
sometimes if the equation is like y=x+8, why do u graph only parts of the graph like a ray instead of a line? im confused about that😭
like idk when to graph the equation as it is or just parts of it
t can be any real number for this question tho
that restriction is for the others
<@&268886789983436800> spam
what question are you talking about
#8 parametrics
how do I know which direction it’s going in tho
idk what the t= (number) labeled on the graph is about 😭
this is what I did so far
yes that looks right
is that it?
cuz I thought I needed to graoh the direction it’s going in and t values. how do I know where t=0 begins
sorry I just dont really understand parametrics
it doesn't matter where t=0 is
for x = t + 1, increasing x is the same as increasing t
im confused… wouldnt t=0 be at the point (0,1) cuz when u substitute t = 0 into both equations, x would be equal to 0 and y is 1
yes, but again t=0 does not matter
should probably fix that arrow pointing up
all your other arrows look right
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Can someone explain this to me
Expand the bracket
What is it equal to?
y^4 +2y^2 +1
Yep
And what does (y^2+1)^2 expansion look like
I see
How do you know that compresses into that though
Is there a formula
Cause I don’t remember
if we set y^2 = a, and b = 1, then this reduces to a^2 + 2ab + b^2
so that's why
Ok thx
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Hey guys i have a question
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
i am trying to figure out how to solve this exercise it says i need to give the integral of the following areas and like how am i supposed to do that without being given a function?
Notice how each of the definite integrals have bounds that perfectly conform to the endpoints of given regions.
You don't need to know the exact function, because you are given the area of each region. And, by definition, a definite integral is simply the area under the curve.
@reef marten Has your question been resolved?
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do i like ask here to get help
Hello there fellas,
Guys I’m searching for a group of students auditing the course of Introduction of Mathematical Thinking by Stanford and Coursera. How can i find such a community online? Thanks in advance
ok well can someone help me w graphing piece wise functions, i’ve watched several videos and examples, i cannot understand it for the life of me
what’s confusing
literally like all of it, i don’t see how i am supposed to graph this
do you have an example
do you know how to graph -x - 7 and x - 5 normally
like the y-int is -7, then i go down one and right one?
yea
so if it makes it easier you can think about drawing these pieces individually like you would normally but then "erasing" the bits that are outside of the region you’re asked to plot them in
so here you would for example draw -x - 7 but then erase everything that isn’t in the region
-6 <= x < -1
you’re taking a piece of the functions restricted to a particular region/domain
i’m sorry i re read that like 4 times i am still so confused
graph -x - 7
erase everything except where -6 <= x < -1
then graph x - 5
and erase everything except where -1 < x < 4
did i graph that correctly lmao
yep
but now get rid of everhthing except for the portion where x is between -6 and -1
i don’t really understand
but why? i though i had to have a line going on for infinity
so like that
nice
but can you make it an open circle at -1?
-1 isn’t part of our interval
it’s only -6 <= x < -1
click the dot or whatever
or -1
i’m about to cry i don’t know what im doing
this is good
so is that like it for the second one
or this
well the x - 5 but should only be for -1 < x < 4
not this
yeah i give up there’s no way for me to understand this, thanks for ur help 💕
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with 24, where does the 5 come from?
im confused over what value the problem is asking us to find
these are my teachers notes
They multiplied the top and bottom by 7.
As a result, the denominator became 7 - 2 = 5.
okay i got it sorry, i hadnt looked at one of the formulas i was supposed to use 😅
thanks!
.close
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.reopen
✅
im back im still confused
where does this come from?
damn me theres another formula
okay bye again
.close
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That's S, and it generally refers to the sum of the series.
If there is a subscript below S, like S_15, it refers to the sum of the terms up until n = 15.
okay
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"WHAT have you tried?" was not a yes/no question
oh
should i show my work
yep
yes
looks right. do you know how to turn a unit vector into one with length 7
idk
thast wherr i stuck[
would you be able to answer the question if your unit vector were just (1,0,0)
the questions says it has magnitude 7 but its 18
what ? its on x axis
yes
when you multiply a vector by a number like 5, what happens to its length?
can you find a vector on the x axis with length 7
increase
5(i+j+k)= 5i+5j+5k
not what im asking
so
(7,0,0)
the relationship between |5u| and |u| for any vector u is?
idk
when you multiply a vector by a number, its length is also multiplied by that number (or its modulus, rather).
the vector 5u always has 5 times the length of u
etc
this is something you should know
i have math exam on 2 june 3 chapters left vector,3d geometry,linear programming i want to finish it quick
ok but how is that relevant
this is something you were missing and have to know anyway
but of course we aren't forcing you
i started vectors today
if you want to ignore this knowledge that's up to you but please in that case explicitly tell me "i want to throw this away"
no i want to undersatnd vectord
ok right
then hold off on the whining about how many exams you have
when you multiply a vector by a number, its length is also multiplied by that number (or its modulus, rather).
symbolically, $|c\vec{v}| = |c|\cdot |\vec{v}|$
Ann
?
v is a vector, c is a number by which im multiplying it
ok
|these| denote length of a vector and also modulus of a number
do you understand now what i am saying
yes or no
i don't know how to respond to that. was that a question? a declaration? or what
What
Why
bc you confused me
and you also didn't give me a clear yes or a clear no
so i will have to leave now
💀
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take the derivative
yeah then uhhh find the zeros of the derivative
that should give you the time taken and you can reinput to get your value 🤔
oh have you studied derivatives?
you don't need them here actually: t = -b/(2a) works too
which one's a and which one is b
ah so it's for y = at^2 + bt + c
i've nver learned that
y = ax^2 + bx + c?
oh but you haven't learned the x = -b/(2a) part for the vertex right
well it comes from completing the square of y = ax^2 + bx + c
@atomic pulsar Has your question been resolved?
no but i havent learned "at^2 + bt + c"
it's the exact same as ax^2 + bx + c
it's just that instead of x you have t everywhere
oh
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i think im over thinking it
I understand everything minues the logic that determined the value of N
what is N supposed to represent?
so is it the smallest n that makes the inequality true?
i believe so
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i need help with (i)
idk where to get started
i tried (|a| - 1) - (5-a^2) >/= 10
(if a is not an integer)
and (|a| - 1) - (5-a^2) >/= 8
if a is an integer
@proper nimbus Has your question been resolved?
@proper nimbus Has your question been resolved?
@proper nimbus Has your question been resolved?
@proper nimbus I'm not sure what is being asked because I am unfamiliar with this short form of set notation
What does A = [5-a^2 , |a| - 1] mean?
I assume it is related to set builder notation, but there is something implicit going on here that I need explicitly explained in order to convert between the two
Closed interval
A range i think
Huh! I guess that would make a lot of sense.
Sorry, I was imagining stuff like set builder notation rather than a simple range.
That's quite silly of me

@proper nimbus What I would start with is recognizing that if your interval starts and ends with an integer then it contains end-start+1 integers in total.
So the range [3, 7] contains 7-3+1 = 5 integers in total, they are (3, 4, 5, 6, 7)
So you actually need (|a|-1) - (5 - a^2) + 1 >= 10
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hai
i come with this sol from the book just more elaborated with an exxample
my question is how to prove that for every boolean function f there is always fA s.t f=fA?
this is the proof in the book but only construction of A (what I did) appears
how to prove the last part (checking that indeed f=fA)
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isnt this supposed to be the other way around (less than or equal to)
no?
well the line is where they are equal
since 0 is not bigger or equal to 3
everything above the line will have the y value be bigger than the right side of the equation
hence ≥
Pick a point and check
that's why it's not shaded
yes 0,0 didnt satisfy
@cunning kettle they check the point (0,0) and find that it violates the inequality therefore the entire region it's in is not what we want
Which region are you describing though
so it's not shaded
so shade the other half
which is what they did
If you are describing blue, pick a point from blue
you dont need to do that
it's either above the line or below the line, pick any point and see if it's in the shaded region
if it's not then you shade the other half
Yeah ik they didn’t shade it, we are trying to determine the inequality
I’m confused why they did > and - sign in after y in the first line
you should type >= if ≥ is unavailable
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What's your doubt
Ben, Nico, Shaw, and five other classmates are sitting in a row. How many different way(s) is/are
there if no two of Ben, Nico, and Shaw sits next to each other?
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The Mirror Room Problem (2D)
Imagine a rectangular room with dimensions M×N, where M and N are positive integers. This room is placed on a 2D coordinate system. We are interested in specific points within this room:
Points of Interest: These are points that lie on the vertices or edges of the rectangle.
Integer Coordinates: These points must also have non-negative integer coordinates (e.g., (0,0), (1,0), (0,1), etc., up to (M,N)).
The walls of this rectangle act like mirrors. We can place laser emitters at any of these points of interest.
How the Lasers Work:
When a laser is fired, its beam travels in a straight line.
The path of the laser beam must always have a slope of either 1 or -1.
When a beam hits a mirrored wall (an edge of the rectangle), it reflects, continuing to travel with a slope of 1 or -1.
The Core Problem:
What's the formula to find the minimum number of lasers needed to hit all the points of interest in an M×N rectangular room?
The image below is the 4x3 example. For this example, 2 laser emitters are required.
instead of just having one rectangle, imagine the rectangles tile the plane
and then instead of the laser mirroring it goes into the next rectangle
that should probably help
I just rephrased the problem
I just realized that the answer was technically infinite before
I'm mostly looking for an alternative solution to the one I have already found.
Perhaps I should head to help forum instead?
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I have solved this question till here using the definition concept of Newton's formula. now I am not able to understand what to do after this
To find the required value
in the last line you should have T everywhere you put P
Yup I noticed it
$T_{n+3}-2T_{n+2} - T_n=0$
Ann
now you want to say something about T_11 - T_8
we are free to put any n we want
in this recurrence relation for the T's
Let n=8
Ann
do you see how to continue now?
Is the answer 2?
yea should be 2
work not shown, but the answer is indeed correct.
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T11-2T10 - T8 = 0
T11- T8/T10 = 2
you could have (and should have) said "sorry, i'll be back soon/later/idk when"
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How to proceed after this using Newton's formula
How to approach
Are you aware of the identity $a^n - b^n = (a - b)\left(\sum_{i = 0}^{n - 1} a^{i}\cdot b^{n - 1 - i} \right)$?
