#help-28
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(56,73) = a(1,1) + b (2,1)
a+2b = 56
a+ b = 73
solve for a and b
is that right @nova basin
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Sorry for the stupid question but what do I need to calculate the a values since I only use x and b? (RSA algorithm, variation of the Euler function)
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2x^3-7x^2+10x-2
how many terms are there
terms?
4?
are u sure?
Yea just count the terms in equation
1 is 2X^3 , 2nd 7x^2 , 3rd 10x and 4th constant thats 2
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For this
I’m trying to fill in the hessian matrix and don’t know what f31,32,33 would be ?
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3/1 x 4 + 5/4 x 9 + 7/9 x 16 +..... + 19/81 x 100
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Pls help.
10 testers can complete 50 test cases in 40 days. All testers are equally productive. A project team has 40 testers available for 10 days.
How many test cases can they complete?
compute how much one tester does in one day
then extrapolate from that for the second part
I found 1 tester did 1.125 in one day. Is it correct?
Can't find second part
no
if this were true 10 testers would do 10+ in a Day, and 50 in less than 5 days
1 tester did 5 tests in 4 days. Then in one day it's 5/4 = 1.25
I confused
Actually i divide all numbers to ten. But i don't know it's right or not and get 4
well its not correct, as you can see from my message explaining why its not right
think about a simpler version:
2 testers, 2 test cases, 2 days
each tester did one test cases in 2 days, think about why
or think about it like this you have a total of 10 people that can complete 50 tests in a total of 40 days, now you have a restriction of only 10 days but you also have 40 testers how many tests can 40 testers complete in the restriction of 10 days based on the original idea of 10 people that can complete 50 tests in a total of 40 days
basically the idea here is to find how many tests one tester can do in a single day and then go from there
Did you mean to divide tests by people?
To find 1 day
its more like (50/40) tests per day / 10 per person
In this case in 1 day 0.125
Oh(
tests / days * people
i think
beacuse its the amount of tests solved / how many people * days alotted
Yeah actually it can be
But then i need again for second part
nope
that solves for how many test on person can do per day
so u just then plug in and multiply for end resuly
Answer is 50?
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$f(7) = -7^2+9(7)$
its asking what is equal to f(7)
your missing the negative sign
which means you want whats on the other side of the equals sign
yes you are also missing the negative sign
so that will be the answer
Thank you
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Hello, just started studying and can't seem to understand where the answer i came across comes from
Can't figure out how
x = -1 or x = 7 comes from
you just solved the quadratic
use delta method
theres a lot of ways to solve it
factorize, complete the square, quadratic formula etc
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What went wrong
@unreal hull Has your question been resolved?
<@&286206848099549185> would like some assistance
Take -32 feet per second ×5 seconds. Equals -160 from 500. Equals 340
no 💀
that's just respectfully wrong, + i already put in 340 as a desperate attempt
i wish all i had to do was plug in 5 😭
Oh, sorry
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i'm pretty lost on this question, would someone be able to help me?
@fickle gale Has your question been resolved?
<@&286206848099549185>
@fickle gale Has your question been resolved?
@fickle gale Has your question been resolved?
Maybe draw a big circle and a small circle
and a chord of the same length in each one
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Can anyone explain the underline?
You are just replacing n with x
when x >= 1 log(1) >= 0 so you can drop that term, similarly x^2 > =1 when x>= 1 so you can drop that term too
Sorry I don’t get it
if log(x)>=0
If we take away logx isn’t that gonna decrease the values
There is a negative sign infront of the log(x)
You have a positive number (1-alpha)x^2. Suppose it is 7 for the sake of illustration, and you have log(x) >= 0, suppose it is 3, also just for illustration
Yeah I would understand if it’s (1-a)x^2 - logx <= (1-a)x^2
Yeah then u have 7 - 3 >= 7?
Yeah okay, there might be something wrong there
Hm also how does that show this one the first place
if (1-alpha)n^2 - logn >0
isn’t that supposed to be a less than
I suspect the problem is that the series you were supposed to be studying is supposed to be n^2 + log(n), not -log(n)
I don't see an obvious way to recover this strategy with that error
I checked on wolframalpja and apparently because alpha is less than 1
The inequality holds
Otherwise it fails but I don’t see why that is the case
Well, for starters, (1-alpha)n^2 is positive
so you at least have that alphan^2 + (1-alpha)n^2 > alpha n^2
You are really then interested in whether or not (1-alpha)n^2 > log(n)
Usually in the context of this kind of problem, you don't really care what happens for small values of n, and you know that n^2/log(n) tends to infinity, so that inequality is "good enough"
But I don't see that inequality as immediately obvious from the little bit that was written down
I’m so confused rn
Why is for example 1.5x^2 - log(x) not greater than 1.5x^2 when x>1
But likes like 0.5x^2 - log(x) > 0.5x^2
No wait this makes sense
But this doesn’t t
Just to be clear, you are aware that this is supposed to be true for some alpha between 0 and 1
You don't need this to be true for every single alpha
Yeah but I don’t understand why it’s true
My logic is that because logx is positive
So taking away logx will decrease the value
so how does something positive - something else positive end up being more than the original thing
One way to look at it is that you only really need to establish (1-alpha)n^2 > log(n)
Note that n^2 is always larger than log(n) for n>0
and the gap gets larger as n increases
So you can always choose alpha closer to 0 to make the gap between (1-alpha)n^2 and log(n) larger
Why is alpha being close to 0 making the gap larger?
Oh yeah
Makes sense
I still don’t get the inequality y
Honestly, that argument is really more thinking than I usually do for this kind of problem
You have an infinite series, whether you start at n = 1 or n = 100000 it doesn't really matter. A finite sum of finite numbers is finite
So you have that (1-alpha)n^2 > log(n) in a way that is "good enough" to test the convergence, because if that inequality isn't true, just start your index at an even larger number until it is true
and you know that such a number exists because the limit of n^2/log(n) goes to infinity as n gets large
Worrying about the specifics of an alpha that satisfies this is really irrelevant
Hm okay yeah that makes sense
Okay
But hold on I think I might see a way to show it
That inequality is the same as showing
x^2 - (1-a)logx> 1
Right
Oh no it’s not
damn it
it’s x^2 - logx /(1-a) > 1
Which is not really obv
I really do insist that this problem makes a lot more sense if it was just a +log and not a -log
You can see that with the - sign, you have a lot more to worry about than what is written, and if it were a +, no further details are required anywhere
@ivory moon Has your question been resolved?
Yeah Hm
Thanks I’ll try opening another channel just to see if someone can make sense of the inequality
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✅
@peak drift
$Pure$
faq
lol that’s weird
$Pure2$
are u p series...
Bro what
ok
Faq
No I don’t see it
@ivory moon Has your question been resolved?
lol
Do you see it my student
$Pure$
i do
Go on then
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Just to preface, this is not a test. It’s an open book assignment that is meant for practice, cooperation and asking people is 100% allowed.
Is that correct or am i doing something stupid
I feel like there shouldnt be a variable on the bottom
Grade 12 calc btw
,rccw
No, that's right
Wonderful, thank you
you should take a look at how you expanded the denominator though
O what did i do wrong
do you know about the FOIL method?
ah
so the thing is that you can't just square the first term and the last term
here's an example
Oh i missed the middle term lol
yeah
So its wrong
in your case it would be (2x+5)(2x+5)
just the denominator
you applied the quotient rule correctly, just didn't expand (2x+5)^2 properly
So its 4x^2 +20x + 25
yes!
So deriv is 17/that
yup
Thank you
I just asked she said it doesnt matter

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Can someone explain why he doesn’t do +2pi n
functions bounded from 0 to 2pi
But for number two he does do that
wdym where does he put +2 * pi * n in q2?
oh do u mean why he puts pi n in q1 and 2 pi n in q2?
Yea
or like why the answer doesnt actually have either?
The first one why he put 2 pi in question two and pi in q1
This was the first question
Basically the teacher told us to solve for increasing and decreasing for both of them
And not just find the critical values
did u delete the message with the other one that was + 2 pi n?
the reason its + pi n here is because its sin(2x) and cos(2x). the period of sin and cos is pi, so the solutions recur every pi/2 instead of pi
Ok but in the other one it’s cos(2x) also
But there isn’t a sin(2x)
And the question is in the picture the one with 2 pi n
@lilac pagoda
wait where
can u reply to the message
I dont see the image anymore
because its not sin(2x) = 0
its a specific point
which aren't at regular intervals of pi
Can you explain that a little more
Ok
so he did + pi/2 n
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,tex \int \frac{3}{1 + x²} dx
Nalla Manithan
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
is the answer
Take out the 3
And it’s a common trig integration
,tex 3 log |1+ x²|
Nalla Manithan
I know
,w compute d/dx(arctan(x))
Okay
That’s completely wrong
Very wrong
,w d/dx( 3 log( abs(1 + x^2)))
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whats the difference in doing svd for full matrix and the rank format
could you elaborate on what you mean?
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help please
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hello

Subtraction of 4-digit and 5-digit numbers with borrowing (decomposing)
Ty for vid I forgot what to do when the top number is bigger
so i go 8-5 = 4
I cant do 5-9
So I take away 1 from the 6 and its 15-9?
Right but 8-5 = 3
how old are you?
24
ty
i know its like 5th grade math I just forget the steps/order, just need to do a few to refresh my memory
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Can anyone help differentiate this:
$\QuotientRule$
Modus
help
I know I'm aksing what you're struggling with
I mean, you don't understand the formula or you can't differentiate x^2 + 2x - 1 or x + 3?
I was wondering how to differentiate but i think i understand now, Ill get back to you when i finish
I forgot
Lol
$\PowerRule$
Modus
@lost jackal Has your question been resolved?
@lost jackal Has your question been resolved?
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How do I do D?
When do your criticial points occur?
0, pi/2, pi, 3pi/2 and 2pi tho
and how can you determine which are mins or maxes?
Well in this case there’s no phase shift so it doesn’t matter at what height the min max occurs because it still happens at the same time as regular y = cosx does
You can just look at it graphically
can I get help with part D tho
like
idk I’m not making any progress lol
They are asking for the times at which h is minimum
f(t)= 12cost +15
Find t at which function is minimum
-1<=cos t<=1
You'll get minimum value of f(t) when cos t = -1 yea?
yes
How would I write this as an answer tho
Am I solving for cos(t) = -1?
Yeah
Nice
But I’m not given a domain restriction so
I guess I’ll just write the first few solutions
Since there’s multiple
Because cos = -1 only at odd multiples
Thats why 2n+1
And not n
Cuz n would give both even and odd
oh okay
Thanks for the help
By the way
For part a) is this the same thing basically?
Yes
if so do I use like -1<=cos(2pi•t/3) <=1
Yes
Yea they are basically asking when the function is max or min so you just have to get where the function is max and where it's min
Crocodile bro this your home in the pic?
nah
Part a is the same type of problem right
but in the solution they don’t solve the trig equation
They let cos(4pi•t/25) = 1 or -1
And then plug that into 1.3-0.6(1) or 1.3-0.6(-1)
You dont "let" that, it's just a fact that cos lies -1 to 1
Ohh
So if it asks when the max or something occurs then you solve the equation but if it just asks the height at max and min you can plug it in
Yep
-1 and 1
hm okay
so say I had
f(x) = 1 + 3cos(pi/3•x) + 9
And I wanted to find the max and minimum
I can do
1 + 3(1) + 9 = max
1 + 3(-1) + 9 = min?
Okay
Well since it’s reflected across x axis then
5 -3(-1) is a max
And 5 -3(1) is a min
Nice
I have something to say tho
Don't try to "learn" the way to do that question
Remember the basic idea i told you
Value of cos can be anything form -1 to +1 so you use basic logic what value from -1 to +1 do you need to put. To make the function maximum or minimum
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AB is 8, AC is 12 and ST is 5. if SB is twice the length of AT, how will i get:
a. length of AT
b. length of BC
i know similarity theorems but i dont know how to apply it
How do you even know that triangles are similar?
I don't think this is the place to ask this. Try #chill #discussion.
I need help on something
!occupied
Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #❓how-to-get-help for instructions).
oops sorry forgot to mention that its given that st is parallel to bc
Ah. well, then just close your eyes and apply similarity stuff.
uhm
as/ab = at/ac so as/at = 2/3
i apply same logic with sb/tc = 2/3
i dont know how to go from there
Here you found as = 2/3 at. Pretty sure you can use that somewhere.
You have some implicit equations as well. Just look at the figure closely.
ohhhhh
im so dum
since as = 2/3 at and sb = 2at, as/sb = 1/3 right?
which gives as = 2 and sb = 6, so at = 3
so ratio as/ab = 1/4
which makes ab = 4ST = 20
am i right
Yes
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hi i was wondering if anyone cud give me a hint for this assignment question?
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plug in x values that are close to 0 into the function and fill out the table
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ik i have to use lhopitals rule but im not sure how to make it into inf/inf or 0/0
how about, set y = function. Then take log of it
try taking $e^{\ln(\cdots)}$ of the whole thing then you can use exponent law for log
Soosh
yeah
so you can take the limit into the power
also note that 10/x comes down
by log rules
what does this mean
$e^{\lim{\frac{10}{x}}\ln(e^x+2x)}$
where did the ln go
WhoTao
oh ok
whenever you have a function with the indeterminate form $1^{\infty}$ you should most of the time take $e^{\ln(x)}$ becuase that is how you get the $\frac{0}{0}$ indeterminate form which is easier to work with:\
$$1^{\infty}=e^{\infty\cdot\ln(1)}=e^{\frac{1}{0}\cdot0}=e^{\frac{0}{0}}$$
PajamaMamaLlama
note that that final part has some very cursed calculations but we're taking limits so it's fine but I just didn't bother writing them
so when we get that 0/0 finally, we can very simply apply lhopitals :)
and also don't forget because $e^{x}$ is a continuous function in $\mathbb{R}$ we can say $\lim_{x\to c}e^{f(x)}=e^{\lim_{x\to c}f(x)}$
PajamaMamaLlama
I also think so 
btw you only need to take e^ln(x) of one side
because e and ln cancel
oh
so you have $y=e^{\lim_{x\to0}\frac{10\ln(e^x+2x)}{x}}$ how would you proceed?
PajamaMamaLlama
ahh you know how to do that one, yes? :)
take the derivative of the top and bottom of fraction and then do the limit

hope I taught you something
thank you for taking the time to learn and listen much appreciated as well
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did i do this correctly
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can someone tell me how to get the matrix multiplied to A?
I know it had something to do with the steps of the RREF process done to A
but I can't remember how exactly
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You're kind of going backwards in a way and assuming what you need to prove
$g \circ f$ being injective implies that whenever $(g\circ f)(x_1) = (g\circ f)(x_2)$, then $x_1 = x_2$
@devout valley
You're given that g compose f is injective, and you have to figure whether f must be injective
i.e. for f as is, you want to show that this must be true (or otherwise provide a counterexample where it isn't!)
Yep and also this isn't necessarily true (you don't know whether g is injective by itself either!)
Basically if you have that anywhere, you must have x=y
since g(f(x))=g(f(y)) is injective I cannot say f(x)=f(y)? I can only say x=y?
Correct 
(in fact there are counterexamples where g needn't be injective in general but the composition g circ f is)
Remember: this is what you want to show to be true!
I feel like its just a definition i forgot to memorize...
i miss when math was just numbers
Awww
takes a while to get used to
Anyways, let's try to prove this then
We know that $g \circ f$ is injective, so whenever we see anything like $(g \circ f)(x) = (g \circ f)(y)$, we're immediately allowed to say that $x=y$
@devout valley
But we want to figure out whether $f$ is injective, so let's assume we start off with $f(x) = f(y)$, do you have any ideas of what you can do with that?
@devout valley
i know f is function
A -> B
uhhh
thats it lol
also g : B -> C
also an injective function means the definition mentioned earlier
also the converse is true
interesting
This is the contrapositive: an implication is equivalent to its contrapositive
The contrapositive of "if A, then B" is "if not B, then not A", whereas the converse of "if A, then B" is "if B, then A"
The converse does happen to be always true, by definition of a function of course
interesting...
if we were able to see something like this, our job would be done, right?
am i supposed to have an epiphany
i thought we already set the gof x = gof y to x = y
since gof is injective
That is a true statement, but...
We want to show that f(x) = f(y) leads us to x=y somehow
aight so we got x = y
There needs to be a set of valid steps that allow us to say that x=y
This is where we start, that's all we can really assume so far
Yep 
perfect!
It is!
You start off with $f(x) = f(y)$, then you can then conclude that $g(f(x)) = g(f(y))$, but as $g\circ f$ is injective, that gives $x=y$ as we need
@devout valley
As per...
...here
Oh so thats just a theorem I should memorize
Replace [blank] with whatever the function you're thinking of, whether that be g, f, g circ f, etc etc
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Translation: m element of p exactly when m divides n
either proove or disprove that the relation, if given as a subset of the cartesian product is a function
well what do you have to check for something to be a function
i only know the german words but lefftotality and injectivity
its "rechtseindeutig" in german
no no
but ok
i confused it with injective
whatever
is it univalent ?
ok
and I have to go, sry
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@dense nimbus Has your question been resolved?
Yes this is a function I believe. It is the function that takes an integer and returns the set of its divisors.
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To find the angle of intersection, i first have to determine the possible point(s) of intersection, but how do i do that?
Think ive found it, just put these 2 in a system of equations and solve
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hey
is it legal to prove something by proving that the opposite of it is wrong?
i have to prove that thisis normed spacebtw
What axiom are you disproving exactly?
i want to prove that |x+v1| + |y+v2| <=|x|+|y|+|v1|+|v2| by disproving |x+v1| + |y+v2| >|x|+|y|+|v1|+|v2|
In general, yes. If you are trying to prove statement A, and you can show assumption of NOT A leads to a contradiction (ie. NOT A is false), then you know A must be truthful.
If you could show assuming $|x+v1| + |y+v2| >|x|+|y|+|v1|+|v2|$ leads to a contradiction, then this should allow you to conclude $|x+v1| + |y+v2| \leq |x|+|y|+|v1|+|v2|$ is correct (I believe)
pencentre
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I know that ab=-3, but what should I do next?
$(a-b)^2=a^2-2ab+b^2=\textcolor{red}{a^2+b^2}-2\textcolor{blue}{ab}$
PajamaMamaLlama
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i need help
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how can i find every combination of elements in a set X, that sum to an integer N?
For example, X = {1, 2}. N = 4.
Solution set =
{1, 1, 1, 1}
{1, 1, 2}
{1, 2, 1}
{2, 1, 1}
{2, 2}
i think this would be a combinatorics problem
Do you want an algorithm to enumerate every single combination?
yeah
i guess this is more of a programming problem than a combinatorics problem then?
Probably yeah
You can make it recursively
We'll say N=10 and X={1,2,3}
First return every set that works that starts with 1
Then return every set that works that starts with 2
Then return every set that works that starts with 3
To return every set that works that starts with 1, first return every one that starts with 1,1
Then every one that starts with 1,2
Then every one that starts with 1,3
So you'd get like
1,1,1,1,1,1,1,1,1,1
1,1,1,1,1,1,1,1,2
1,1,1,1,1,1,1,2,1
1,1,1,1,1,1,1,3
1,1,1,1,1,1,2,1,1
1,1,1,1,1,1,2,2
1,1,1,1,1,1,3,1
...
basically listing them in lexicographic order
i mean i would do it manually
like, you didn't say you need it for large Ns
For example, X = {2, 3, 4}. N = 14
manually look for sorted solutions
4 4 4 2
4 4 3 3
4 4 2 2 2
4 3 3 2 2
4 2 2 2 2 2
3 3 2 2 2 2
2 2 2 2 2 2 2
then permute each
@grizzled lion Has your question been resolved?
if it's not a long story, why you need that
i was trying to solve this programming problem, i rewrote the problem into what i posted here, and i figured it could be solved with pure maths.
i don't think so
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ty guys
i think the wizard describes the same i algorithm i would use, it was hard to recognize
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im very confused by how this triangle is described
same
so it's an equilateral triangle, so all side lengths will be some same number, and then the diagonal length is 2 feet which i think is the thickness?
i get diameter of a triangle, but diagonal?
yea
let me send a picture of what i think it is
like this
and the 2 is the length between the triangle faces
idk though
thats a weird window
i need more context to guess
if it's 2 dimensional, the total force is 0
it just gets pushed equally from both sides
i get what you say, just why would that be called diagonal length
right, water is on one side
i went crazy there
it's 2 dimensional
like this is not about buoyant force
it's just a question of what they mean by diagonal, is ithe side or the height
the side makes more sense, vertices on both ends
which comes from the water being X deep at point Y
force is mass times acceleration
mass is volume times density
so how do i figure it out without a volume
and windows have volume
im confused by that as well
solution from google
hm okay, so i guess diagonal length would be the sides then
for the triangle
if it's just a 2d shape
im still just confused by the question asking for a slice
ive never heard of that outside of the context of a 3d shape
and finding volume
yeah it's being weird
so the triangle would be the same idea but i need to use proportions to account for the changing slice size
its an average density of water
@civic beacon Has your question been resolved?
u wouldnt happen to have found the answer to the second one
no it has the question but not the solution
how does this look
478 pounds is the answer
but depth of 5 is the lowest force, and it grows from there
we're accumulating the force at different distances and different cross section lengths
that's why there is a variable in both those parts of the integral
yeah, and the depth is at least 5, and more than 5 at every other point
how more than 5?
so im actually confused because i thought it should be the entire distance from the surface of the water
but your answer only does the length of the shape minus h
what it looks like on your picture is also what i picture
i don;t know why they did 4 − y
in my mind it should be 5sqrt3 - h
so im not sure
but if thats the answer to 1 ill just follow what it did
sorry i don;t know this well
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@civic beacon Has your question been resolved?
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i am not sure how to approach this
Find y in terms of x then diff
you are given a striaht line equation in parametric form
you can just use parametric differentiation or find straight line equation in general form
and then perform implicit differentiation
k
i would suggest the latter
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3x3 cuber \learnt CFOP
@
Yes
<@&268886789983436800>
It is
Coool
I was meant to do helpers /:
@shy root why ur even asking this when u can calculate that using calculator
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Sure
what r u even talking about bro
Geometry?
do u have any question?
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Yeah please try not to do this again
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!status
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
2
i pointed out simple definitions of a function and surjective/injective but i keep on getting contradicted by saying if f is not injective then it must be many to one meaning its inverse is not a function as it will be one to many but it states f's inverse is a function
am i allowed to set rules with my function such as x cannot be equal to 0
or any other rule that will make the functions inverse many to one/one to one
That is an interesting problem. So if f is not injective, then the minimum example is f(0)=f(1)=0. But then how can f-1(0) be surjective and map to both 0 and 1?
@tranquil rivet, give me your class's definition of f-1.
$f^{-1}(y) = {x \in X : f(x) = y}$
luke1
Are you sure that's all your book says on it? I have one idea, but not sure if it's allowed given your current definition
$f^{-1} : Y \rightarrow \mathcal{P}(S)$ there also this one but idk if it even holds
luke1
since i used latex to note down the definition and it was said in a lecture
and the lecture board wasnt that cisible for me in that lecture
visible*
My only guess is A=B={0,1}, f(0)=f(1)=0. f-1(0)=0.
You just need to think of what to do with f-1(1) now.
Idk
the question says "A, B and f" does that mean I can add constraints on f? since we were just changing A, B but nothing on f
Only constraint on f is that it is not injective, so anything else is whatever you want it to be
See here's where I have concern with your definitions. A function is invertible if an only if it is bijective. So I'm feeling like you're using some non standard definition here.
we also use the term pre-images
if that helps
and we also proved in a lecture that a functions inverse will be a function if the function is bijective
<@&286206848099549185> Anyone else have an idea?
um what. if f is a function, then f^-1 only exists if f is one to one?
im confused about the original question
f^-1 cannot be well defined if f is not injective
ie. how do we choose what elements in A to "map back to"
its the f(x) = x^2 problem
f is many to one (ie. f(1)=f(-1))
so how do we define f^-1?
I think theres an error in the original question is what im hinting at
related to a forum post in this module
right. suppose that f(a1) = b1 and f(a2) = b1
so that f is not one to one
how do we define f-1(b1) ?
do we define it as a1? a2?
its unclear
oh wait
f-1 cannot map to both (otherwise it's not a function)
you can use whatever function f you'd like as long as it's not one to one
Let's say we take $f:\mathbb{R} \rightarrow \left{3\right}$ to be $f(x)=3$. We note that $f$ is not one to one since $f(1)=f(2)$ for example. How do you define $f^{-1}$?
pencentre
We can certainly create some function $g:\left{3\right} \rightarrow \mathbb{R}$ such that $g(3)=1$ for instance. But now this function is not surjective.
pencentre
So I feel like you always run into a contradiction with this
Ye
ya i agree with you its a funky problem that may not have an answer with the definitions that i use for my classes
(in fact, i prove to my students that in order for f^-1 to exist, f must be injective)
my lecturer is aware of this question and seems to have no problems with it
its a problem sheet so ill get the answers later
id be curious to know how he/she is thinking about the problem
one post about this question says
Would the following answer be correct?
Let A = {1, 2} , B = {3}, and f(x) = 3?
f(x) is NOT injective as f(1) = f(2). And we can make the inverse of f(x) surjective by constraining the range.
Ah, now you're thinking about the question in a way that makes sense to me. YES you can often create an inverse function by restricting the domain of A (we do this for inverse trig, for example). However, once we do this restriction, then you necessarily make f one to one so it still contradicts the original problem that was posed.
Basically, you restrict the domain of f in order to create f^-1, you cannot restrict the range of f^-1 (if that makes sense)
At least, this is not a technique I'm familiar with
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Hi
I've got a logic question about estimations
I had a question were it asked me to estimate the number of errors that will present themselves after a run time of 8 hours on a computer if a specific virus was active. I answered the question and got a decimal answer, should I truncate it because it has a remainder of 0.25?
that completely depends on the expected accuracy of the method used for the estimation, expectations of the context you are answering this question in, etc.