#help-13
1 messages · Page 167 of 1
Austan
so like
(x,y)
cuz you can add em to get like a two dimensional plane
I wouldn't write it like that, but I see what you mean. Say R2 instead
oh
all 2D vectors
right
(real 2D vectors)
Okay but what if I added another vector
what if it was
$\begin{bmatrix} 1 & 0 & 1\ 0 & 1 & 1 \end{bmatrix}$
Austan
what's the column space of that?
can we get anywhere new? is there any more linear combinations we can reach that we couldn't before?
well the vector in column 3 is linearly dependent on the first two columns
yup perfect
so no
we can't
the column space is unchanged if we ignore dependent columns
so when we row reduce a matrix and find its pivot columns
we find out what columns are dependent
we ignore these
and make our column space from the pivot columns
oh okay
$$A=\begin{bmatrix} 1 & 0 \ 0 & 1 \end{bmatrix}$$
$$B=\begin{bmatrix} 1 & 0 & 1 \ 0 & 1 & 1 \end{bmatrix}$$
$$C(A)=c_1 \cdot \begin{bmatrix} 1 \ 0 \end{bmatrix} + c_2 \cdot \begin{bmatrix} 0 \ 1 \end{bmatrix} = C(B)=\mathbb{R}^{2}$$
Because the pivot columns of $A$ and $B$ are the same.
Austan
yeah this makes a lot of sense
now if you understand column space, row space should come easy. It is the same idea but for the rows
if we want to know the row space of our matrix
all we have to do is make the rows columns
and find the column space of that
transpose
right
So are you feeling good about all of this?
so what would we do if the question asked us for the basis of the column space
do you know what a 'basis' is?
pretty good actually this has been an enlightening discussion
well i know it has two properties: linearly independent and they span the space
a basis of a space, is a set of linearly independent vectors, that span a space
yes
so for R2
a basis can be
<1,0>, <0,1>
right?
yeah
those are linearly independent
they span R2
so they form a basis for R2
how about
<5,1>, <0,8>
do those form a basis for R2?
id say they do
yes
actually there can be infinitely different choices of basis's for any given space. Usually we like to choose the simplest one possible
for R2 we would normally choose <1,0>, <0,1>
right
okay
so earlier we said that
the column space, is the space spanned by the linear combinations of your columns
if we want a basis for the column space
we want to find linear independent vectors, in our column space, whose linear combinations fill the space
you should have a good idea of where to find these
oh so in a test, i would probably be asked to tell them a basis or a few bases since there are infinitely many
yes they will 99% likely only ask you for one basis
ah okay
let me do a problem on bases and i'll be back
okay, I have to go for now, but my final hint to you is that there was a reason we found the pivot columns
you can DM me if you need more help but I wont get to it until later
because they are the basis?
not in REF no
but the columns in the original matrix, that are pivot columns in REF
yes
ah okay
alright thanks man i actually have another small question, do you want me to dm it to you?
.close
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Differentiate the right side and use FTC
,tex .FTC1
riemann
F' = f
Oh
Ok
How do you know that but are you an iitian
Ok thanks @dire geode
.close
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hey, im trying to prove that +mod3 is associative and having some trouble
binary operation on the group {0,1,2}
I end up with versions of this and I can't really get it to be the same on both sides but my book says otherwise, also checking it seems like it is associative
Any help?
you cant just divide by 3 like that
what specifically do you want to prove
- or *?
Yea I was a bit confused because I technically need to take the remainder so I am not really sure how to approach this
ok you'd rather do ([a]+[b])+[c] ≡ ([a+b])+[c] ≡ [a+b]+[c] ≡ [a+b+c] ≡ [a]+[b+c] ≡ [a]+([b+c]) ≡ [a]+([b]+[c])
you usually never specifically apply mod n or division by n in the modulo set for n
not sure I really understand this
I presume you're familiar with the notation [x] in a Residue Class Ring
I am not 😅
e.g. in the Ring Z/5Z: [0] ≡ [5] ≡ [10] ≡ [15] ≡ ...
let me adjust that for the above proof as well
@grizzled scarab if you just take this general notation the proofs of the properties of the Ring become simpler
Idk what you mean by ring, I'd try to read English is not my native as well
But I probably can't use that in my course since I didn't learn it
what's your native, possible they match
I speak Hebrew
kk nvm
Is there another way to prove this? Kinda in the way I did it that makes sense at all?
it's objectively better as it also circumvents you having to define what a,b,c are in your proof
are a,b,c elements of the set {0,1,2} for your proof?
I mean if you work with modulo operations you'd usually also at least have to be able to use equivalence classes
which are denoted by [x]
therefore I'm not sure what you're allowed to use
you need to be able to somehow intertwine addition and the modulo operation, which you'd do via equivalence classes
@grizzled scarab like could you provide what operations and properties you've already learnt / area allowed to use
Pretty much nothing, it's like first course of uni and this is the beginning but this course assume no previous background
the approach of rewriting a modulo addition as an addition and integer division seems rather sloppy
I'll have to look into the stuff you said and ask my teacher
I appreciate the info
If you have been introduced to modulo, you also at least need to know equivalence, otherwise you can't calculate :D
since within Z/3Z, the number 0 suddenly is equivalent to 3
as well as to 6, 9, etc.
so you need to define this behavior as equivalence
and then you end up with equivalence classes @grizzled scarab
{0,3,6,9,12,15,...}
{1,4,7,10,13,...}
{2,5,8,11,14,...}
all numbers within these sets are equivalent to each other within Z/3Z
Yea they didn't really do that I guess, just said you divide and take remaineder = modulo
If I understand what you mean
yeah but once you actually want to prove anything, you can't apply the numeric method to the proof
with your half addition symbol
I think I have to ask my teacher for clarification
this part here is clear right?
k, because then the only missing step is
that you want to summarize these equivalence classes with a notation
because 0 would have the same meaning as 3 etc.
which is where the notation [n] comes in
so [0] stands for the equivalence class of 0
Ah I think I understand you now
when you write [0]+[1]
you don't "add" sets together, but you add equivalence classes
[0]+[1] = [1]
[2]+[2]=[4]=[1]
I'll read about it some more and look for more examples too regardless
Yea I think it's kinda what I meant here
kk, I'll again refer to the initial proof I provided, because that's how you'd prove it almost always
most definitely not with translating division and taking the remainder using symbols
Thanks again for all the info!
np, the main reason it's easier is that you can combine brackets:
[2]+[2] = [2+2] = [4] = [1] (within Z/3Z)
so yeah, I'd just write down this proof, you'll quickly grasp it
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with this
this channel is going to close soon because you deleted the original message
you need to open a new channel for your questio
!help
Please read #❓how-to-get-help
how do I add images because I need to upload the math problem
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$\frac{dy}{dx}=\frac{sin^3x}{tan^2y}$
Please don't occupy multiple help channels.
Xiyyr
(differential equation)
It's separable
Multiply by tan ^2y to the LHS and move the dx to the RHS and integrate
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what does « determine the roots unity » mean?
Determine values of x for which x^n = 1
isn't that the question lol
ik that one just not sure what my teacher means 😭😭
might have missed out an "of" probably a typo
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With what
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Can I get help with Statcrunch statistics software?
fyi, there is a #computing-software channel in case you don't get any luck here
(i don't know the software myself)
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I need help with this question
!status
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1. I don't know where to begin
2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
4. I got an answer and would like my work checked
5. I have a question about someone else's worked solution
6. None of the above
@spare narwhal
2
show current progress
Wym
your 7's should have a stroke through them, and your 5's should not be looking like S's
How should I write a 5 then
Okay
once you fix all this:
solve for x from the equation 3x+c = 5x - 13/2, and solve for y from the equation 3y + c = 5y - 7.
both x and y will be expressed in terms of c.
the leftmost 5 and 7 look the best
I've always written my 5's like the other way so this is a change
Okay
well it won't do for math because you don't want to ever confuse two different symbols for one another
and those fives are VERY misreadable as S. and vice versa.
mistakes like that are very hard to track down later lol
ok yeah good now do it for y
@tropic oxide
??
ok yeah that's correct
now calculate x-y and choose the right answer option based on that
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yeah checks out
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I want to understand this formula
I guess it is dot product of two vectors
a,b,c are normal vectors and x-x1,y-y1,z-z1 are plane vectors
you guess?
yes
$$x-x_1$$ looks like $$\Delta x$$ to me
One person
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✅
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How to find the equation of a plane which passes through middle point (3,-2,1)(1,4,-3)
You mean middle point of those two points?
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Can someone explain integration of area under graph
for negative area questions?
Do I just add a negative sign in front of the whole equation?
Example question?
yeah
I don't think you have to
But that part is negative area sir
I will have to put a negative sign in front of the equation
mmmmm kinda confusing question
Like if I integrate area within sin x
it could be either one because the area under the x axis would be considered negative in most cases. It never asked you to consider it not negative either
I cant set the lower and upper bound to be 0 and 2pi
wont that give me an area of 0
since the 2 symmetrical areas will cancel out
the area under the curve is zero
Shouldnt it be positive area
not unless you were asked to consider the area under the theta axis to be non-negative
Im confused now
So we always say that areas under the x-axis is negative areas
and minus them off the total area?
idk about always
but I learnt that if the area is under the x-axis it's negative
it should be negative unless the question says otherwise
Coz I had questions before
that showed a graph purely under the x-axis
and they asked to find the area bounded
the answer gave a positive number
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if i have integral(1/(-e^(-y))dy, whats the solution?
3cosy+coty=0 (solve for x)
if you mean $\int\frac{1}{-e^{-y}},dy$, you can simplify the fraction using the negative exponent
Desync
then it should be a recognisable integral
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$$ v_{pa} = v_{pb} + v_{ba}$$
One person
$$ 50 = v_{pb} + 50$$
One person
$$v_{pb} = 0$$
One person
The particle p relatiive b has a velocity of zero
so why does
(b) say the distance between the two is increasing?
huh
idk?
its just numbers
i assume that
is b is staionary
if a is staionary
then b is moving 50 km away
and p is moving 50 km away
no
no picture
nope
oh wait
picture i never seen
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A variant of Rod cutting problem, I know it's a Computer Science problem but it is also a Math problem and I want the mathematical approach for this question.
I have provided an image of the original question from the past ICPC problem, I have tried several things to find its best solution but I couldn't get to a valid solution, so I need someone who can help me understand this problem and find a solution.
the next three lines shows the result for each row
you can get to a maximum of 4 portions/pieces for the loaf of bread if the constant factor is 1.500000 (Float value in C++ which is up-to 6-to-7 decimal places)
@thin tusk Has your question been resolved?
I can try and find the largest possible cut by simple brute force and with a little trick
0.500000 / 1.5 = 1 / 3 = 0.333333 // upto 6-7 decimal places max
1.000000 - 0.333333 = 2 / 3 = 0.666667
0.6666667 > 0.4999995 // So this cut is not possible
// Now I aim for 0.666667
(2 / 3) / 1.5 = 4 / 9 = 0.444444
1 - 4 / 9 = 5 / 9 = 0.5555556
0.5555556 < 0.6666667 // Repeat this and you get to the largest possible cut.
// But it won't give me the optimal cut, but I can keep this approach going for a few more steps
// Now I aim for 0.5555556
(5 / 9) / 1.5 = 10 / 27 = 0.3703704
1 - (10 / 27) = 17 / 27 = 0.6296296
0.6296296 > 0.5555556 // This cut is not possible
// Now I aim for 0.6296296
(17 / 27) / 1.5 = 34 / 81 = 0.4197531
1 - 34 / 81 = 47 / 81 = 0.5802691
0.5802691 < 0.6296296 // Acceptable
// If I keep repeating it for n-steps I'll eventually get to the solution but it would take alot of operations which I don't want, it's not an optimal approach I want to find make sort of formula which would get me either the best first cut or the end state cut which in this case (k = 1.5) gives the result 0.214285.
// If a formula cannot be deviced then the next possible option is to find best cut with minimal operations.
@thin tusk Has your question been resolved?
@thin tusk Has your question been resolved?
<@&286206848099549185>
@thin tusk Has your question been resolved?
<@&268886789983436800> waiting for a long time, still haven't gotten a single response
i need to close this ticket
Many people on this server who can solve this were asleep when you asked, please be patient and only ping once.
Would a simple recursive process, where you cut the largest loaf such that you create a new smallest piece that is the (new largest piece)/k in size work? It's a greedy algorithm, so it might be suboptimal.
you can close it by typing .close
as it says in the instructions
please don't ping moderators about stuff like waiting for a long time
!volunteers
Helpers are just people volunteering their time to help you. Be polite.
IK how to close it but i havent gotten a single response
the problem is the cutting part
For instance, for k = 1.5
Loaf: 1.0
Let the size of the new loaf be n, Now we solve n = (1.0 - n)/k which gives n = 1.0/(k+1) or 0.4
Loaf: 0.6 0.4
We take the largest of these 0.6 and do the same trick, except we need to look at the 0.4 loaf or the 0.6 loaf depending on the size of the newest loaf, largest is better.
Looking at 0.4 we have n = 0.4/k = 0.2667
Looking at 0.6 we have n = (0.6 - n)/k => n = 0.6/(1+k) = 0.24
Because 0.2667 > 0.24 we take the former
Loaf: 0.3333 0.2667 0.4
Next, consider the two options for 0.4, which are 0.3333/1.5 = 0.2222 or 0.4/2.5 = 0.16, we find that 0.2222 is larger so we want to create that, however, doing so would create a loaf smaller than 0.2222 from the 0.4, so the best we can do is 0.2, which ends the iteration.
Loaf: 0.3333 0.2667 0.4
Given that a solution was provided that is better than this, a simple greedy algorithm seems like it cannot work.
the first cut is 0.571429 and 0.428571
Yes, I know. Please read all of the way through, it is not a solution, it is describing my attempt at a simple greedy solution that does not work
My guess is that the first cut is not unique, however
There are a range of values that will work.
And they are intentionally randomizing within this range to obscure the solution
Another attempt, let's find the smallest k such that you can make 3 loaves with any cuts.
If we make the first cut greedy to maximize the size difference between the two loaves, then we have
Loaf = 1/(k+1) k/(k+1)
Then we need a cut such that the larger loaf cut into half precisely is exactly equal to 1/(k(k+1)) which is k/(k+1) = 2/(k^2 + k), which implies k = sqrt(2)
So for k < sqrt(2) the best you can get is a single cut, for k >= sqrt(2) you can get at least 2 cuts (3 loaves).
And in the case where k exactly equals sqrt(2) this cut is unique. But for k = sqrt(2) + epsilon this cutting isn't unique, there is some "wiggle room".
I'll leave it to you to exactly determine how much wiggle room, it's just straightforward algebra. I'm going to move on to a minimal k for 3 cuts.
So for three cuts we don't want to leave as large a second loaf as possible, but as large of a third(!) loaf as possible, which means our first cut should be less greedy.
If we have loaves of sizes a, b, c after two cuts, we want the largest loaf (a) to get cut exactly in half and be exactly b/k in size (where b is the second largest loaf).
c will come from the first cut, and a and b will be determined from the second cut.
First cut:
Loaf: a+b c
Subject to the constraint that a+b > c, a+b < ck.
Second cut: a b c
Subject to the constraint that ak = c, equality required for optimality.
Finally third cut: a b c/2 c/2
Subject to the constraint that ck/2 = b <= ak, equality is required for optimality here as well.
Using a computer algebra system, it looks as if, ironically, you can get a solution for 3 cuts with k = sqrt(2) as well???
It feels like I've made a mistake somewhere but I cannot see it.
@thin tusk I don't know whether or not this helps you see an approach, but it looks like kind of a mean problem to reason about.
at least mathematically
There is probably some recursive solution that, while it does a lot of work, should be fast enough to run in a single second because computers are good at this sort of thing?
@thin tusk Has your question been resolved?
we are not sure how many total cuts we can make, so this assumption might not work
@thin tusk we're starting from the premise that we can only make 2 cuts, and trying to find the minimum k that will get us there.
I liked this approach
I did as well, unfortunately it is sub-optimal 😦
it didnt said I have to get that accurate result which was bothering me alot
i was thinking how they got to that result
those specific values which perfectly overlap with one another in smaller cuts
Loaf = 1/(k+1) plus k/(k+1)
How did you make this formula
that's not really a formula, but a description of the size of the pieces in the loaf at this step
the first piece is 1/(k+1), the second piece is k/(k+1)
should there be a + sign in b/w?
No, because it's not a formula
think of it as an array:
loaf = [1/(k+1), k/(k+1)]
ahh
Loaf = 1.0
k = 1.5
1/(k+1) = 1/2.5 = 0.4
k/(k+1) = 1.5/2.5 = 0.6
Loaf = 1/(k+1) + k/(k+1)
Loaf = 0.4 + 0.6 = 1.0
or [1.0] -> [0.4, 0.6]
that's what that part is saying
but unfortunately, 0.4, being the absolute smallest cut you can make, is actually too small to work with the 3rd cut
the problem itself is solved with this simple approach but there's still a big mystery
how they got to that precise numbers
I don't think that the problem is solved.
Because it's not optimal, and the problem specifies that you must cut the loaf into as many pieces as possible.
"indicating the maximal achievable"
and I think it probably fails in most cases.
because 1.5 doesn't seem like a special value
for 1.999, how many cuts can there be
lets assume the inputs are lower and upper bound
a whole hell of a lot
1.000 and 1.999
it's infinite for 2
and for 1 <= k < sqrt(2) it's only 1.
so there might be a finite answer
there is certainly a finite answer.
but my guess is that the value approaches infinite quite rapidly
the output size is limited as well
only 6 decimal places after decimal
so ig below 1 million max cuts
while your output is limited in precision, you could still in theory come up with a scenario where you output mostly 0.000000 and have more than 1 million entries, provided that you're keeping track of your numbers with enough internal precision
float will keep the result upto 6 decimal places for me so my answer wont search beyong 6-7 decimal places
a single precision float only does 6-7 decimal digits of precision, yeah. This is probably why they're saying not to output more than that.
also I got close to the actual result with my first cut
0.5849625 and 0.4150375
It looks, strangely enough, now that I've double checked, that sqrt(2) gets you both a second and a third cut.
k = sqrt(2) that is
i did log2(k)
I do not immediately see why that would be a good idea.
Can you share your thoughts?
i was messing around with random inputs and i thought maybe log has something to do with this problem and i tried different bases of log
like log base k, log 10 and log 2
which gave a close enough result to actual
yea when I cant find a pattern, I do some trial and error
so in other words, if you have a loaf = [a, b, c] with c the largest loaf, you try to make a cut such that [a, b, c (1 - log2(k)), c (log2(k))]? and if the smaller loaf is too small to satisfy the constraint you?
it has the same issue as your first approach
it might or most probably will fail at some point
since its not giving a precise cut as the test case
3/7
O_O
how in the what
can you make a table for values from 1.0 to 1.9
we can see a pattern emerge from it
also how is the first cut 25/61 for 1.6
k=1.5 cuts are 3/7, 2/7, 3/14
k=1.6 cuts are 25/61, 16/61, 25/122, 10/61, 8/61
I'm not solving this, I'm determining a simple rational fraction pattern given the decimal numbers.
these are all quite close, and all have related denominators, so I'm confident that there is some underlying pattern that they are exploiting.
why even 61, thats such an absurd number to pick
I do not know
surely if we dig deeper we can find their hidden pattern
If you have any other examples of valid output from the oracle function, it would be appreciated.
they only provided 2 test cases
So:
k=1.5
Loaf: [1]
Loaf: [4/7, 3/7]
Loaf: [2/7, 2/7, 3/7]
Loaf: [2/7, 2/7, 3/14, 3/14]
was the strategy
which seems more reasonable.
you make the initial cut, then cut each other in half.
k=1.6
Loaf: [1]
Loaf: [36/61, 25/61] (interesting that they're using perfect squares here)
Loaf: [20/61, 16/61, 25/61]
Loaf: [20/61, 16/61, 25/122, 25/122]
Loaf: [10/61, 10/61, 16/61, 25/122, 25/122]
Loaf: [10/61, 10/61, 8/61, 8/61, 25/122, 25/122]
perfect squares and a random prime as denominator (random to us for now)
with this pattern the next number should be
k: 1.7
49/85, 36/85
that doesn't seem to follow
adding consecutive perfect squares
well, there's no reason to assume that it's going to be linear (and every reason to assume it's not, as k=2 is literally infinite), and moreover the k = 1.5 case didn't feature consecutive perfect squares
maybe the jump is a little bigger b/w squares
ik the ICPC test questions have a really well constructed pattern, they always do
an old paper
nah i do my own homework
i dont want to look at the solution online, I would rather discuss it with someone else and approach the solution from scratch
they didnt cut 36/61 in half
instead they cut it into 20 and 16
I noticed.
it looks like historically ICPC problems at least from where I found, are numbered as problem A, not problem 1.
instead of writing 4/7 and 3/7
we can write it as
8/14 and 6/14
16/28 and 12/28
trying to make them a perfect square
Yes, but you'll be unable to make a perfect square, because you'd have to find a common factor such that you have 2^2 * 2^x 3^y = 2^2n 3^2m, and also 3 * 2^x 3^y = 2^2j 3^2k, this implies that 2n = 1 + x, but 2j = x, but both 1+x and x cannot be even.
@thin tusk before you go, a potentially useful observation
16, 20, 25 have common differences of 4 and then 5
36 and 25 the difference is 11
The algorithm might have the following structure:
why does it look like (a + b)^2
Well in that case the common difference in the numerator is just 1
I'm looking at the algorithm in two steps, first we try to divide the bins in a specific way, then cut them all in half
Then it terminates unable to do more
i have to take a deeper look into Strassen multiplication algo after this one is solved
F
@worldly chasm
1/(k+1) = 1/(1.6+1) = 1/2.6 = 5/13
take square of numerator and you get 25
hmmmm....
1/(1.5+1) = 1/2.5 = 2/5
take square of 2 u get 4
for k=1.7
i got 10/27 one half must be 100
is there a Pythagoras Theorem hidden in this
I don't think it's quite that simple.
So one thing you've missed is that in the 1.5 case, you're taking the square of 2 to get 4, but 4 is the larger of the two numbers.
in this case its 25 the lower bound
whereas in the 1.6 case, you're taking the square of 5 to get 25, but 25 is the smaller of the two numbers.
yea i noticed
I have been a victim of this so many times i lost count
well gn for now, i'll continue this struggle later today
good luck
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@tough fulcrum Has your question been resolved?
Hey! lemme take a look
you found the correct value of lambda (20/33) but you just made a typo when calculating y
so your answer is basically right, just a small arithmetic mistake at the end :)
Oh i see 🤦♂️
thanks for your help
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how am I not sophisticated enough to see why this x just vanishes bruh: I wanna set 2x ln(x) +x = 0 to find critical points | Actually just got a grasp on it while writing this question, is it because we can just find the 0 of the factor and that will do? Are there other ways to find the 0 too?
cuz then it's just $ln(x) = \frac{-1}{2}$ then $ e^{-0.5}$
Maggi
i mean x can be 0 and e^-0.5 if im not wrong
yea, it's just that 0 is not that useful when finding the absolute minimum
and that yea, 0 is not in the domain
therefore , as a product equals 0 iff one of the factors is 0 , x=0 is not an option
meaning the first factor has to be 0 , therefore you can drop x
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how do i solve this one?
is there a formula or something?
allowed to use calculator?
yeah
do you see the two R's
which make the arc
dont you see a triangle
that too isoceles
could you apply some trigono metric properties over here?
ok
try going over basic definitions of
them functions
oh yes how about we drop a line from ground to the plane
straight line
that'll make it easier to apply trig
ook
could you see how we are gonna apply trig
@unique isle Has your question been resolved?
You get r from this
Then use trigonometry by dropping an altitude from centre of plane to vertex
sin(0.5) ≈ 0.5
No wait that's radian
You're given degrees
sin(0.5°) = 0.008
And sin(0.25°) = 0.004
Use these to get answer
@unique isle
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How would I go about solving this without doing any actual "calculations"
@crimson sedge Has your question been resolved?
<@&286206848099549185> you don't have to read the question at all
Just asking
how I would get rid of the if statement
You cannot 😦
At least not without using functions that are essentially if statements
Like the indicator function or floor function or similar
One person
but still
Let u(x) be the function that gives 0 if x is negative and 1 of u(x) is positive (undefined at 0), u(x - Δx) will return 1 if plateau and 0 if ramp
And undefined if it lands on the corner
But I'm not sure what you're planning on using this information for?
Are you trying to come up with a general formula for b) and c) without using cases?
yes
Probably not worth it imo. Cases are cleaner and clearer.
The purpose of writing down math as math is to communicate the result with yourself and anyone else who reads it
The less that person needs to think to understand it, the better, imo
There's obviously a lower bound of thinking effort, but the expression itself shouldn't hinder understanding but facilitate it as much as possible.
What about making a statement like
wait nvm
literally exact same situation
I was gonna ask
How to answer True/False statement with math
I did this for a
Got kinda lazy
and didn't make variables for some things
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Can someone help me with this, I’m not sure how to proceed
It’s sqrt(log(-x))=log (|x|)
Now x<0 so sqrt(log(-x))=log(-x)
log(-x)=0 or 1
sqrt(x^2) is |x| not x
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How am i supposed to do this?
I guess i could plot the rectangle
Do i just reflect every point?
Yes, and then find overlap of original and reflected rectangle
i did something wrong
i guess it was just cuz i sketched wrong
looks like a straight forward question
should probs try again
okay yeah i got it
bad diagram lol
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How???
any chance the question is wrong?
it says log 2 = m
and than asks us to find log 25 in terms of x
does it mean in terms of m?
yes most likely it's just a typo
Yes it means in terms on m
But I still can’t do it
That’s why I asked this question, just to clarify
@glossy mango
when the base of the logarithm isnt specified, it's assumed to be log base 10 in most scenarios
log 10 is 1, obviously
smilarly, log 100 is 2
yea...
oooooooooo
so log 25 is 2(1-m)
np <3
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Just wondering if someone could see if its correct since i dont have the answers
if a = 2
and b = a - 14
b cannot be 4
Is this an exam?
its a past paper
i first got b from the 2a+ b = 8 so thats how i got 4
oh ok
so i definitely got something wrong somewhere
that says 2a + b = -8
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h mmmm
70/100 = 0.7
70/1000 = 0.07
70/10000 = 0.007
oho
so 70/9999999 must be very small
like basically
Your calculator is very peculiar
i learn statistaks, and it say fraction of choice if its below 0.05 then use certain formula
I think it's google formula
I mean calculatro lol
and fraction of choice is base sample divided by total possible sample size
Anyways e-6 Is basically 10^(-6)
ye
so i dont get why total number of surveyees in a theatre is theoretically infinite
its task where i dont know sample size
so i first need to deterimne n/N = fraction of choice translated
and textbook say
we can determine without calculating that its below 0.05 (which means we use special formula for below 0.05
because it is possible to survey infinite amout of people about what they think about theatre price
but humans are 8 billion
shiiiiiiiiiiii
so i calculate sample size is 70
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how would i do this?
you can fill in some of the missing angles, as they are opposite angles
as in, the angle where l and m meet is x degrees on both sides
so you can fill in one of the blanks at the bottom there
then, once you have all of them, do the replacements as given in the question (y=2w, v=110, etc.)
then they should add up to 360, which should give you something to work with
oh yeah and v = y + z= 110 right?
not sure why i didn't even think of even doing anything lol
yeah
can i also do w+z+x+y = 180
yes
okay thanks
answer should be 3/4 ig
i have another question
I'm just reviewing questions from a practice test
but the way i approached this iirc was
y is either in (-15, 15)
and the other one involves the (-20,10)
i guess i could combine it, but i don't have to right?
The answer is D? I don't really have an answer key so just ocnfirming
x=8, y=-16 satisfies those inequalities, but so does x=8, y=-14
so yeah, can be either way, so d
okay yeah i think it's trivial either ways, just confirming my answer
thanks
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Find Min
Min?
minium
are there constraints on x and y?
no
I thought there should be too, but realised it might just be about completing the squares
Try doing that
you've got an xy term so that will be fun for you
Does a minimum even exist?
just take the partial right?
Actually
of course
No nvm
i got an answer
Is dungx familiar with calc?
you sure you are not missing any part of the question?
Yeah can you show us the context?
no
oh
NOoooooooooooooooooo
Or does it just say "Find the minimum" and that's it
By calc we mean calculus just in case
its not english
Still, it would be better if you send an image
ok
Tìm giá trị nhỏ nhất của biểu thức:M=...
use translate
Giá trị nhỏ nhất đó đạt được khi x,y bằng bao nhiêu?
Find the minimum value of the expression: M=x(x + y) ) +y(y - 3) – 2x + 2010 What is the minimum value that is reached when x, y equals ?
math
Well, if the condition x=y is not given then there would be no minimum
wat
,w minimum of x(x+y)+y(y-3)-2x+2010
ahh
thats what i got when i used calc but how do you do it without calc
idk
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making a circular candy braclet, you have four letters to choose from: a,b,c, (with only three candies for each letter), if you can create braclets of length 1-4, how many possible bracelets can you make?
I said:
4 length = 3 * 3 * 3 * 2
3 length = 3 * 3 * 3
2 length = 3 * 3
1 lenght = 3
answer = 3 + 9 + 27 + 54 = 93
is this correct?
oh shoot i think thats wrong
because abc = bca =cab since its ciruclar
my next attempt:
length 1: 3
length 2: aa,ab,ac,bb,bc,cc = 6
im not sure how to do this recursively tho
idk what you mean
basically yea it follows real life
lol if it's circular then yes bca = bac
a real life bca bracelet is indistiguishable from bac
oh
yea
i agree
so how many bracelets can she make
using up to 4 beads
that are UNIQUE
Then abc ≠ acb
well in real life bracelets can be flipped
So then they can't be flipped
i don't know
just writing them down?
@crimson sedge Has your question been resolved?
<@&286206848099549185>
Burnside's Lemma may be helpful for resolving issues like this.
(Namely issues like abc = bca = cab).
<@&268886789983436800>
Please don't use ChatGPT, especially to answer questions from helpees @crimson sedge
@dire geode you know how to do it?
I couldn't solve it. So I Asked AI(Chat GPT). Sorry If I violated any rules.
If you can't solve it, then don't answer; answering using GPT and similar AI is against the rules
Ok
@crimson sedge Has your question been resolved?
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yo
is $\lim_{x\to 0^+}{\frac{1}{x}}$ equal to infinity or DNE
Jash
idk is there like a formal definition
so what would it be
Find $a$ and $b$ such that $\lim_{x\to 0}{\frac{\sqrt{ax+b}-3}{x}}=\frac{1}{3}$
Jash
well
for a normal right handed limit
it is something like
we say $f(x)\to L$ as $x\to c^{+}$ if $\forall \varepsilon >0:\exists \delta >0$ s.t $\forall x \in S$ with $c<x<c+\delta \implies |f(x)-L|<\varepsilon$
Austin
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x-5-x=-5
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determine the exact value of:
all of these have values you should know
like, every individual sin() and cos()
so you can just find those all
like for example cos(pi/3) is 1/2 ?
yeah
well you could try using that but there's no need
those formulas are so cursed
it should be an exercise for very strong students to derive them from the normal ones (sin(a+b), etc) and then completely forget about them after
oh ok i found out
In bold and in blue, the new features at the start of sup
thats what im going to see this year
it has nothing to do with the revision exercises of last years im doing
ah ok
what studies are you doing or did you do btw? @gritty viper
what are you planning to do?
alright i see, thats really nice
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como


