#help-27
1 messages · Page 320 of 1
why are there like 3 people using the same channel what
i was typing in the other help channel but then it got occupied, my bad
Let's restrict to the first condition
your good bro
well 300<n<500
n is the 3 digit number were talking about
the number has to be one more than a multiple of 3 +1
which is also 1 less than a multiple of 7
Where do whole number multiples of 7 start in the 300-500 range
As well as the multiples of 3
multiples of 7 +1
(The point is to find a "common factor" so we can just apply a simply rule)
300+x=7y
7,14,21,28,35,42,49,56,63,70,71,78,85,92,99,106,113,120,127,134,141,148,155,162,169,176,183,190,197
all multiplies of 7 in a range of 200
common factor for multiples of 7 plus 1 and multiples of 3 minus 1
You did not need to do allat
all of these are divisible
but too much work stone
meh
Let me demonstrate
brute forcing it works sometimes
yeah but in a competiton it kills time quickly
theres always a quick solution its hidden in the question
I guess you could use explicit arithmetic
The first starting factor 1 less than multiple of 7 is 302=1+43(7)
28 multiplies of 7 in 200
approx
66 multiplies of 3 in 200 approx
rounding down
Now $3y=2+7n$ so we have $$ 3 \vert 7n+2 $$ $$ 3 \vert n+2 $$ in other word
$ n = 3k +1 $ where $k \in\mbb{Z^+}} $
C
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3y=2+7(3k+1)
algebraic approaches is pretty confusing
now consider 300 < 21k+ … < 500 instead
n cant be a fraction
301 is the first multiple of 7 in that set and 497 is the last
300 + 7, 300 + 14, … 300 + 196
303 is the first multiple of 7 in that set and 498 is the last
304 + 0, 304 + 3, 304 + 6, … 304 + 195
rewrite the 7s
304 + 3, 304 + 10, 304 + 17, 304 + 24, 304 + 31, 304 + 38, 304 + 45, … 304 + 189
every third matches with a multiple of 3
how many multiples of 3 between 189 and 3
67
is that right
liek is 67 correct
multiples of 7 + 1
havent check
Oh by the way
yeah?
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alright
@valid vector i was trying to tell that guy that youd be more helpful than me 😭
i can cook on the competition with your help
last year i only threw biscuts everywhere
for fun
i didnt even try that much
this year im locking in
its overwhelming though
your the type of person who makes x+5=3 into a multidimensional calculus equation 😭
asy
your question say 3m+1 and 7n-1 but
?
I do not care, pricks are prideful and stupid 😄
"How many numbers between 300 and 500 are one more than a multiple of 3 and one less than a multiple of 7
it can both
i dont know man
you guys know everything i know nothing
let n be such a number
n = 1 mod 3 and n = 6 mod 7
so n = 13 mod 21
n is of the form 21k+13
solving modular systems like this is a result called the chinese remainder theorem
dang😢
maybe im not worth it
i cant do this
I’ll following your word then , since $$ 7n+1 = 3y-1 $$
$$ 7n+2 = 3y $$ and since $n,y \in\mabb{Z^{+}} $ we have $$ 3 \vert 7n +2 $$ which mean $$ 3 \vert n+2 $$
We have $n=3k+1$ consider $$ 300 < 7(3k+1)+1 < 500$$ $$ 292 < 21k < 492 $$ then $ k = 14,15,\dots,23 $
And since $ n= 3k+1 $ then $ n = 43,46,\dots,70 $
$$ 7n+1 = 301,323,344 ,\dots , 491 $$
its alright im not going to the competition
im a prick anyways whats the use
no one called you a prick
@valid vector was ref to another person here
no no no
its my opponent
im against the best high school in my county
i need your help
like actually
without you guys i might not defeat them
if you dont place first you dont place first you can do everything in your power to do ur best but like
ive been on both ends of that
ive been against better schools and ive been the best school
theres only so much you can do
i need help with variables like ABC38=something and word problems
can you give me an example?
Sorry if it’s not what you meant but here’s
111 = 100 + 10 + 1
123 = 100 + 20 + 3
Now if we look for ABC is three digits number we have ABC = 100A + 10 B + C
using that how can we solve questions like ABC+CB4=B6D or something like that
by doing what we did earlier
yeah or similar ideas, I mean it's just calculations in the end
no matter how you do them
however, if you're going to do a lot of basic arithmetic stuff, modular arithmetic would help a lot
alright lets try ABC5=50x
In other words , $$ \overline{a_1a_2\dots a_m} = 10^{m-1} \cdot a_{1} + 10^{m-2} \cdot a_{2} + \dots + a_m $$
i want to find the lowest solution
C
x is a digit ?
no its a variable 50*x
oh ok so a natural number
yep
so you want ABC5 to be a multiple of 50
which can't happen, bc multiples of 50 end in 0
yeah I told you
a multiple of 50 is a multiple of 10
so you make things... less interesting
8ABC=50x
A = B = C = 0 give 8000, a multiple of 50
that's the smallest in the 8000
but
you won't have a number in the 8000 smaller that 8000
8150
for a b or c
you add 50 until it meets condition
yes
to stay in the multiples of 50
so any variable equation thats equal to a random number times x
makes the variable also a multiple of the random number
wait where did the 1000 and 100 go
we can leave those
ah ?
A and B can remain the same
you're working on numbers here
A is a 4 digit number
a>4
In fact k can never be larger than 1000, coz left hand side can be no more than 9900
9900 is the max we can get
the mimimum is 1100
we need the closest number to 1100 that is 43*something - 42
if I have 1000A+100B+42 = 43k, an idea is to look mod 43
so 11A+14B-1 = 0
11A+14B = 1
1st step you can take is, since AB42 is divisible by 43, the last digit of k is gonna be 4
trial and error will be kinda long but yeah you can
860
not close
43(25
40+3(20+5)
860+5(43)
215+860
1075
1075-42
1033
1075+43
1118
1118-42
1076
1077
so on
That’s gonna be too long
Do you know long multiplication? The way you multiply numbers with pen and paper. You can do that and construct the unknown numbers with that
If you feel modular arithmetic is tough, you can always use long multiplication for this
so k should end with 4
43(25)+1 makes 1076
43(25)+25
=1100
43(25)-42=1033
43(26)-42=1034
it keeps on going up 1
with modular arithmetic:
AB42 = 1000A+100B+42 = 11A+14B-1 mod 43
so 11A+ = 29B+1 mod 43
A = 30B+4 mod 43
A and B are digits, where B is between 0 and 9
by calculating the ten 30B+4 mod 43, only two cases give A between 0 and 9:
B = 0 gives A = 4, B = 3 gives A = 94 = 8 mod 43
only 4042 and 8342 are multiples of 43 of this form
well this is certainly wrong
you know you'll have like 200 multiplications to do if you continue this way right?
i know
brute forcing isnt the way to go
i was desperate because i thought i saw a pattern
that statement was stupid
like, you add 43 each time
well
43(26)-42
43(25)+43-42
43(25)+1?
thats what i thought
but i might be wrong
you're not wrong
but you're only noticing that 42 = -1 mod 43
you would still benefit from using some arithmetic tho
if you learn the chinese remainder theorem, here there's still the "nice way" of doing it
conveniently, I chose 43 to be prime and the number ends in 42
so the number happens to be 42 mod 100 and 0 mod 43, which gives one possibility mod 4300
so we already know that there are at most two solutions between 0 and 9942
and the theorem also gives the way to compute them
then you find the two solutions 4042 and 4042 + 4300 = 8342
there's also a "pure modulo" way I illustrated earlier
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How does one treat this UDL extending on angle member?
@versed cipher Has your question been resolved?
@versed cipher Has your question been resolved?
What is a UDL?
Uniformly Distributed Load, the red one
I didn't understand the question, can you explain
Okay
there is a UDL on member BD , and on the left side, it is hovering above an angled member AB,
Should I disregard this excess? or is it part of the equation and would it be transferred to angled member AB?
Lol, this question is too advanced for my peanut sized brain
I feel the same way
T-T
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I am struggling with putting up the sums using the summation symbol
you need to figure out the rule by which the terms in each summation are obtained
some of these look pretty counterintuitive...
i got the first 3, but i dont know how to continue...
d, f and i think h may be quadratic sequences
given that the differences between adjacent terms seem to be constant
kind of painful to figure out exactly what those are tho
e is quite clearly the sum of a GP
i have no idea what d could be
yh i got that, but i just dont know how to express it into the summation symbol
well, how can you write the n'th term of the sequence {2, 4, 8, 16, ..., 1024}?
you said you get that it's a GP
do you know how to write down the n'th term of a GP
what is GP?
geometric progression
ah
why did you say you get it when you didnt even know what i meant by GP until now 
sorry, i understood it wrong
i dot
i dont usually do maths in english
so some of the terms are new to me
what's your native language
ok i dont speak that anyway
its fine haha
but how can i learn to build the sum of these things?
like i tried searching online, cant find anything. I dont know if there are set rules to follow
you should not expect yourself to be able to come up with a formula for an out-of-nowhere sequence of numbers
bc this is not really a thing that can be done at all
well, thats kind of what i need to do ... XD
but for 2, 4, 8, 16, ..., 1024 you can recognize these numbers as powers of 2
2^1, 2^2, ..., 2^10
i am talking about e
ok
do you get this
i think it's going to be something like $a_k = Ak^2 + Bk + C$ with some constants $A$, $B$ and $C$.
Ann
honestly it is kind of the best you can come up with if the first 3 terms don't follow any specific pattern and are all you're given
this exercise is dumb
haha
and this is the first exercise we get with this new topic, smh
weird ahh Teacher
just asked ChatGPT, he got this
but it only works for the first 2
i think im just going to skip it
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what does it mean when a variable is a placeholder
context?
let's say the electric field due to a line charge = lambda/(2pie_0x), is "x" a placeholder here?
well in the sense that it occupies some space and you later will plug in some other thing for it, sure
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$\text{Heavy or tall husbands}=470\\frac{2}{3}\text{tall husbands are also heavy}\\frac{1}{2}\text{heavy husbands are also tall}$
UCYT5040
how do i solve this?
If you just type words outside of the $ signs it will just be normal text
Like this $x = 3$
frosst
Draw a diagram id say
I honestly would say just start writing out the numbers
If two thirds of the husbands who are taller than their wives are also heavier
How many people is this
not sure
but i also just realized that means 1/3 of tall husbands are not heavier
but still not sure where to start here
i dont think its 470 because thats # of husbands that are tall, heavy, or both
<@&268886789983436800>
What is 470
Be specific
Ok and you’re saying 470 of them are what
I don’t think 470 is the right number
And let’s not use the opposite statements, let’s focus on what the question states for now
okay
2/3 of 530 husbands are what
i dont think they are anything
because not all 530 husbans are taller than their wives
Ok
Let’s suppose there are x husbands that are taller than their wives then
Now what would we say
2x/3=husbands both tall and heavy
Ok what about the other way round
like (3*(husbands both tall and heavy))/2=x
or did you mean with the other condition?
Yeah the other condition
ahh ok then y/2=husbands both tall and heavy=2x/3
where y=heavy husbands and x=tall husbands
Hmm
only 6% of test takers got this one right
so it must be pretty hard
oh and also the correct answer is 400 if that helps
This is very confusing indeed
So I would think about it like this
Red is both heavier and taller
Green is heavier but not taller
Blue is taller but not heavier
And outside is not taller and not heavier
There are 530 people in this diagram
outside is 60?
Look at this
So taller means red + blue
Also heavier ok
So red / (red + blue) = 2/3
Do the same for green
red/ (red + green) = 1/2
And we also have green + red + blue = 530 - 60
Ok let’s now call x = green, y = red, z = blue
So we have the 3 equations…?
Do you think you can solve this
i think so, let me try
y=188
z=94
x=188
that cant be right
y should be 400 right?
Doesn’t line 1 say y = z
There is some number z of people who are taller than their wives, of the z people, 400 are also heavier, and at a proportion of 2/3
Yeah
So then there are 600 husbands
400 is not correct
Unless they mean 1060 people are all husbands
We can try that
Oh that wording threw me off
I suppose 1060 married couples means 1060 pairs of people
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Yeah this first instinct was right
A diagram helps a lot
@lofty verge
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Especially with these prooortion stuff
It’s so hard to read and process and hold all that info in your head
Diagrams make it easy to see what’s going on
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I had a problem in another help channel but it closed after I fell asleep. Here's the problem restated:
Hello all. I have a problem that I have been stuck on and want some guidance on.
Say you have a Mafia game with x town and y mafia. The total number of players is
x+y, the combined total of town and mafia. The town win if all mafia are eradicated, and the town lose if there are ever more mafia than town. Assuming the town kills one random player and the mafia kills one random town every day/night, what is the probability that the town wins?I have made the following recursive formula:
f(x,y) = (x/(x+y))f(x-2,y)+(y/(x+y))f(x-1,y-1)wheref(z,0) = 1,f(z,z+1) = 0,xandyare positive integers, andx+yis an odd integer (trust me, this matters). It is easy to find a solution forf(x,1)with double factorials, but it seems that going any higher is harder. I would appreciate any help.
To clarify: I'm sure the recursive formula is right, but I want a general solution to the problem.
You problem seems to not be well defined
What is a player/how many players are there
a player is either a town or mafia
and it can be any positive (in this case, odd) number
essentially its just the combined total of all town and all mafia
i suppose i shouldve also said that mafia wins when there are more mafia than town and town wins when there are no more mafia
@ruby talon Has your question been resolved?
i edited the original post so thats its more clear
$f(x, y) = \frac{x}{x+y}f(x-2, y) + \frac{y}{x+y}f(x-1, y-1)$\\
$f(x, y) = $\
$\frac{x}{x+y}\qty(
\frac{x-2}{x+y-2}f(x-4, y) +
\frac{y}{x+y-2}f(x-3, y-1)
)$\
$ + \frac{y}{x+y}\qty(
\frac{x-1}{x+y-2}f(x-3, y-1)
- \frac{y-1}{x+y-2}f(x-2, y-2)
)$
Sepdron
@ruby talon Has your question been resolved?
yeah, just expanding it to try to make a pattern clearer
if we only expand the f(x-1, y-1) repeatedly, we get\
$f(x, y) = \sum_{n=0}^{y-1} \frac{(y)_n}{g(x+y, n+1)}(x-n)f(x-n-2, y-n)$\
where\
$(a)_b = a(a-1)(a-2)\dots(a-b-1)$\
$g(a, b) = a(a-2)(a-4)\dots(a-2b+2)$
Sepdron
@ruby talon do we have x>y here?
if not, what happens if it's like f(-1, 1)?
@ruby talon Has your question been resolved?
yeah we assume so
for initial conditions at least
obv "if mafia wins" you can get f(2,3) or f(4,5) (or generally f(z,z+1) but thats the only case that those values should be expected to be put into f
and in those cases its always 0
alr, I think it might be useful to make x=y+a then
also this is wrong, I misread something
this should be right I think\
$f(x, y) = \frac{y!}{(x+y)!!} + \sum_{n=0}^{y} \frac{(y)_n}{g(x+y, n+1)}(x-n)f(x-n-2, y-n)$\
Sepdron
$f(y+a, y) = \frac{y!}{(2y+a)!!} + \sum_{n=0}^{y} \frac{(y)n}{g(2y+a, n+1)}(y+a-n)f(y+a-n-2, y-n)$\
$f_2(a, y) = \frac{y!}{(2y+a)!!} + \sum{n=0}^{y} \frac{(y)_n}{g(2y+a, n+1)}(y+a-n)f(a-2, y-n)$\
Sepdron
interesting its less recursive now, per se
@ruby talon Has your question been resolved?
i wonder if, similar to how you found a pattern in the summations for one f, that you do the same thing for the second and end up with a double summation
oh wait no bc there would be a... new summation every recursion
i suppose i couldve pinged helpers but like whats the point lol
you could maybe try doing smth with generating functions
ok thats seems pretty useless
honestly i have a bad feeling there just isnt going to be a closed form
i thought looking at a simpler problem (y=1) might help and even that seems like there wont be a nice solution
$f(2n, 1) = 1 - \frac{\sqrt{\pi}}{2} \cdot \frac{\Gamma(n+1)}{\Gamma(n + \frac{3}{2})}$
Acman
$f(2n+1,1) = 1 - \frac{2}{\sqrt{\pi}} \cdot \frac{\Gamma(n + \frac{3}{2})}{\Gamma(n+2)}$
Acman
so you get $(1 - f(2n+1,1))(1 - f(2n,1)) = \frac{1}{n+1}$
Acman
idk if that means anything, i dont see this generalising in any way tho
i suppose using these results its possible to probe a bit deeper at f(n, 2)
but thats getting messy real quick
unless ive made an error somewhere
$f(2n, 2) = \frac{1}{2(n+1)} \left[n - \frac{\sqrt{\pi}}{2} \sum_{i=1}^n \frac{\Gamma(i)}{\Gamma(i+\frac{1}{2})}\right]$
Acman
$f(2n+1, 2) = \frac{2}{2n+3} \left[n - \frac{2}{\sqrt{\pi}} \sum_{i=1}^n \frac{\Gamma(i + \frac{1}{2})}{\Gamma(i)}\right]$
Acman
oh and wolfram is being very kind and saying those sums can be simplified
$f(2n,2) = \frac{1}{2} - \frac{\sqrt{\pi}}{4} \cdot \frac{2n+1}{n+1} \frac{\Gamma(n+1)}{\Gamma(n+\frac{3}{2}}$
Acman
$f(2n+1,2) = \frac{2n}{2n+3}\left[1 - \frac{4}{3\sqrt{\pi}} \cdot \frac{\Gamma(n + \frac{3}{2})}{\Gamma(n + 1)}\right]$
Acman
i was hoping theyd both end up in the form $q(n) \left[1 - C \frac{\Gamma(...)}{\Gamma(...)}\right]$
Acman
for some rational function q and constant C but alas
though perhaps we can posit that $f(2n, m) = p_m(n) - q_m(n) \frac{\Gamma(n+1)}{\Gamma(n+\frac{3}{2})}$ for some rational functions $p_m, q_m$
Acman
and a similar result for f(2n+1, m)
i hope that a) i havent made any (serious) errors and b) any of that is of use to you haha
if you want me to explain how i got any of these feel free to ping
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Can I calculate a) using the impulse formula? I tried it doesn’t give me the correct answer so idk
how to use this bot?
@true vapor Has your question been resolved?
https://en.wikibooks.org/wiki/LaTeX/Mathematics and also this help channel does not belong to you
°
One of the greatest motivating forces for Donald Knuth when he began developing the original TeX system was to create something that allowed simple construction of mathematical formulae, while it looking professional when printed. The fact that he succeeded was most probably why TeX (and later on, LaTeX) became so popular within the scientific...
no, you need to use conservation of momentum of a)
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A tournament is a (directed) graph with exactly one edge connecting a pair of vertices (with the edge directed in one of its two possible directions). A king in a tournament is a vertex $v$ that can reach all other vertices within two steps. That is, for all vertex $u$ other than $v$, we have either $v\to u$ or $v\to w\to u$ for some $w$. I'm trying to prove the claim that every tournament has a king. \
I'm just looking for feedback for my proof. I'm a bit uncertain about the conclusion. \
Proof. Let $v_1$ be an arbitrary vertex. If $v_1$ is a king, we are done. If it isn't, this means $v_1$ can not reach some vertex $v_2$ within two steps. This means the out-degree (i.e. number of outgoing edges) $d^+(v_2)$ is greater than $d^+(v_1)$. This is because we have $v_2\to v_1$ (recall it's a tournament) and if $v_1\to w$ for some $w$ then we have $v_2\to w$ (otherwise we'll have $v_1\to w\to v_2$, contradicting that $v_1$ is not a king). Continuing this way, we can find $d^+(v_1)<d^+(v_2)<\cdots$ and terminate at some vertex $v_k$ since there are only finite number of vertices.
psie
Now, is v_k a king? Can I just argue by contradiction and claim v_k has to be a king?
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hi
y = ln x^e^x
how do I do this?
since:
u = e^x
u' = e^x
please correct me. this is my solution:
y' = (1/x^e^x) (x^e^x)
y' = x^e^x / x^e^x
y' = 1
y' = (1/x^e^x) (x^e^x)
how are you getting that
@odd elk Has your question been resolved?
based on the given formula from my prof
sorry for the late response
what formula
ok, but your u here is
x^e^x
yeah
not e^x
so what is it supposed to be?
oh wait the first one was correct
what first one
the given before I edited it...
since:
u = e^x
u' = e^x
is incorrect
you're starting with
$$y = \ln(\red{x^{e^x}})$$
in your first layer of chain rule, $u = \red{x^{e^x}}$
ℝαμOmeganato5
okay then what next
first apply that
to what formula
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✅
.reopen
first apply that
how 😞
exactly as the formula says
oh to the formula from earlier
okay wait
leave u' as u' for now in this first step
got it sir
oh then 1/x^e^x
no
can I use logarithm properties instead? is it possible?
no
don't overthink
this is an exercise of simple replacement
you already have everything needed for this step
you mean i'm cancelling out u' for now, right?
no
then wdym by leaving u' as u'
u' is u'
don't do anything with it
just leave it there exaclty as it is untouched as u'
do not attempt to differenitate that in this step
then this is it
oh then (1/x^e^x)(u')
yes
alright
that's the first application of chain rule
$$y' = \frac{1}{x^{e^x}} \cdot u'$$
$$y' = \frac{1}{x^{e^x}} \cdot \blue{(x^{e^x})'}$$
ℝαμOmeganato5
now you apply chain rule again for the blue part
then it is x^e^x for the blue part
don't do this in your head
noted
this derivative is actually quite tedious
and requires a few applications of chain rule
if you had a^u, yes
but your base here is x, which makes things more complicated
oh yeah, nvm nvm
you know what, I quiti
i'm sleepy i'll just do this tomorrow
i'm starting to see the actual pattern, but i'll continue this instead since I can't fight the tiredness
thanks man! @winter patrol
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I need to solve 16a, all I've done so far is written a composite function, that is equivalent to f^3(x)
but i don't see how that helps, since there are 3 unknowns (or well the x isn't a problem really, but a and b being in the same equation is)
uh a(a(ax +b)+b)+b
And when you develop?
gimme a sec
a^3x + a^2b + ab + b
Seems good
Yes
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integral of 1/(x^4- 2x^2 - 3) dx
original question was
integral of 1/([x^2-4] root{x+1})
i took x+1 = u^2
got x^2-4 as the denominator
i have this in form of u
if i take x^2 here at t so 2xdx = dt dx=dt/2roott
so this becomes 1/(2{root t}[t^2-3t-3])
now t = smth else ^2 i tried and it just a circle
got back to here
I don't think you need to
You can factorize x^4-2x^2-3
Hint: ||Let u=x^2||, but not in the integral
Then proceed with partial fractions
mere sub?
?
mere substitution?
What I want you to do is
You don't need to sub in the integral
just used to simplify and factorize or find A B C in partial fractions
Someone help with 2 4 and 5 please
$\int\frac{1}{x(x^5+1)}dx=\int\frac{1}{x^6(1+x^{-5})}dx$
;(
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@lusty tapir This is a really nice technique known as the "Caveman Technique"
oh
so name take x^-5 = t
bring x^6 to numerator
we get -5log |1+t| + c
yayyyy
first time hearing about it
my teacher didnt teach with name of techniques or any technoques he wants us to just use our own logic and figure it out
Lol
can you tell me names of other such techniques?
i know there DI for uv integation and kings smth smth but idk how to do them
@lusty tapir Has your question been resolved?
I can't really name them off the top of my head
@lusty tapir Has your question been resolved?
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hello
requesting help with this problem
we are given the function f(x) = ax^3 + ax^2 + x
determine how the amount of critical points
is dependent on the value of a
and the character of those critical points
I've derived the function and completed the first part of the question
don't know how to get the character of the points
vengeance
I used the quadratic formula yes
Then just use determinnat
if determinant>0, 2 real sol
if determinant=0, 1 real sol
if determinant<0, no real sol
Just analyze when discrim>=0
f''(x) = 6ax + 2a
You're supposed to get -11 + 3√3 for the first part. And in the [2-1], it's actually [2-18]. Therefore, the final answer would be 5 + 3√3 as intended
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Can anybody help me with this problems ive been trying for hours and i dont know what else to input
Share the problems
Don’t ask people to commit before they’ve seen the problem
how did you conclude C=2? and what's that 12B/12 doing on the other side of it?
also that's a weird way to write pi
Thats the formula for finding the period
Can anyone in this discord actually help me
ok first off please hold off on the entitlement.
2pi/B equals the period, yes.
but the way you wrote it, in the place where the period is supposed to go, you put 12B/12 -- which is just B.
i'm asking you what's up with that.
To get B on one side
what is the period of your function as read from your table of values?
12
are you sure?
No
the entire interval covered by the table is [0, 12] which does have length 12, but does that constitute exactly one complete period?
i, for one, don't think so -- you've got those 2's in the y-row which are not 12 units apart on the x-axis.
do you see what i am talking about?
@trim quarry
ok imma need to disappear for a few
A little
Im still working through it
Try period 8 which is pi/4
I redid this is what I got so far
ok the inside of the sine is now correct but the amplitude and midline arent
your formula has the midline as 0; surely this isnt the case?
so you're certain the midline is 0?
Not in the first solution I sent but I change it in the latest photo to 4
The amplitude I counted from one end to the other and got 8
i do not see midline=4 in this formula. i see no D term at all, which as-written would mean it's zero. is it cut off?
wdym by "one end to the other"?
i think maybe you are confusing yourself, or not articulating yourself well about what you did, or some mix of the two.
I can draw a line if its easier
but the highest and lowest y-values are 6 and 2 respectively.
the difference between them is 4.
half that gives the amplitude.
brackets!
you can get the amplitude by many different ways.
you can either take (max - min)/2.
or, if you already know the midline, you can find it as |max - mid| or |min - mid|, no halving.
Ill use this formula from now on
And you said my period is correct?
your period and phase shift are, yes.
also, if you're using desmos, you can always write your formula into it to have that graphed alongside your points.
so you can easily see if your graph matches.
this 4?
What do you want me to do im not good at math im trying
i want you to stop trying to hold a million things in your head and mess them all up, first and foremost
Ok, right now 2 is the amplitude pi/4 is the period and so now I just need to figure out D and C to finish the rest
the general formula for a sinusoid is: $$y = A \sin\paren{B(x-C)} + D$$ where:
\begin{itemize}
\item $B$ is the stretch factor, which indirectly controls the period -- in your case, $B = \frac{\pi}{4}$ is correct
\item $C$ is the phase shift, which for you is $4$ --- and $4$ was correct, and you had no reason to change it now
\item $A$ is the amplitude, which in your case is $2$
\item $D$ is the midline, which in your case is $4$
\end{itemize}
Ann
i hate to say this, but
task failed successfully
what is that =4 doing? why isn't it a +4?
i can understand the dropped y=, but the plus sign should not have transmogrified into an equals.
@trim quarry Has your question been resolved?
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pls someone help me idk where to start
Applies the logarithm in the equation
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Slope fields
I'm not sure how to get the answer
dy/dx=0 at y=-1
However, when you differentiate all of the equations, they all only have x
This is saying that when y = -1, dy/dx = 0
so you can solve for the value of x such that this happens in each case
and check if dy/dx is indeed 0
but this is too much work
Just recall that you can "trace" the solution in a slope field
since we have that the graph of the particular solution goes through (0,0), the graph of the particular solution looks like this
it should be a bit "smoother", but you get the idea
i see, but if we use the graphical approach, then how do we know it is y=e^(-x)-1 instead of y=e^(-x^2)-1?
$e^{-x^2}-1$ is symmetric abt $x=0$
Civil Service Pigeon
(note that this is the same thing as saying that the function is even)
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Prove that in worst case if you apply pruning in an Voracious algorithm for solving for example TSP The complexity in worst case with Big-O notation will still be n!. How could we prove this
I want to understand it deeply better
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Plz I need help on trigonometry
Please don't occupy multiple help channels.
Plz can u help me with trigonometry
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<@&286206848099549185>
this is my first time asking questions on this discrod server, is this how I do it?
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oh okay, my bad, first time doing this
Apply the formula of volume of a cone, and substitute the values. You should find a relation between the big and small one.
(I'm uncertain on this one, but I guess it's worth a shot)
so the volume of the icecream is 9 pi
but I still don't know the radius of the icecream
How did you get it?
isn't the volume of the cone 18 pi?
My bad, you're right. I thought you meant the big one is 9 pi.
and if it says that the volume of the ice cream is half the volume of the cone, than doesn;t that means the volume of the ice cream is 9 pi?
You should find a ratio of $$\frac{r_s}{r_b}=\frac{h_s}{h_b}$$
Good
You know $r_b$ and $h_b$, now isolate $h_s$.
Good
@copper sigil Has your question been resolved?
Hey sir! I am just curious about that question . Is the answer 4.76?
It would be awesome if u could help me check 🙏
now i'm even more confused
😭
I solved it this way I am no sure if this works
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wait, I think you solve this using similiar triangles
What’s that
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wait, give me five minutes to solve it, I send a picture to you after
Oki thanks
What’s that
so if the ratio of volumes is 1/2, side ratio would be 1/cbrt(2)
it's like triangle abc is similiar to triangle edc
Oh fire
Ohhh
Is that the real name for similar triangles ?
it is close to it
Oh
like
Thanks
you welcome
I got 7.35 cm
Hi pro , do u think u can calculate that answer
We got different answer we dun know who correct
sorry for the messy handwriting and working out, but that's how I got the answer
Thanks
yeah same as you
use my method
certified method fr
oh okay, thxs
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eugene
Should I be using Partial Fraction Decomposition'?
What am I trying to find here in Problem 3?
Expanding the generating function?
from where you all get these questions?
on my paper
do you get paper as softcopy?
I have both but my work is written on physical paper
ok
Im going to use Partial frac decomp and then find the simplified gen function
but i am not sure why i am using my previous recursion
this question is of which grade?
its combinatorics
grade?
undergrad
?
wdym grade
ok
nvm i dont think i am using PFD
$a_n=a_{n-1}+n$ for $n\ge1$
ロケットジャンプ
use this to compute the generating function
$$f(x)=\sum_0a_nx^n=a_0+\sum_1a_nx^n$$
ロケットジャンプ
Ohh okay
btw those sums are 0 to infty etc
@vocal mural Has your question been resolved?
if the index range is clear then we can sometimes even leave it out entirely 🙂
that just feels weird though 😭
$\sum a_n$ enjoy