#help-17
1 messages · Page 204 of 1
Or that
was wondering why do you want to open it infinitely, unless you're opening schrodingers box or something
I just thought that it didnt seem as random if we were throwing out the bad choices
its more like searching
,w sum 1 to inf of n^2/2^n
You have also $\mathbb E[g(X)] = \int_\mathbb R g(x)f_X(x),dx$
Ik we don't need it im just curious
well I don't understand why this shoud be the definition
why would it not be P(X^2) * value X^2
remember that you have to be careful when you open a box, the price to no price ratio is not 1:1
That’s true but then you need the pmf of X²
I don’t know I haven’t read that far 😭
But I do know you can just let Y = X² then you can do E[X²] = E[Y] = sum P(Y=y)y
why would it be times value X^2?
Which would be what you said
why would it not be? thats my whole doubt
expected value of X^2 = mean value of X^2 = sum of nP(X^2 = n)
but P(X^2 = n) is zero unless n is a square
why weight it with X^2 but not the probability of getting this weight?
.reopen
✅
as it should be
YESSSS WHAT INFINITE TIMES
but why weight the possibility that X=m with m^2 instead of m?
because i did the change of variable n = m^2
⚔️
before the change of variable you had the sum of nP(X^2 = n), but that's zero for all non-square n
I see the issue
E[X^2]
I'm like okay, I want to know what the expected value of the r.v X^2 is so
it can take on 1, 4, 9, 16, ...
1 * P(X^2=1) + 4 * P(X^2=4) + ...
but this is
1 * P(X=1) + 4 * P(X=2) + ...
I seee
thank u dark side gf
@thin vale r u good or u want me to read it
yep
im good
tbh, jumping straight to the law of the unconscious statistician makes things easier
f_X(x) is like a density function and g(x) is the coordinate, E[g(x)] is like the center of mass
if physics helps
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How do I find x?
can you send a full screenshot
hmm
Equality
im kinda bad at geometry tbh
how can you write DC in terms of x?
20-x
64-x^2 then square root
Do you draw a line from A to C
reread the problem statement
Well
theres another statement in the question
what does the last sentence say
thats the key to solving it
Let Hyp = H
Then 20 - x = H (given)
Use pythogoras
H^2 = x^2 + 8^2
Sub and find
Solve quadratic
The answer is 8.4km
I hate these questions, so calculative
I don’t know why tho
oh my god can we let me finish
are there any inequalities you can create
given the 2 lengths
mb not inequalities
but like
2 equations that equal eachother
CD = AD
yeah
good
and what are the lengths of those
400 + X^2 - 40X = X^2 + 64
Wow
X^2 gets cancelled
400 - 64 = 40X
336/40 = X
X = 8.4
a) AD = 20 - X
b) DC = 20 - X
c) BD = X = 8.4
Bruh pretty easy
Wats the answer
Given?
336=2x^2
and then what else can you do to simplify
!noans
The purpose of this server is to help you learn, not to hand out answers. Do not ask someone to give you the answer directly.
holy heck
how did you get here
i might be slow
(20-x)^2=64+x^2
ok
retry on the hypotenuse
how would you expand the (20-x)^2
yeah i think you accidentaly pressed - lol
youre welcome
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!nosols
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what does d4 mean
4th decile i think
ohh alright
do you know how to answer or solve that
im not v good with statistics and percent 😭
Do you know how to find median?
yes
And quartiles?
ok tysmm
Also
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✅
It is asking for D4 so?
What would be Q3?
3/4
Yeah practice set
What is it called
I also need to practice some stat mcqs
Sure, if you don't mind
Thanks
thanks too ^^ !!
Now you can close if you want
.close
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hello, i have to do a triple integral in this region x^2+(y-1)^2+z^2<=1, the bounds i set in polar coordinates are
x=rcos(phi)sin(theta)
y=rsin(phi)sin(theta)+1
z=rcos(theta)
jacobian is r^2sintheta
is this correct?
forget that, so the region is a square right? so in conversion i had theta and phi both run from 0 to 2pi, is this correct?
should be a sphere
yeah mb
its a full sphere so on conversion the xy plane angle runs from 0 to 2pi, same with the z angle right?
why is that?
@restive whale Has your question been resolved?
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if im at 100k
and i need 360k
i will exchange 10 stuff for 1500
how many stuffs i need for total 360k?
<@&286206848099549185>
@cedar canyon Has your question been resolved?
You need 260k
260000/ 150 = 1733.33
You need 1734 stuff id say, as its better for context
if 100 = 1 stack
so it is 17 stack half?
Yes 18 so
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ok man, no need to flip us off
bruh 😭
@atomic mica Has your question been resolved?
Okay
can i dm u privately
Whay happend with prob befor
i ain’t read it properly
You should post it here
it’s fine i’ll just ask it tmrw
As i might not be available
Ue
.closs
Yw
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I need help to solve these equations
,, \begin{cases} 2(x-1) = 3(y+2) \ 2y + 3 = 2(x-y) \end{cases}
938c2cc0dcc05f2b68c4287040cfcf71
well
,, \begin{cases} 2(x-1) = 3(y+2) \ 2y + 3 = 2(x-y) \end{cases} \ \begin{cases} 3y + 6= 2(x-1) \ 2y + 3 = 2(x-y) \end{cases}
938c2cc0dcc05f2b68c4287040cfcf71
What do i do to find the x and the y
isolate the y on one side
2(x-1)=3(y+2)
multiply the 2 through the first parenthese and the 3 through the second
you should end up with a y=something for both equations
right
so now isolate the y variable
start by moving the 6 over
2x-2-6=3y, is that how i do it?
That makes 2x-8=3y
Y ÷ 3?
yes, but make sure to divide the other side by 3 as well
what exactly is the question?
Indonesia
oh it just says "solve"
ok
alright so the first first equation, what did you get?
after dividing both sides by 3?
Wait lemme calcculate
fractions will probably work best
please dont solve the equation for them
2/3(x/3-1/3)=1(y/3+2/3)
uh'
from here
I dont learn fraction yet
If i remember correcty, 1/10 = 0,1
divide both sides by 3
it might be better to solve the system of equations by elimination of 2x, no?
1/10 is a fraction btw
right
Now, what do i do about it
Alr
and isolate y again
well what did we start with last time
you will combine the y's eventually
but we need to get rid of those parentheses first
it doesnt matter which y
Dont tell me we have to divide both sides with 4
Alr
and you'll be dividing by -4 on both sides once youve moved the 2x
-2x+3=-4y
yes perfect
2x/4-3/4=y
yep!
Does it have to do something with 2x/3-8/3=3y/3
2x/3-8/3=y
2x/4-3/4=y
if you were to plot these equations, they are two straight lines on a graph
Just saving it
yea np
Do i need to subtract both equation?
now set them equal to each other
x/6 = x÷6, or do i need to turn it into decimal
no there should be another side to your equation
i see what you did, you did it correctly, but you forgot about your other numbers
-3/4+8/3
close
32-9
wait
a;sdlfkj
sorry yes
that is correct
sorry my brain is shutting down
do i need to turn the x/6 to 2x/12?
exactly
Y÷3
multiply it by 6?
x=46
hol up
$\frac{23}{12}\cdot\frac{6}{1}$
32 × 6 = 192
hmmmm
Wumbo
shoulda been 23 right?
from here
Then, 23×6
138?
yea
Lemme do what i call in my language porogapit
12×1 = 12
138
12
18
Some problom here, 18 cant be divided by 12
the answer is not a whole number
Oh
it's a fraction
11,5
yes
alternatively you couldve done the calculation with the fractions
23/2=11.5
so x=11.5 yes?
So, x=23/2?
yes
Alr, now we found the x, we need to find the y
correct
all you need to do is plug that value of x back into either one of those first two equations
It can be any of hose 2 equations?
and solve for y
it can yes
what you're actually finding is the intersection point of two straight lines
2x/3-8/3=y
2x/4-3/4=y
.
yes
perfect
So,
X=23/2
Y = 5
well done!
Alr thanks
no problem!
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John has 4 apples in one hand and -1 apples in the other. Now suppose he puts the 4 apples through a square rooting machine and the -1 apple through a squaring machine. How many apples does he have now?
!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
@boreal remnant
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@boreal remnant is such a troll lmao
wdym?
i mean, the task makes no sense, but still
i say we would have 0 apples, but 3 apples^2
i think theyre trying to spread wildberger propaganda through this idk, have seen them claim real numbers are not real etc
channel is already closed
a mathmetican who well has a certain grudge against analysis for example, but for really odd reasons
a google search would be better tbh
ah now i find him, google only showed my a german manager lol
ah lmao
well this depends, when it says 'now' are we implying that this is after they have ran through the machine, for all i know they could still be in the machine being processed
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hey chat, i am once again stuck in a basic trigonometry question
the question wanted me to find all the sides
no idea how to start this, so any help would be appreciated ^_^
AB=x
BC=8
angle ABC=60
what's the exact wording of the question
are you omitting anything
yeah bcuz atm it seems theres not enough information?
are you sure?
please triple check
that what you've sent here matches exactly whats been given to you
!original
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
or if possible, send a pic of the original
then write it is impossible to calculate
if x is variable
its in another language so i cant really post it here, ill just skip this question
x is variable?
yes
i think i got what it meant
you can calculate other side in terms of x
so i think that's what question want you to do
the best you can do is express AC in terms of x
cos(60) = (8^2+x^2-AC^2)/16x
Oh, yeah thought x was to be found
huh, i see
you can get AC
Better to say what theorem youre using than to just give the answer
aight, thanks ^_^
(also starting with a suboptimal form of said formula/rule)
i think it is basic equation, not the answer, you simply it yourself
not the issue being addressed
yeah that too lol
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i hope you learned anything?!
lmao
i learned that i dont like this question! ^_^
the relevant formula here in case you didn't already know is
cosine rule
aka law of cosines
yeah, thats the topic im supposed be learning
its okayish for me but when variables come in im just lost 
hopefully ill get it til tomorrow ^_^
bruh the new champ aint even out yet

yasuo>>>
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use a new chanel
.
good question tho
@molten remnant read
yes
ok
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all atomic propositions are compound propositions. this is wrong, am i right?
@hard wren Has your question been resolved?
@hard wren Has your question been resolved?
yes. compound proposition is more of the combinations of the atomic propositions
@hard wren Has your question been resolved?
I know compound proposition is combination of 2 or more atomic proposition but atomic propositions are unbreakable so how can they be considered compound
Sorry I don't get your reasoning
I am saying yes to your "this is wrong"
Btw can I say all compound propositions are atomic propositions?
No right?
Atomic is irreducible but compound is still reducible, no?
Yes compound is reducible
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Wanted to know if my proof is correct
@deep bough Has your question been resolved?
<@&286206848099549185>
Not this again
my first comment would be to justify the use of a change of eps
so mention eps>0 anyway
If you managed to right this , then I don't think you'd need correction
It looks just right
just write*
I’m asking in case I made some type of error in an implication somewhere in my proof
no errors in logic
looks fine
(i am assuming that says lim sup for lim with upper bar)
Epsilon is defined to be 1/k where k is positive so I kinda just assumed I would be fine without writing eps greater than 0
Yeah that means lim sup
yeah you're fine then
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question is prove that (1) and (2) are equivalent
for 1 implies 2, I was a able to prove the left hand part of the inequality, but dont know how to show the right hand part
@stuck moss Has your question been resolved?
@stuck moss my guess is that
its possible to immediately get $\frac{f\qty(x_1 + t(x_2-x_1) ) -f(x_1) }{ t } < f(x_2) - f(x_1)$
jan Niku
which suggests a substitution
but hmm
id have to track it out its not really jumping out at me how it sorts out
obviously at some point you need to scale that interval
so you could maybe even do that immediately
yea I did that already
But it would only give the left hand inequality
I don’t know what to do for the right hand
sorry ill have to mess with this a bit
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i swear this question is impossible to do 
x is between x1 and x2 strictly
so x = x1 + t(x2-x1)
for some t
yea that would only prove the left hand inequality
we need also to show
you can exchange them as well
so x = x2 + t' (x1-x2)
have you applied it to that?
wdym
like
you used 1) writing x = x1 + t(x2-x1)
to justify f(x) < ...
and get the first inequality
but what if you wrote x = x2 + t' (x1-x2) instead
and applied 1) writing x like this
what I did was let t = (x-x1)/(x2-x1)
sure and you got " x = x1 + t(x2-x1)"
what I'm telling you
is to let t' = 1 - t
and see where it gets you
ok ill try, ty
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It has been a while since I have graphed piecewise functions and I can not remember how. I tried looking it up and doing some practice problems but still can not figure it out.
Graph y=6x+1 but only for x<-1
You follow the function in the range thats given, so for all values less than negative 1 (to the left of negative one) you would graph it as 6x + 11 until that point
Open/closed circle is also important if you don't remember that I can help as well
I do not remember that either
It's been a while for most of my algebra topics so I may be unfimilar with some of the basics. I'm just trying to regain some of my previous skills due to upcoming classes.
Alright well lets start with 6x + 11 do you know how to graph that confidently up until x = -1
Yes
What I understand is the 6x+11 part and all that and I believe its saying I need to do something for every x value less than -1 but im not sure if thats correct or how to procede from there
<@&286206848099549185>
Correct. You are supposed to graph it for all values less than (to the left of) x=-1
And as the other definition for all values greater than (to the right of) x=2
In between those two, it's not defined, so you don't draw anything
so for 6x+11 i how would I graph that
As y=6x+11
like I know what the question says and how to read it but I do not understand how to put it on paper
oh okay
yeah I see now
thanks
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Is there any intuition behind this skyscraper of a formula
I’m pretty sure there is, but I can’t quite recall atm
tried searching for something online and found a formula to approximate degrees of freedom that is way above my pay grade
i think the main idea is that you want to standardize the 2 samples, which gets you to the bottom of this
then now you want to compare 2 T(n-1) distributed numbers
but it's T(n_1 - 1) and T_(n_2 - 1)
T is the t-distribution?
yeah
then if you look at how the t-distribution arises
it happens when you divide a standard normal by a chi-squared/it's degree of freedoms
and you need the standard normal and chi-squared to be independent
it turns out using the unbiased estimate for the sample variance is indepdent to the sample mean
so you standardize the sample mean (now it's Z(0, 1))
but when you expand it on the bottom from the standardisation you get a chi^2 distribution
that gives you the t-statistic and you look at the ugly ass denominator for what the df of this statistic is
sorry im kinda a dumbass, what does this mean really
and how would you go about standardizing the sample mean
I think you also need the Welch–Satterthwaite equation that approximates the degree of freedom of chi-squared.
oh yeah thats the complex formula that i found
um
this guy is not exact i dont think
because we're just estimating the population parameters
but the distribution of the things is still good
So, suppose you have $X_1,\dots, X_n \overset{\mathrm{iid}}{\sim} \mathcal{N}(\mu,\sigma^2)$ then $\frac{1}{n}\sum_{i=1}^{n} X_i \sim \mathcal{N}\left(\mu, \frac{\sigma^2}{n}\right)$
nobody
Since the sample mean is normally distributed, Let$\bar{X} = \frac{1}{n} \sum_{i=1}^n X_i$, then $\bar{X} - \mu \sim \mathcal{N}\left(0,\frac{\sigma^2}{n}\right)$
nobody
and thats standardized?
nobody
We want variance to be 1, so we divide it by $\sqrt{\frac{\sigma^2}{n}}$
nobody
oh so basically its that z formula from normal distributions
yes
that what they meant by standardizing
https://www.itl.nist.gov/div898/handbook/prc/section3/prc31.htm here is one of the derivation of similar pool variance
hmm
i've gotten up to here
but you can't just compare these z's since they aren't the same degrees
you can't really do analytical work to get there because that is approximated
oh right
im pretty sure there's a way to get to this in a very sensible manner
i just cant remember off the top of my head atm
I remember there is one if you do it in high dimensional
like there is a nice property of chi-squared and Wishart you can use to get there
but also don't have that on top of my head
anyways, just in general. People in statistics use Welch–Satterthwaite equation to estimate the degree of freedom (as that can approximate the degree of freedom of the chi-squared)
Problem with the two-sample t-test is that the it is not exactly chi-squared but can be approximate using chi-squared
im gonna try find my notes on this
first answer here can give you the rough idea on how they approximate that chi-squared distribution https://math.stackexchange.com/questions/1746329/proof-and-precise-formulation-of-welch-satterthwaite-equation
ah yeah im getting there
@edgy gulch Has your question been resolved?
oh well guess you cant understand everything in a first year statistics course
thanks guys
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is there a way to uniquely define each knot up to ambient isotopy, assign each knot to something such that any two knots assigned to the same thing are the same knot up to isotopy
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guys help me ah
do a change of variables to polar
Yeah I'm also seeing a radius
alr do that tho but idk if it correct or no(so bad at complex thing) $\int_{0}^{2\pi} \int_{0}^{1} \frac{r}{(r^2 + 1)^3} , dr , d\theta$
looks right
Kol
do you know how to solve the inner integral?
yup
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does this proof work?
the problem statement is at the top of the first screenshot
you made a typo in the inverse and said its from X->Z instead of Z->X
Maybe include more details about why the composition of inverses is fine. Otherwise it looks good
now do homotopic
@tawny nacelle
ah, did I?
shoot, I did
which details are you talking about?
which section needs more?
why is psi compose phi inverse well defined
it might not be necessary to include but its just because all the domains and ranges line up
right?
well if psi:X->Y and phi:Z->W bijective it doesnt mean u can compose them if W!=X
thats all I mean
right, but the codomain of phi is the domain of psi
exactly
im saying maybe just say that

🔠
@thin vale is this okay?
looks good to me although i dont really know if thats the proper usage of "well defined", its just what I called it
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The point P has position vector (1, 5, 6). show that the perpendicular distance from P to the line AB is equal to root3.
and previously i solved AB position vector is (1, -2, -3)
all i wanna know is the answer let’s PQ be (3, -5, -5) + landa(1, -2, -3)
why is PQ that
they let Q be the point on AB that makes the perpendicular line PQ btw
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help pls
What's the vector equation for AB
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I'm trying to use Mayer-Vietoris to compute cohomology of S^n (n > 1) using induction (so H^q(S^(n-1)) = R for q = 0, n, otherwise = 0). But I'm getting the dimension of H^0(S^n) = 0?
The long exact sequence starts $0 \rightarrow H^0(S^n) \xrightarrow{i} H^0(U) \oplus H^0(V) \xrightarrow{\delta} H^0(U \cap V)$
Wheeler
U, V are hemispheres diffeomorphic to R^n, and UnV deformation retracts to R^(n-1). Then using Poincare lemma, H^0(V) + H^0(U) is just R^2 and H^0(UnV) = R by induction hypothesis
However it seems the dimension of im(delta) is 1, and by exactness the
Oh nvm.
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I gotta integrate this
Integration by parts would work
Let u = ln(t+1) and v'= 1/(t+1)
Put the 80 infront of the integral by linear propriety
,w integrate (80ln(t+1))/(t+1)
i could js substitute ln(t+1) = u
that would give me the same ans as wolfram
As you want mate
It will
,w derivative of lnx
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,w integrate (tanx)^4
Integration by parts
Or no
Wait
Tan^4 = tan^2 * tan^2
Tan^2 = sec^2 -1
So tan^4 = tan^2(sec^2 -1)
Tan^2 * sec^2 - tan^2
Let u = tan(x)
du = sec^2 x dx
So its 1/3(tan^3(x)) - tanx + x +c
So ye no need ibp for this one
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the question how can the circle showsn in the figure help us to locate pi on a number line
is that like
C = 2pi*r
as radius is 1 then
C = 2pi
so if we got the circuomference by rotating the circle on the number line
then divide it by 2
we get the pi
is thats the solution?
or you just rotate it halfway around
🧠
lol
yeah
true
thank you
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or take 0.5 as the radius.
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any idea how is this solved? (im asking for a friend so i don't know the specifics)
@lethal warren Has your question been resolved?
<@&286206848099549185>
@lethal warren Has your question been resolved?
@lethal warren Has your question been resolved?
it is correct yes
@lethal warren Has your question been resolved?
@lethal warren Has your question been resolved?
@lethal warren Has your question been resolved?
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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
my solution:
5c^(2/5) - 11c^(1/5) + 2 = 0
u = c^(1/5)
(5u^2)^1/5 - (11u)^(1/5) + 2 = 0
5u^2 - 11u + 2 = 0
5u^2 - 1u - 10u + 2 = 0
u(5u-1)-2(5u-1)
(u-2)(5u-1) = 0
u - 2 = 0 or 5u - 1 = 0
u = 2 or 5u = 1
u^(1/5) = 2 or u^(1/5) = 1/5
u^(1/5)^5 = (2)^5 or u^(1/5)^5 = (1/5)^5
u = 32 or u = 1/3125
eliminate the extraneous solution
u = 32
<@&286206848099549185>
am i right or wrong?
Yes!
hmm?
i forgot to replace some variables
You asked for wrong or right lol
I don’t see anything wrong here
umm
your last step is little weird
you have written
u^1/5 = 2
In fact
You substituted u=c^1/5
yes
so you replace u with c^1/5 and then solve for c
you get c^1/5 = 2
how would you get rid of 1/5?
@vast shale
I've mentioned it in my solution?
u = 2
c^(1/5) = 2
c^(1/5)^5 = (2)^5
which eliminates the 5 and
c = (2)^5
c = 32
Ok nice job
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how do i know when to use integration by parts vs. u sub? Practicing for a test but then i encountered this: integral (10/(xln(x)))dx
you dont always know before what will work
with some experience you can often have a feeling for which is more likely to work
but sometimes you just have to try a few things
generally speaking of course, ibp is for products and u-sub is when you have a composition of stuff
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i drew possible counter example but idk if i am right or the "right answer" is right
the correct answer is False
How do you determine that Sand is a subset of Tiger
A is a subset of B
Some element of A (and B) is NOT an element of C
Some element of C is not an element of B
All cats are felines
Some cats are not diabetic
Therefore, some diabetics are not felines (True or False)
@fading perch Has your question been resolved?
i assume you can't determine it either way
it means false in that sense, not that all sand is tiger
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This is the question I’m working on
This is my workings so far
the answers are correct but
how can i have tangent line y = 12x -16
and then lower down it has 12h+8
arent they supposed to be the same
because the approximation is the tangent line
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hii
can i get some input as to whether my proof is correct?
(for the converse I already have a solid answer, it's the forward statement I had some trouble with)
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@sinful swan Has your question been resolved?
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how do you solve this
show your work if possible
i got 17sin(beta)=8
sin(beta)?
ah, ok I thought you misread it and did sin(B)
oh no lmao
but its asking for an exact answer
now it's enough to do arcsin(8/17) in your calc
whats arcsin
sin^-1
make sure you're in the degree mod and not radians
yes, if you aren't familiar with it, you can also read the answer from an appropiate table of trig values
yes
it's not possible, because sin is a function, sin(A) doesn't mean sin * A
im pretty new to this mb i just know how to find the "equation" not use a calculator



