#help-27
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Correct
oh so its like that always
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Not sure how to solve this
have you heard of implicit differentiation
No
try writing this as [g(t) = e^{\ln\left(t^{\sec t}\right)}]
maximo
It says I need to solve it with rules
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this table is confusing
i don't think your answer for b is right
is it 2
yep lol
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I need help with this, I need to fix what the student did wrong and give suggestions as well as solve it but Iโm confused
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if you submitted this as a test and got marked wrong on some work somewhere then u deserved that
Given the graph above. $f(x)$ is the third degree polynomial, $g(x)$ is the linear equation
FungusDesu MSC2020 34A05
no lol its homework

anyway
The shaded region's area is $\frac{250}{81}$
FungusDesu MSC2020 34A05
Evaluate $\int_0^1f(x)dx$
FungusDesu MSC2020 34A05
as you can probably tell from the screenshot i tried a lot of ways, but its pretty much deadend
tried a simul equation with 5 var, but can only find 4 equations
@solar goblet Has your question been resolved?
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Hello all! Having a problem with this question, I honestly have no idea where to start simplifying
I've looked for common factors
There isnt any
So i dont know where to begin with this integral
you could try to split the integral into 4 of them, as I believe you can use partial fractions for the latter two terms
You do like f(x)/ x-2 + g(x)/ (x-2)^2
Just split that in the integral and find f(x) g(x)
This precalculus video tutorial provides a basic introduction into partial fraction decomposition. The full version of this video contains plenty of examples and practice problems with repeated linear factors and repeated quadratic factors. Partial fraction decomposition is the process of taking a complex fraction and breaking it into multiple...
i havent used that since like
algebra bro
lemme figure out how to do that LMFAO
fr
basically a way of expressing fractions into simpler, actually integratable terms
and poly division for the first two terms obviously
looks like a disgusting integral all round but hey
ok
2x + (x+1)/x^2-4x+4
is the new integral
makes sense
do i have to do this partial fraction thing now?
yeah
make sure that the other part
I don't think there is one, no?
when you divide you have the whole number thingy
isn't it just (x+1)/(x-2)^2
so like without remainder
my brudda in christ what is da number thingy
LMAO
ok
so when you divide
you get a number
with no denominator
like not the remainder part
ok
ok so i i have to do partial fractions it not going to be on my exam
so i am moving on
lol
ok so for this:
would the final integral be x^2f'(x) - (2xf(x) - 2int(f(x)dx) ?
im just confused because the final protion ends up with f(x) in the integral and idk how we integrate that
oh wait im slow
no im not im confused
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it's 4
the value of the function at x=0 itself does not have any effect on the limit
you only consider x values near zero but not actually at zero
@vernal briar Has your question been resolved?
I see thanks
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if i have an imaginary number (-2i)^n. can i do (-2)^n * (i)^n
is that a valid operation?
yes
(-2i) just means a product of n copies of (-2i)
you can rearrange it since multiplication is commutative
move all the -2's to the left, and all the i's to the right, that gives you (-2)^n (i)^n
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how to solve this
answer is 0
๐
@zinc rover
Use the formula x^logay = y^logax
1st and 3rd terms are same , similarly with 2 and 4, therefore the answer is 0
@zinc rover
many times
yeah dont give out answers
For that explain what is your problem exactly ?
bro u need to tell me where u get these imagex
not mine
oh ok
i am merely the messenger
i tried to do 3^log75-3^log57 first
well it was wrong attempt at first
how can you know or derive that?
,rotate
@zinc rover Has your question been resolved?
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Regarding the formula for volumes using shell method, will r(x) = x and r(y) = y always?
do more problems and find out
I did and they always seem to be equal
it is possible that my prof has given us easier problems
do even more
Can you give me an example problem where r(x) โ x
.close
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i need help with this problem
groovy close your other channel
is fine we clogged it up, our fault
okay
Why people are using these meme recently ๐
cause funny
- its funny as hell
What have you tried so far?
these are the new helper factoids
i have the solution but i dont understand it at all
Could you exhibit it?
wait wat
always have been
at what point did you get lost
do you know where int 0 1 A(y) dy comes from?
ay dy is the volume when calculating volume using cross section method
if thats what ur asking
do you know what that means?
nah
now reread the problem closer
youll notice that you dont really need to care about what the actual 3D shape looks like
you only need to know that:
- the base looks like this triangle
LMFOAOO
- if you slice the 3D shape into slices, each slice has a "base" of the purple strip and is a square like in the upper-right
first of all
there is more than one slice
isnt there
so you cant just calculate the area of one slice and call it a day
do you see the shape's slices
that looks like it has a base of a square no?
okay mtt don't kill me if i'm wrong
but instead of z = f(x, y)
why don't we just set this y = f(x, z) then integrate
the shape is not sideways
never mind then
they were specifically instructed to integrate it this way
oh okay so its laying down rn
to practice a method
you can see that its a pyramid so that gives an alternate way to find the volume to check our answers
shrugs
but really we're here to practice
alr the shape was turned around in the picture though
it should look like this
back:
side:
now imagine you take slices like this
these slices are perpendicular to the y-axis
can you see that the slices are perpendicular to the y-axis
mtt i have one question
yup
I paid attention in class
no no no
i meant with the quick graphing skills
i know how to multidim integrate too
bro's fr a Van Gogh for desmos
ren has not seen actual Van Goghs do this better than I can
bro is easily impressed
then go to https://desmos.com/3d and you can do the same
fr fr
now we can go back to what an integral is
and integral needs a lot of parallel, evenly spaced slices
and its capable of adding them together
right
yup
now lets consider our slices here
first, each slice represents the area of a square
that way, when we add the slices together, we get volume
wait I need to make this look better
those slices need to have thickness
alr here we go
the slices should really look like this
as the slices get thinner, the squares become more accurate to the real volume
do you get these slices
yea
nice
now taking a look at one of the slices,
this slice has a thickness
and also has a length and height
right
yes
yup
now we need to figure out the length and height
for the sake of convenience, we'll instead do A(length)
after all you only need the length to calculate the area
so you figure out the length,
then A(length) will figure out the area of the square given the length
(A(x) = x^2)
does that make sense
yes
so we have the area of the square figured out by doing that
now we just need the length
this is where the method gets looser
notice here that from above, the slices go from 0 to the edge
lets call this length "X"
now we know the y-coordinate, y, of this slice
we also know what x + y = 1 looks like
as shown with this green line
the line can be rewritten as x = 1 - y
since we know that X goes from the left at x=0 to the right at x=1 - y,
the length X must be 1 - y
this might not be what you expected, do you understand this
nop
do you need a few minutes
so idk i think i got shell and disk method down
this is also a separate method
but cross section i just dont understand it
its the 3rd one
yea and its your fault for doing it sleep deprived 3 hours before the midterm
had we done this like 7 hours earlier
i tried way before
had we done this like 7 hours earlier
thats not my fault ๐ญ
bro your midterm was in 4 hours and you chose to ask a question instead of go to sleep
it aint that easy
ik but it was my last hope of understanding cros section cause there will be a cross section question 100%
dont wanna just lose the marks
manage your time and just sleep on this if all youre going to say to "do you want to understand this" is "ngl"
whaaat
your words
bro i appreciate ur help t
i rly do trust
then answer the question
do you want a few more minutes
with a yes/no instead of a ngl this time
bros upset at me
i dont think a couple of minutes will help me understand it id appreciate if ud help me
unless theres nothing else to be saidn ill just keep re reading it
take a look at the y in this picture
I already told you all I needed to say
i understood everything but the last part why re arrange for x
look at where the red length starts and ends
as a horizontal length it represents an x-coordinate
you can see it starts at x = 0 on the left, yes?
yes
yup
the y axis
so what's on the right?
you dont know
so instead
we draw this green line here for the right edge of the shape
we know the equation for this green line
it's x + y = 1
yes?
yes
literally repeated myself there
told you you only needed a few more minutes
we're very close now
because we know the left and right side of this X,
we know how long X is now
the length of the red slice (X) is 1 - y, yes?
yup
yup
and so A(1 - y) dy would be the volume of the red slice, yes?
yup
and so $\int_0^1A(1-y)\dd{y}$ would be the volume of every slice, yes?
mtt07734
yup
then that has to be the whole volume of the shape
its harder to consider at first, but its just like a regular integral but in 3D instead of 2D
so that's how you get $\int_0^1A(1-y)\dd{y}$
mtt07734
from there, you know the area of a square means squaring the length
so $\int_0^1(1-y)^2\dd{y}$
mtt07734
sooo
last question
where does the negative come from again?
is that just chain rule
yea
btw
(1 - y)^2 is the same as (-(y - 1))^2 or (y - 1)^2
you integrate (y - 1)^2, you get (y - 1)^3/3
this is the same answer as -(1 - y)^3/3
since -(1 - y)^3/3 = (-(1 - y))^3/3 = (y - 1)^3/3
what I mean by this is that you can do this integral either way
because even though they might look different theyre not
wait so to integrate a bracket u increase n by 1 put it over n+1 and multiply by the derivative of inside?
no not like this
you divide by the derivative of inside instead
and you need to have nothing except the original after the division
this is reverse chain rule not regular chain rule
since youre integrating (reverse derivative)
ur the only one in the server who helped this hard icl
appreciate it
u mind if i add u and ask questions whenver or is that a no no
ty
usually I dont respond but you can just DM me some questions and I might get back to you
not really that online is all
np and gn
@snow tundra Has your question been resolved?
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guys
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xโ7 = xโ2 + โ32 find the value of x and answer in (a + bโ14) รท 5 form if a , b are integers.
i dont know where to start
did you try solving for x
do i do something like this xโ7 = xโ2 + โ32 x(โ7-โ2) = โ32
and then โ32 / โ7 - โ2
?
rationalize it
i saw this xโ7 = xโ2 + โ32 x(โ7-โ2) = โ32 somewhere but I'm not sure how to get to it
rationlise this
(4โ14 - 7โ2) / 7?
i have a question where did the x go in this
you need to rationlise this to find x
(4โ14 - 7โ2) / 5
oh okayu
you can find a,b by comparing it (4โ14 - 7โ2) / 5 with (a + bโ14) รท 5
ohhh
so after i rationalise that, i just compare it with (a + bโ14) รท 5?
to get a and b
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Is it correct so far?
I've never done a similar exercise where phi is not an integer so it felt like I did something wrong
yeah its good
Ok great! Would you kindly like to explain how I can compute (d) and (e) or just give me some tips? I haven't seen that kind of probability exercise before
use the fact that |X| > 1 is the same as X < -1, X > 1
and why does e seem to be exactly the same as d
So I would need to compute X < -1 and X > 1 separately before coming to a conclusion on that one?
because the X <- 1 and x > 1 holds true for x^2 aswell
yeah
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what have i done wrong here for <-44,20,28>?
Itโs a dot product, not a cross product
if there is $\times$ or $\cdot$ between the vectors
Tushar
!1q
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you can open a new channel
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then got 1/1+x^2
no
tell me how am wrong
i legit told differentiate ur ans
lol
not the question
i will say the integral of 1/(1+x^2) is special i think
why differentiate??
i am using integrals
i mean you might as well, just to sanity check yourself
if you differentiate it and get your original integral, you did it right
he is obvi not
when you're doing integrals you can always check to see if your answer is right if you differentiate the result and get the integral back
ohhhhh
in your case, if you differentiate your result and compare it, you get something else
i wudve expected a guy doing indefinite integration to know that
its also not really a word so
how do i find the antiderivative of 1/x^2+1
yea
this one is a special case
do you know the trig derivatives/integrals
bruh i msut memorize them?
i mean if you're not going to have a cheat sheet on a test then yeah
if you are then id just remember what they look like in general
ah wait no here's a complete one
anyway yeah that's basically it lol
you can .close if ur done
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What's the order of operation for AโฉBโชC? It's clear when (AโฉB)โชC or Aโฉ(BโชC) distributing, but not so much for the other one
intersection first is more likely
I say left to right
So yeah like frownyfrog said its probly intersection first
but i didn't mean left to right
does this imply that if it was AโชBโฉC you'd also do the intersection first?
so far we agree tho, i'd do AโฉB first in the original exercise
sorry, I meant to quote this
it's a guess
what did they mean, whoever wrote it
i would guess intersection first
got you
we're all kinda guessing here then. The other two exercises y mentioned (where you can distribute) follow this one, so it's supposed to make sense i guess
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how do i start this?
A couple of things first:
Var(aX+b) = a^2 Var(X) for any constants a,b
do you get why that is?
because Var(X) = E[ (X-E[X])^2]
yes i understand that
@digital ember Has your question been resolved?
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hI
How can i find all X values in the interval [0, ฯ] that verify the ecuation
I don't know how to solve this kind of problems
what is sen
is sen = sine
sin?
probably, that seems the most reasonable choice
yes
it means multiply
then make sin as an x
it's common writing when you dont have avaliable fancy formatting
and find a x
ye
then solve quadratic
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Help
Pls help with this situation
What question
ok thats correct
but do u see that option b is also true
What exactly dont u understand in it
its a protractor I hope u know that
Wdym
True i think
Mln is 120
One seocnd
Isnt it an acute angle
It's 120
I don't understand
name the angle
It says angle MLN
what is the name of the angle
mln
This
Oh yeah
acute = less than 90
Right angle = 90 degrees
Obtuse = mroe than 90
then if its an **acute angle MLN **how can it be 120 degrees?
MLN looks like acute angle
yeah
But it's 120
Thats the measurement on the protractor
but u have to substract the lower limit from the upper limit
Not 120
yesssirrr
Ohh
180 - 120 = 60
Then why do they confuse us with this
thats how the basic works
Yeah
lemme ask
measure me the angle NLO
30
Right
Yep thanks ๐๐ฝ๐๐ฝ
Nicee
Only B IS CORRECT
Actually u can do it visibly
after a lot of practice
but for beginners
u can write dow the left hand side
with numbers
add
and then count the angle on the right hand side
Ohh
that makes it easier to understna
@full fractal Has your question been resolved?
64x8?
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hi
Whatโs your question?
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Can someone please help me with this
send again, it hasn't been pinned yet.
ummm
so first what is the surface area formula of a sphere
A = 4pi r ^2
alright and whatโs the volume formula?
V=1/3pi r^2h
not quite
yep
Ok
ren
what can we do to each of these formulas to achieve this?
Derive them
with respect to what
dv/dt
with respect to time yes
so if we differentiate both of these formulas what do we get
knowing that dA/dt is 48pi
and the surface area is 36pi
Ok what next
dA/dt = dA/dr * dr/dt
what did you get after differentiating?
you have to use those two equations to solve for dV/dt
What do I derive
4pi r^2
we have to take the derivative of this
with respect to t
which would be?
note that r is changing with respect to time as well
so itโs not a constant
4pi r^2/t
y0shi
what would i get
4pi x
Oh I get it
yep
but if we arenโt differentiating with respect to x
but rather a different variable t
such that x is a function of that variable
we have to apply the chain rule
8pi t
Yea
but due to the chain rule
and r is a function of time
we have to multiply by dr/dt
So what is the derivative of both equations
well so you got the first one which would be $\frac{dA}{dt}=8\pi r\frac{dr}{dt}$
y0shi
yes?
Yea
using the same concept here do the same for the volume formula
12pi r^2/3
yes
and donโt forget to multiply by dr/dt
so since we know that the surface area at the instant of time we are observing is equal to 36pi
what would be the radius
since we have two unknowns currently
dr/dt and r
but we can solve for r using the condition given
$\frac{dV}{dt}=4\pi r^2 \frac{dr}{dt}$
y0shi
yes
so notice how we need to solve for dV/dt
but we have two unknowns
r and dr/dt
using the fact that the surface area is 36pi, what would be r?
6?
How do I find r
so since we know the surface area is 36pi
which equation above relates the surface area to the radius?
dv/dt = 4pi r^2 dr/dt
not exactly
we just have to use the regular surface area formula
A=4 pi r^2
so we can just plug in A for 36pi and solve for r
3
4pi r^3 / 3
uhh not exactly
there isnโt a dr/dt term in that equation
we actually have to use the differentiated surface area formula here
since it gave us the rate of change of surface area
4pi r^2 dr/dt
but using this formula
do we know what dV/dt is?
no right since we are trying to solve for that
No
yep so we have to use the other formula
dA/dt = 8pi r dr/dt
yep
we know that dA/dt is 48pi
and now we know that r is 3
we can just solve for dr/dt here
2
yep
now we just have to plug it into the differentiated volume formula to solve for dV/dt
dV/dt = 4pi r^2 dr/dt
yep
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Can someone help me prove that this sum diverges
what about multiplying by the rational conjugate
I tried taking out n then doing it
$\sqrt{n^2+n+1} - n = \frac{\sqrt{n^2+n+1} - n}{1}$
riemann
can someone explain this....
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so yea how im thinking this problem is going to be about triangle similarity
but im not sure how this quiet works
having 1 same side means what exactly?
solely with line af and line fc i can get bf?
this should be a very easy question to many since its only a grade 9 problem but if anyone does have time please do help me on this
<@&286206848099549185>
,rotate
??
where are the questions
what are the possible areas of the rectangular sections of the wooden wall
well, let's focus on f(x)
f(x)=-floor(-x/4)
floor is just another name for greatest integer function
greatest integer function rounds down to the nearest integer
floor(1.4)=1, floor(-2.2)=-3, floor(2)=2, floor(1.9)=1
we're doing this to give us a range of values for what 'x' could be
i.e. we know 9=-floor(-x/4)
-9=floor(-x/4)
lets say we ignore the floor, and we have -9=-x/4
ok
what would x be?
-1
no...
-36
no, you're closer though
i'm just asking you to solve for x
im confused
is -36.1/4 gonna be bigger or smaller than -9
smaller ofc
right
but uh
im a little confused by your approach
so i think what were tryna find rn is line bf
and to find it simply there is something about triangle similary which is what i dont get
somehow with line af and fc we can get bf
could u elaborte on that part
from my point i see that ac which is the same as ed which is basically the width is 8 as its given now only thing we need is the height
and yea thats the problem for me rn
and right once we get bf we can obv substitude another variable in for the remaining high line ae or cd
but yea the thing is
how do i get bf
ik its smth abt triangle similarity but cannot seem to get it
you can express each of the legs of the right triangle in terms of BF (call it h)
then you can write the area in two different ways