#help-28
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the answer would be ln | 5x - 8 | + c
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js
help..


just to be clear, is that your textbook or your own work?
scheme from my module
given the functions f(x)= 8 + 5x and g(x) = 4/x+2 find (fg)^-1(x)
@vestal meadow
<@&286206848099549185>
Chill
Yeah, I would stop at line 3
And then do the inverse from there
Not sure how they have done that
i think the scheme is just wrong…
Yeah I think so
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Hey guys, I need help with this question:
***A square building site is bounded by the following corners: A(3,2), B(-5,28), C(36,27) and D(38,11). All measurements are in m.
- Calculate the lengths of the 4 sides of the building plot.***
Are there any special formulas I should use?
I have also drawn the square:
Pythagoras' Theorem
Isn’t Pythagoras theorem only used in triangles that have one 90 degree corner?
you can always form a right-angled triangle with the hypotenuse being the side you're interested in
for example, for the line AD, I can form a right-angled triangle like this (horrible drawing I know)
Oh!!
If someone can confirm it would be great, but imo I would solve this by using vectors. On the right side are the formulas
I don't understand the last line
AB?
yes, the line you underlined
I would've asked, but I understand now
😂 ok
So I should just do the same with the other lengths, right?
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I don't know if that's revelant, but have you tried to do +i -i on the numerator? It may help to simplify this division?
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How do I find the integral of this
@royal kiln Has your question been resolved?
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@royal kiln Has your question been resolved?
@royal kiln Has your question been resolved?
Done a ton of integrals but never seen one in this form but I did manage to solve it
First thing I did was try to remove the square root with a u-sub, I couldn't do that but ended up removing the denominator in the root
I set u = x - 3 to do the above
As far as I am concerned i should start with t=(2x+1)/(x-3)
But then it still seems to be kinda hard
I'm not sure how helpful that u-sub is
Re checked my work
I actually did u^2 = x - 3
I guess that's sorta the same as t = x - 3 followed by u = sqrt(t)
You're missing a 2 before your u
And using substitution so many times seemd too complex
2t => 2u^2
It can be daunting but It's fine
After correcting that
Here's the answear
I thought i was clouse but I have no idea how have there appeared 2x^2-5x+4
Because you're not done yet
Which is (x+3)(2x+1)
Could I suggest my next substitution
Right i still have to deal with u^2/sqrt7+u^2)
Of course
Wait, how did you get here?
It is on the photo i have shared
Actually nvm. In the second photo: you have the integral of sqrt(u^2 + 7)
You made a mistake when you subbed back in
You're missing the 2 before u^2
Look back and you'll see
Assuming all that is fine. The substitution is $u = \sqrt{\frac{7}{2}} tan w$
Yeah i see
StrangeQuarkAL
What is tan w ?
Should I do an cotangens with it?
Hmm?
Does tan stands for tangens?
Yes (tangent)
Yes
I am also familiar with tangens
But in my country the short for for this is tg
So I assume it is not that
So I thought you meant tangens and the co function would he handfull
Nat, only co-function
And I hear about sinh
Cosh
But actually never used them
The book i use also never mentioned them so there must be diffrent way
Definetely
there might be a much easier way here
long division inside the radical?
wait never mind that still ends up being messy
I popped it into integral calculator to find other ways
Yeah I Belive the t iquals to the inside of the root seems to be the most reliable idea
Integral calculator did t = the reciprocal of the root
Ah ok, it also does what you suggested
It it smoother than this way
Actually, that's great
Nope not at all
Why great?
Do you know how to decompose fractions
I belive i do
You can express that as $\frac{A}{t^2 - 2} + \frac{Bt^2 + C} {(t^2 - 2)^2}$
Okey I will try
Nah still wrong
StrangeQuarkAL
OK it's right now for sure
What did you change
Added a square to the Bt
Do Bt^2 instead
Okey but how do I know this soulf be this way?
,rotate
You want both products to expand out to give terms of similar degrees(if one contains ax^n, the other should contain bx^n)
Yep
But therw is no solution
It is like it is the same vector or the combinstion the the same vetros
Huh, that's strange
the wolfram solution to this integral is a mess btw
The reference solution is quite messy as well
$\sinh^{-1}$ type messy?
caspar
Not looking very arsinhiny to me
Bruh
Oh yeah I see it. I actually had two options for my second u-sub
u = sqrt(7/2) tan w and u = sqrt(7/2) sinh w
I just assumed regular trig would be easier
Yeah I don't actually know. My decomposition is possibly not often
This is a perplexing integral
This leads you down 4 more partial fraction decompositions
I am about to return tomorow to this one can I DM you then?
You may
It's alright. Get some rest
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If you plug three into the equation for be it shouldn’t equal 3
i figured out that one
tips on the inequality
and its not taking off the equal signs
Plug 12 into the equation for B
i did that already genius how do u think i got the 80.41 figure
80.41 isn’t what you’re supposed to get
Which is why I told you to do it again
I’m just trying to help dude
plugging B=12 returns 80.412
Plugging B = 12 returns 3.26
didnt work
Dammit okay let me try something else
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What's the norm of (1+sqrt5) and why?
An intermediate step to determine if Z[sqrt 5]/(1+sqrt5) is a field
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i have a velocity graph like this. if i want to calculate the total amount of distance traveled from the moment of movement start to end of moment, do i take the integral from 0 to 4 of this graph?
additional information: this is a parabola, the axis of symmetry of the graph is parallel to the y axis
oh wait yeah its correct, i was thinking of something else
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56 = 2 * 2 * 2 * 7
how do you write this
like for example
112 = 2 * 2 * 2 * 2 * 7 = 4^2 * 7
is the first one written as
2^2 * 14?
$$56=2^3(7)$$
Bestower
ohh your asking
2^2 * 14 ig yeah
the only motivation for doing this I can image is so you can say sqrt(56) is 2sqrt(14)
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would someone help me with this
I am really bad at probability
I feel like I would just add the 0.125 and 0.375 and the answer would be 0.5
yes
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whatd you try
in general, multiplication by i corresponds to a 90 degree counterclockwise rotation in the complex plane
I think it is B
Because -2i makes it go up two circle and 90 degree rotation counterclockwise right?
I would say try this
notice B is two circles above
for this since you don't have specific points, you could honestly just eyeball it
like just call z something like -2 + i
you dont have to know anything
you just need to write z = a + ib
figure out if a > 0 or a < 0
same with b
see what happens when you do -2iz
^
a<0
-i is a rotation clockwise
b>0
now what is -2i(a+ib)
a>0 and b<0
i see $-2iz = -2ia -2i^2 b$
so C is answer
jan Niku
dont eyeball it
oh
simplify this
z=a-ib
jan Niku
simplify this
z=a+ib
all u have to know is that 2 will double its magnitude and -i will rotate it 90 degrees clockwise, its pretty simple knowing that.
but what if u dont know that
well u can come to that conclusion quite easily
so let them come to the conclusion
you can also eyeball this by calling z = -2 + i, then (-2i)z = (-2i)(-2+i) = 4i + 2
a rotation by i is 90 degrees anticlockwise so a rotation by i^3 is 270 anticlockwise or rather 90 degrees clockwise
or u could just feed them the answer 
scraxzt dont let me drag u through the whole thing if you just want the trick lol
whatd you get when you simplified
since each option is in a different quadrant, you can just check the signs of a and b like he's suggesting
z=a+ib
you could further do like compare a and b, if you needed to
-2ia-2i^2b
-1
okay
so rewrite this
-2ia+2b
jan Niku
ok
jan Niku
I have to go
okay
But I will come back to this later
sure
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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
integrate
a tip for rate problems
think of it logically
u know the equation
so input every value into it
maybe i’m being stupid
😭😭🙏
Feeling eepy so I'm just gonna leave this here
he’s him
Oh btw for he y = etc. you'd need to graph it and get 3.339 for 0 now gnnn
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i have found values of p0,p1,p2 now how can i prove that they are equal?
what did you get for p0, p1, and p2
my values?
the problem asks you for generic u and w
which means your expressions for p0, p1, and p2 will be in terms of u and w
@zinc turtle Has your question been resolved?
p0=1-u , p1=1-w and p2=2(1-w)
how'd you get this
right, but its asking about the probability that you get 0 heads in total, so both the first and second coins are tails
yes
so surely your probability should depend on both u and w
yes
if $X_1,X_2$ is first and second flip respectively, $p_0=P(X_1=T\cap X_2=T)=P(X_1=T)P(X_2=T)$
yes thats what (1-u)(1-w) is
Bair
thats a lot 🙏🏻
ok, what about the other ones?
what if the first coin is tails and the second is heads
p1=(1-w)u+(1-u)w
p2=u(1-w)
will it be p2=2*u
no, i don't understand where you get these expressions from
what is probability of getting two heads? its the probability that the first is heads and the second is heads
so apply independence
$p_2=P(X_1=H\cap X_2=H)=P(X_1=H)P(X_2=H)$
Bair
what are P(X_1=H) and P(X_2=H)?
what
you are given it
does the problem make sense?
x1 and x2 represent the values of the two coins
read the question wrong
my bad
now i just need to make p0=p1 and p2=p1
and solve the two equations i get
yes
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anybody know how i should do this?
This is a good start
However, you still need to convert $\cos(\sin^{-1}(x))$ and $\sin(\sin^{-1}(x))$ into algebraic expressions
otheol
This can be done by drawing a triangle
how can i do that? They arent giving me specific numbers to work with
If you let $\theta=\sin^{-1}x\implies\sin\theta=x$, then you can figure out the expressions
otheol
yup i undertand that
You can simply let the hypotenuse be 1 and the opposite of the angle be x for simplicity
Since that satisfies the constraints of $\sin\theta=x$
otheol
x^2 + ajd^2 = 1^2?
Indeed
ima give it a try, il lyk how it goes
Alright
thx
No problem
squareroot(1-x^2)
/
1
otheol
= squareroot(1-x^2)
Indeed
Dont forget that your sin is squared as well
I believe so
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Good day to you as well
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hi can anyone help me understand what is logarithmic regression i have no clue
Logarithmic regression is something used to fit a logarithmic curve to a set of data
you assume your data fits some curve y = aln(x) + b
one way to tell if your data fits a logarithmic model is if you make a scatterplot that plots e^x against y, if your result looks linear then a logarithmic model is your go-to
apologies, that should be plotting x against e^y
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hi guys i've just learnt about the harmonic series and i have a question
so 1/k for k=1, ... inf diverges
but 1/k^p for p > 1 converges
for example
1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 +... diverges, but (for p=2) 1 + 1/4 + 1/9 + 1/16 + ... converges
Yes
what's your question?
hold up im formulating my question lol
ok so this
1 + 1/4 + 1/9 + 1/16 + ... is a subsequence of 1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 +...
1 + 1/4 + 1/9 + 1/16 + ... converges, so 1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 +... should also converge by this theorem
what am i getting wrong?
why not?
subsequence is formed by deleting the terms of the original sequence
1 + 1/4 + 1/9 + 1/16 + ... is contained in 1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 +...
it's as if we eliminated 1/2, 1/3, 1/5, 1/6, 1/7, 1/8, 1/10...
oh yeaa maybe it's got to do with the relative positions of the term
hmm im not sure i understand
I might be wrong, but we probably can't delete random terms of a sequence, and call it a subsequence, let A, B, C, D, E... be a sequence, then A, B, C , D is a subsequence because we don't disturb their relative positions but A, C, E is probably not a subsequence
also this definition makes sense because a subsequence that converges, means we can easily deduce that a super sequence (I just made that term up), also converges because the relative positions or order isn't affected
<@&286206848099549185>
okay i think i get it now
so to have a subsequence you need to create a function from the original sequence to the subsequence itself in a certain sense?
i.e. you must have a "rule" on how to choose the terms to eliminate from the original sequence
Yes, the rule is again probably that we shouldn't disturb order or relative positions, sorry for the unsureness, I'm a HS grad and trying to learn as much as possible before college lol
dw you know better than me as a hs grad than me as a university student lol
thanks for the help btw
appreciate it
you're wc
sorry to bother you but in the subsequence i created how are we disturbing the order of the positions?
i mean, if a sequence is in the form a1, a2, a3, a4, ..., an
in order not to disturb the order of the positions a subsequence of a1, a2, a3, a4, ..., an must be like a1, a5, a8, a9, ...
<@&286206848099549185>
Help me to solve this question
in the original sequence we have that a1 comes before a5, a5 comes before a8, and so on... and similarly in the subsequence a1 still comes before a5 and a5 comes before a8
so we're still keeping the order of the elements
similarly in 1, 1/2, 1/3, 1/4, 1/5 ... the subsequence 1, 1/4, 1/9, 1/16... keeps the order of the elements
There are various interpretations of order I think, what I mean by order is "this precedes that", eg: for a sequence a1, a2, a3..., so a sequence like a1, a5, ... here this breaks the rule "this precedes that", also more generally I think, a subsequence is something that preserves the rule of progression of the sequence, this not only does satisfies my definition of "this precedes that" but also guarantees the proposition you mentioned to be true. The rule "this precedes that" is probably a corollary of this definition.
whatever the definition, the proposition is def true, no one writes a false proposition, which guarantees that the definition of a subsequence is not what you had thought
hope this helps!
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try setting two variables for the speed of car and train,
you should get two linear equations
which you can then solve
bruh wtf this is my channel 💀
but yes wrong channel
okay so that "a subsequence preserves the rule of progression of the sequence"
this means that if we have the sequence (n) = 1, 2, 3, 4, 5, ...
it's an arithmetic sequence with common difference 1
and we define a sequence (p) that is characterized by all the prime numbers, so (p) = 2, 3, 5, 7, 11, ... then (p) is not a subsequence of (n) ?
the elements must be equally distanced?
I said it preserves the rule of progression
I didn't say it changes it
so
yes it
is not a valid subsequence
according to me lol
can you elaborate please
so like most sequences are not random, right? Most sequences have a rule of progression, this makes their summation for example, to be written in the capital sigma notation. So, a sequence formed by deleting the terms of the sequence without altering it's rule of progression means another sequence with the same properties as of the original sequence. This makes the proposition that you mentioned guaranteed to be true. Because if the rule of progression is the same, the convergence property of the two sequences must be the same too.
<@&286206848099549185>, where are the helpers lol
but well, in my example (p) has still the same properties as (n)
every prime number is still a number
https://youtu.be/KqX0mKcV_3A?si=_dXZGd0xd7FpmAJa&t=432 this guy says that 1, 1/4, 1/9, ... is a subsequence of 1, 1/2, 1/3, 1/4, ...
What are subsequences in real analysis? In today's lesson we'll define subsequences, and see examples and nonexamples of subsequences. We can learn a lot about a sequence by studying its subsequence, so let's talk about it!
If (a_n) is a sequence, we can denote a subsequence of (a_n) as (a_{n_k}). Here, {n_k} is itself an increasing sequence of...
<@&286206848099549185>
starts here
that's like saying earth follows the same orbit as jupiter because they're both contained of matter, it's not considered a rule of progression, that would make every sequence with numbers subsequences of each other
eh sorry if im dumb
this is so confusing
no lol you're not don't worry
I might have just bullshitted a lot, if this all comes to be wrong lmao
"that would make every sequence with numbers subsequences of each other" 1, 1/4, 1/9, 1/16 is not a subsequence of 1, 2, 3, 4, 5, ... though
the sequence of all prime numbers is of course a subsequence of all (natural) numbers.
mkay
is 1, 1/4, 1/9, 1/16, ... a subsequence of 1, 1/2, 1/3, 1/4, 1/5, 1/6, ... ?
@polar valve
of course.
okay so going back to the original question
.
youre mixing up sequencies and sum of sequencies.
if b_n is a subsequence of a_n, you cant say sum(b_n) is a subsequence of sum(a_n).
but sum(a_n) is defined as lim n->inf (a_n), correct?
no.
if a_n = 1/n then lim a_n = 0 but sum(a_n) does not exist (or is infinity).
so sum of sequence and lim of a sequence are different things.
sorry, what i meant is: if s_n is a partial sum of a series S, then S = lim n->inf (s_n)
thats true.
so a partial sum of S is not a subsequence of S, ok
but dont name the series and the sum of the series with the same letter.
this question doesnt make any sense. a partial sum is a value. and therefore it cant be a (sub)sequence.
yeah right
okay i think i get it now. thank you very much for the help
@subtle hatch thank you for the patience lol
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you might've mistook it for the derivative
but isnt (tan^2(lnx)/x) the same as (sin^(x^2)* 2x ) in that case i know that we make u =x^2 or in the tan case lnx
not in the value the sam but in the integration method
like in sin(x^2 - x + 2) (2x-1)
u = x^2 -x + 2
du = 2x -1 dx
sin(u) 2x-1 (du / 2x-1)
= -cos u + c
so in the case of squared i cant use this method right ?
yeah there are usually trigonometric formulas that can simplify squared functions to make them easier to integrate
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hi :)
okay so i am a bit confused with these
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In both the Massachusetts Number Game and the New Hampshire Lottery, a 4-digit number is drawn each night. On Tuesday night, September 9, 1981, the number 8 092 was drawn in both lotteries. The newspapers block lettered that the probability of both lotteries drawing the same number is only 1 in 100 million. Is this correct?
heksbsheizjejekzkzkzkzkzkzlsnsns
i wanted to do this
answer is 0.01%
so 4 out of 10 possible digits
its not about digits drawn, they draw whole 4-digit numbers
oh
So you just have to know how many 4 digit numbers there are
and then you can calculate the probability
of both drawing the same 4-digit number
think about how u would construct a 4 digit number, u have to pick from 10 numbers for the first digit, then u have to pick from another 10 for the second digit etc...
because what u are working out is the probability of them both getting a specific number
what do u think the probability of 2 people picking the same thing in rock paper scissors is?
🤷♀️
well think
why isnt it just ncr(1,1)^2/ncr(3,1)^2
that equates to 1/9
i can see what you're thinking
lets say the first guy picked rock, thats a 1/3 chance of him picking rock and 1/3 chance of the 2nd guy picking rock meaning there is a 1/9 chance of them both picking rock
but that doesnt help us work out the probability of them picking the same thing
because what if they both picked scissors? or what if they both picked paper?
here you know the first one picked rock and that was 1/3 and so the other one has a 1/3 chance to also get rock for it to be the same therefore itll be 1/9
right
so shouldnt the same logic should apply to my problem when you already know they will pick 8092
because why are you viewing other possibilities for them to get the same number when you know its one
But it was about the probability that they both draw the same number not that they both specifically draw 8092
this
If it was about the probability that they both draw 8092 you would be right with 1 in 100 million
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hi guys
I don't understand that
so first it says
This integration can be more easily solved by x = tan∅
english pls
So if if speak of the step
if if?

it says:
Let's define a new variable u implicitly with the expression:
...
From this relation, we can explicitly express both u and x to obtain:
...
Or u² = 2(x² + x√x²+1) +1
yes keep making a mess by squaring
,, u - x = \s{x^2 + 1} \Implies (u - x)^2 = x^2 + 1
one then easily concludes the desired equality
oh alright so x has to be alone?
I will suggest solving this by considering x = tan∅ though
yeah but thats not what im studying
Yeah
that
it says that for integrals of that type we can always by universal substitution to
translate the integral to a integral of a rational function. When choosing the new variable u, we distinguish two
examples:
and then those two above
anyways thank you @low echo , @topaz valley for taking the time
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hello
please
does anybody have any advice on how i can master trig triples
ive looked for questions
and i cant find any
umm by trig triples, do you mean Pythagorean triples?
triple angle identities?
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its more of an understanding questino really but it uses triangle similarity and optics
i have a solution i want checked
am asked to find the area of the shadow casted on the screen.
though wont the area of the shadow be the entire trapezoid formed by area A?
my question is, is the area of the shadow cased on the screen the area of A? (the trapezoid) or only the length of the dark part on the screen?
- here is the original question - suppose a Point light source that is located 4cm away from an obstacle (a side of a square) which its length is 6 cm. from Point light source we also set a screen located 8 cm away from it as the Point light source is located in front of the middle of the obstacle and the same length away from each other ( distance between the light source to the obstacle is equal to the distance between the obstacle to the screen = 4 cm). *
find the area of the shadow that is created on the screen
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@cunning storm Has your question been resolved?
I agree with your solution @cunning storm
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i know trapezium method
and i assume you use the disk method for volume
but what do they mean by that integral?
f(y) dy
this one
isnt that just integrade the curve?
and get the volume kind of
wheres the work
wait
@ancient wyvern Has your question been resolved?
You need to make f(y).
since you're rotating the graph around the y axis, you have to integrate it with respect to y
@ancient wyvern Has your question been resolved?
huh?
yeah?
but dont i need like
the radius
smth like this
so the r value is x^2 no?
oh wait
yeah i integrate y
No. f(y) is in terms of y.
ok
so like
y(y-4)?
for work?
since x^2 sub in 2 you get 4
wait no
its 4-y
Let's step back for a moment and consider what you are trying to calculate. What is the equation for Work?
mass* grav*height
oh yeah include grav and mass
the density
well its there in final so its basically there
But what is the actual equation?
W = F*d
So you need to find a way to evaluate this in terms of y.
W = F(y)*d(y)
Which you will then approximate with the Trapezoidal Rule.
oh
So you need to make an equation for the Force and an equation for the distance.
What is the physics equation for Force?
density * volume
Ok, to find the mass, you need to know the density as well as the volume. This is where the y=x^2 comes into play.
not shell
disk
ok so at a certain y
i need the radius theres
which is sqrt(y)
and formula is pi(r^2)
so it becomes integral of pi(y) for the volume
then the distance is (4-y)
distance from top
so integral of pi * g * density *(y)(4-y)
i think this is correct
Be aware that you are moving disks of the paraboloid upwards. How would you calculate the volume of each of those disks?
How would youl calculate the volume of that slice?
But it needs to be in terms of y.
y = x^2
x= sqrt(y)
Oh yeah. 🙂
nice
So you have an expression for the volume, y*pi dy.
yeah
And you found the expression for the distance.
Put that all together with the density and you will have made your integral.
this right
From that integral, you can make your Trapezoidal approximation.
Yes.
pig density 😄
1/2 ( 1 22 1)
that correct?
trapezoid
ignore the 1 4 2 1 i was thinking of simpsons
The 1/2 isn't correct. (b-a)/2 iirc.
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Please don't occupy multiple help channels.
Can you explain this
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Hi I need help
just post your question
How to do this question 5
we know double digit numbers begin from 10 and end at 99
😂
Question 6)How do I find it
which grade r u?
8
What abt question7 how do I solve this
Yes I know
nah u dont need those for this question
u have to take lcm for this sum if im not wrong
😑
for 8 9 10
yeah then find the prime factors of the lcm
LCM is 360
yes but
Is it correct
Yes
Wait let me do
now u multiply the lcm with 10
u write down the factors
u get
2x2x3x3x2x5
now group them
(2x2)
(3x3)
2 and 5 is unpaired prime factors
they are not perfect sqares are they?
No
yeah so u multiply them
nahuh
wait
lemme clear it for u
2x2x3x3x2x5
group them
2x2
3x3
2 and 5 is left
what do u do to make these perfect squares?
multiply 2 by 2 to get 2x2
and multiply 5 by 5 to get 5x5
correct?
Yes
yeah so
the factors
2x2x3x3x2x5 is the lcm u found
now to make it a perfect square
u multiple another set of 2 and 5
so it becomes 2x2x3x3x2x2x5x5
correct?
360
what root of 3600?
I have sent friend request to you
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i joined this server to get calculus help lmao ended up doing 8th grade work 💀
