#help-28
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How?
ctrl + c, ctrl + v
Thas crazy

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Hello, good afternoon, I need help with this combinatorics exercise please. I don't know how to approach the exercises.
Ex.20) The elevator of a building carries 10 passengers and can stop at any of the 12 floors of the building.
a) Distinguishing between people:
- In how many ways if on the 10th floor exactly 3 people descend?
- In how many ways if at most one passenger descends on each floor?
b) If no distinction were made between people, what would be the answers to the questions posed in a?
@little fractal Has your question been resolved?
Have you tried anything?
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So what is standard form?
standard form not from
Typo
yeah
The question stands
yeah I'm just confused on the completing the square part
do you have any try?
yeah I got down to the x side equals: x^2-6x+9, and the y side equals: y^2+30+225
I just don't know how to simplify it down further
(x-3)^2 ?
wouldn't it be -222-9 because we move the 222 to the right side
I didnt move anything yet
oh okay
what do you mean like (y+15)^2 ?
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7 over x+10
no, you solve it like other exponential problems
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What is the parallel and perpendicular equation of y=1/2x-6
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Hi, so honestly i don't know how to solve this question, could someone help me with this one?
The y coordinate of a point is 2, find the x coordinate of the point if the distance of the point a(1,3) is the root of 16
i don't get it, i mean. why is (x,2)? besides. the coordinate of the point is the root of 16
oh, and it is 2 because the y coordinate of it is 2
once i solve the formula i'll get a quadratic?
yes bro
tysm
i know i have to, i just want to see if i can solve it first since i'm insecure about my answers
is that okay?
or do you want me to close it anyways?
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Where is the mistake here?
But when we solve quadratic equations, we say that both the solutions are correct
±any number ≥0 is impossible (other than any number=0)
"or" states that if any of the statement is correct than the argument is true
My english was not enough there oof
I did not quite get your point
only one of x - y >= 0, y - x >= 0 need to be true
not simultaneously both
the mistake is assuming both are simultaneously true
Assume he have 2 statements p and q and
r ≡ p V q
Yes I thought of your point, but as I said earlier, when we take x² = 25, both x=5 and x=-5 are correct simultaneously, right?
x=5 OR x=-5
will satisfy the equation
x can't simultaneously hold two different values
also the +- in that first step is inappropriate
The square root function only returns nonnegative values
As the degree is 2, I have taken +-, is this wrong?
Then where does it come from in case of quadratic equations?
It comes from x^2-a^2=(x-a)(x+a)
If you have x^2=a^2, you write (x-a)(x+a)=0, so x=a OR x=-a
x=a or x=-a doesnt comes from applying sqrt to both sides and saying x=±a because √a^2=±a
using $x^2 = 25$ as the example, taking the square root of both sides
$$\sqrt{x^2} =\sqrt{25}$$
$$\underbrace{|x|}_{\text{not } x} = 5$$
and casework / definition of absolute value from there leads to $x = \pm 5$
ℝαμΩℕωⅤ
But as the degree is 2 in case of my question, shouldn't it have 2 solutions as I have written?
there'll be 2.5 cases
the point is applying square roots will give
$$\sqrt{(x-y)^2} \ge 0$$
there is no $\pm$ generated here
ℝαμΩℕωⅤ
from the square root property, that leads to
$$|x-y| \ge 0$$
ℝαμΩℕωⅤ
and THAT leads to \
$x - y \ge 0$\
OR $-(x -y) > 0 \to x - y < 0$
ℝαμΩℕωⅤ
So, my mistake was in assuming both the conclusions simultaneously, right?
and technically there's more stuff behind that as well when doing casework, esp for more complex examples
@barren jolt Has your question been resolved?
Here you have said that x-y>=0 or -(x-y) > 0
So, x-y>=0 or y-x>0
So, can't I say x = y?
you can
But then it comes back to the same thing
i attached the equality case to the greater than case for simplicity
you can keep that separate if you wish
The +- one?
and the conflation of OR and AND
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how do I find this angle?
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Could anyone help out with this? Ty
Your approach?
If I could forget everything and started again, I wouldn't want someone else telling me the solution for it
Its one of those problems
😓
I'm confused to the point where I have no clue where to begin 😭😭
Do you know the sum of roots?
Yeah -b/a
So how much in this case?
If alpha + beta + gamma = S, then alpha + beta = S - gamma
^^ This is HINT 1
Okay so alpha+ beta would be -6 - gamma here then
S is 6 not -6 here
Oh yep right -b
Okay yeah
Can you proceed from here?
The denominators replaced
Let me give it a shot
Yup
@torn jolt Has your question been resolved?
Nope couldn't proceed
Were you able to simplify the expression?
I don't think so im pretty much still stuck at the exact same place (forgive my stupidity)
No issues
So beta + gamma - 4 = 2 - alpha
And similarly for the other 2
So the first term in the expression can be written as $(2-\alpha)^3$, do you see this?
Yep did that bit
fukwerint
Ohhh yeah
So you now need to find $(2-\alpha)^3 + (2-\beta)^3 + (2-\gamma)^3$
fukwerint
Now put $y = (2-x)$ in the original equation and simplify
fukwerint
Tell me what you get
I don't get this bit
So if you put y = (2-x)
And simplify the equation
You would get a new equation
If $\alpha$ is the root of the original equation, now $2-\alpha$ would be the root of the new equation
fukwerint
Original equation refers to the f(x)=x^3... Bit right?
fukwerint
Yeah
Now suppose you put $y = 2 - x$, and you simplify
fukwerint
And you get some polynomial in y, say $g(y) = 0$
fukwerint
Where's y tho
You created $y$, namely, $y = 2-x$
fukwerint
Ah okay
I understand y=2-x I'm struggling to understand what a new polynomial with p(y) would look like
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✅
Ohh wait I think I got it
You need to expand the new polynomial
It would look like a cubic polynomial with different coefficients
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this is statistics - Hypothesis testing with T statistics where n<30 and std deviation of population is unknown. When you are finding out whether or not to discard the H_0 hypothesis you are supposed to use T statistics here, like finding out the critical value by using T table, my question is: if you are given a confidence level to test for discarding H_0, and its a one tailed test for the right side (i think this is irrelevant but idk) Are you not supposed to divide the alpha by 2 in this case? since its T distribution.
@cunning bronze Has your question been resolved?
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in solving this triple integral, why is z between -arctan and arctan
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I am stuck on the spearman coefficeinet question
After ranking all the the numbers from biggest to smallest i got
isnt that just a 🔌question
yeah the answer was supposed to be like
0.9554 and i keep getting 1.04
i was so confused and i though my ranking was wrong
let me look at your working out
You shouldn't have a rank of 5 there
Because the 4.5 covers 4 and 5 so your next rank should be 6
It's okie lol let me know if you get the right answer
Nwsss
yeah i got it
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How do I do question 7
I set up the integral $$\int^b_1f(x)dx = \sqrt{b^2-1}-\sqrt{2}$$
Nathan
That’s all I have so far
by the FTC, if the antiderivative of f(x) is F(x), then this integral becomes F(b) - F(1)
I wrote that too but I’m stuck there aswell
Yeah but I can’t quite figure out F(x) looking at it
see that it exactly matches with √(b² -1)
I thought $$\sqrt{x^2-1}$$
Nathan
But that won’t work for the other one
so if F(b) = √(b² - 1), then F(x) = √(x² - 1) by straightforward substitution
oh wait you’re right
Yeah
That was my roadblock
so F(x) = √(x² + 1)
which you can differentiate to find f
yes
Nathan
yeah
Alright thanks
happy to help
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kisnar
Please don't occupy multiple help channels.
3 integrals, of what?
separate how exactly
if you are referring to 1/x, 1/2sqrtx and 1/2, no its wrong
no, you can't split fractions like that
yes, its wrong
if you're actually trying to solve this, the sqrtx is a little annoying so maybe try letting u = sqrtx
This is question ?
then the integrand becomes 1/(u^2 + 2u + 2) and the differential becomes:
u = sqrtx
du = 1/(2sqrtx) dx
dx = 2sqrtx du = 2u du
so your integral becomes the integral of 2u/(u^2 + 2u + 2) du
If you ever see sqrt(x) in an integral, consider the substitution u=sqrt(x), because sqrt(x) is contained in its own derivative
Basically 1/((√x+1)² +1)
now this is something you can probably evaluate, doesn't look like the denominator factors nicely for you to use partial fractions but the denominator also looks like (u + 1)^2 + 1
which might be useful
you factored u^2 + 2u + 2?
Hm
oh you mean you did the second integral using partial fractions
yeah that makes sense
i'm talking about this first intgeral after you do the u sub
kisnar
you get this
i'll save you the trouble but you won't really be able to nicely factor it
unless you feel like doing partial fractions with complex roots
but i do notice that 2u / (u^2 + 2u +2) = 2u / ((u+1)^2 + 1)
This one is very easy
and if you let w = u + 1, then u = w - 1, then you get 2(w-1)/(w^2 + 1) dw as your integral
when you split this into two fractions by separating the terms in the numerator, the first integral can be done with another substitution and the second integral can be solved using arctan
The factor theorem states that a polynomial of any degree can be reduced to quadratics and linear factors with real coefficients
No i mean partial fractions work for any degree polynomial
when you're writing the form of the partial fractions, you separate based on the factors of the denominator, the numerator is always some arbitrary polynomial that's one degree less than that factor
its actually not , coz you can generalise it
so if i have an irreducible quadratic factor, the numerator will be an arbitrary linear term
you also build up the power in the denominator for repeated roots
that's pretty much the main rules
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@dense turret Has your question been resolved?
The answer is C. Range is the same when the angles of projection are complementary. There is a formula to calculate range. Try to prove it yourself. Also, range is the greatest when angle of projection is 45 degrees if I remember correctly.
Also the speed must be the same when the projectile is thrown
That is already there in the question so yeah
Range = v^2 sin(2θ)/g
Time = 2vsin(θ)/g
where v is speed at which the object is thrown
and θ is the angle
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This is not something you should post here ig
Imma choose China
what the fuck is going on in here
curry rice goes hard
India not having briyani is a crime
@torn jolt Has your question been resolved?
i would have thought tikka masala or butter chicken would be the india stereotype
I mean kichidi is alright ig
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If two players are playing scrabble, and they are drawing their 7 tiles each from the bag of 100 tiles. As long as the tiles remain unknown to both players, than they will always both have equal odds to pull any given tile..................in other words, wether my opponent selects his 7 tiles, followed by me selecting my 7 tiles, OR.....my opponent selecting 1 tile, followed by me selecting 1 tile, until we each select 7 tiles each.....no matter which of these "draw" methods you chose, both players have equal chance to draw any 1 specific tile..............Even tho in the first example, the second player would be drawing from a pool of 93 tiles opposed to the initial drawer, drawing from a pool of 100 tiles, because the draws themselves remained unknown until the conclusion of the whole process, the probability for drawing a specific tile remains the same for both players..........my question is simply......would Bayesian inference suggest the same thing I just said? Or would Bayesian inference suggest if I draw second, after my opponent has drawn his 7 tiles, my odds cannot be the same as his, because even tho we don't know which specific tiles he has, we know the number, and that by definition changes my odds.
@hollow helm Has your question been resolved?
No it's 5:54 in the morning and I'm asking dumb questions sbout Bayesian inference related to scrabble
Who would possible be up at this hour to answer such a dumb question
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whats your question?
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is an eigenspace just the set of all eigenvectors for a given matrix?
this is what my lecture notes says but im tryna wrap my head round this ahaha
Eigenspace is the set of all vectors that satisfy the equation
Its a vector space
Suppose it has 2 vectors, v1 and v2
So you know $Tv_1 = \lambda v_1$ and $Tv_2 = \lambda v_2$
right
fukwerint
So you know that $T(av_1 + bv_2) = \lambda(av_1 + bv_2)$ also
fukwerint
im just confused because I thought that each eigenvalue has a eigenvector to go with it, is the eigenspace not just the set of all eigenvectors?
For any a and b
Each eigenvalue may have multiple eigenvectors
So if the set you are talking about contains $v_1$ and $v_2$, it would also contain all vectors of the form $av_1 + bv_2$
fukwerint
Tell me if you have any issues
hmmm i see, im just trying to look at a worked example we did in class also as well as reading this
Whats the confusion you have
oh wait i think I understand now, so if I have a eigenvalue = 2, then the eigenspace is all the vectors that are Tv = 2v or is this wrong?
ah right got ya
Eigenspace "associated with that eigenvalue"
I was looking at this example and had no idea what was going on till now ahahaha
can an eigenspace has more than 1 thing in it? so you see here we have (z,0,z). could it have another vector in there too?
(z,0,z) means infinite vectors
(1,0,1), (2.1,0,2.1), (2.5,0,2.5), ...all the vectors are in there
ah okok, can i just ask as well what does the span thing mean?
i am unsure on this too, trying to study and learn new content while revision for exams at the same time is tough. not really grasped this content as well as i wouldve liked
Span is defined for a set of vectors
Suppose you have a set of vectors (it may have finite or infinite vectors)
Then the span(that set of vectors) is another set of vectors, which contains all the *linear combinations" of those vectors
By linear combination of vectors, I mean:
2v1 + 5v2 + 7v3 is a linear combination of v1,v2,v3
so for this case here if span = {(1,0,1)}, we say that (1,0,1) is the span because we have the eigenspace as (z,0,z) and so we can write allthe eigenspace vectors as (1 * z, 0, 1 * z)?
i feel like ive worded this awfully i apologise
so say like if the eigenspace was (2z, 0, z) would the span be (2, 0, 1) ?
Its like span(a set of vectors) = another set of vectors
So suppose span({1,0,1}) would be (the set of) all vectors of the form k * (1,0,1) where k is a real number
so in this example here would you say k = z to get all the vectors in the eigenspace?
ohhhh wait i think iam understanding now actually
An easy example would be to see that the span of the canonical 3d basis vectors is all of R^3
Because any vector in R^3 can be described as a linear combination of the basis vectors {(1,0,0), (0,1,0), (0,0,1)}
@wintry hatch Has your question been resolved?
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Suppose that a company's production Q, as a function of the amounts of capital K invested and labor L employed, is given by the Cobb-Douglas production function
Q: RxR→R: (K, L)-> K^2/3 L^1/3
What is the minimum amount that the company must spend on capital and labor to achieve output q if a unit of capital costs k euros and a unit of labor costs l euros? This amount will of course depend on the numbers q, k and , which we assume are strictly positive
So this is the problem I was doing
It was going pretty well but I don’t know how to solve the equations at the end of the page
How do I find the critical point L,K ,lambda
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Need help with question i
Question 2?
Three cylinders like this
Max efficiency !
Now we need to know radii of circle for proceeding
Also idk if three cylinders have equal diameter !
@pulsar mortar hii
@pulsar mortar Has your question been resolved?
Oh sorry I was afk
I’ll get you question 2 now
The three circles have equal diameters
The height of the cylinder is 19.95 I think
When your explaining could you do it in the simplest terms
My teacher hasn’t taught us any of this so I’m really lost on what to do
Ok so
Circle diameter is 6.65 cm
We need to find the side of this equilateral triangle
This is a upper view of our setup
We re just viewing it from top to make work easy
Yeah !
Ok
Yes
We can get the value of x using trigo
Total length of a side will be 2x + 2r
So can you calculate?
no
You see length of one side is approx 11.52
Ya
Area of equilateral triangle give by
√3/4 a²
So area = √3/4 (√3×6.65)²
Area × Height will yeild the volume
,w √3/4*(√3×6.65)²
Result:
19.95
Result:
1146.1275
So its 1146.1275 (approx) cm³
surface area = 2×triangle area + 3×height × side length
,calc 257.45+319.95*11.52
Result:
804.372
So approx surface area = 804.372 sq cm
I gotta go sleep but could you just explain what question 3 i is asking me to do ?
Its asking you to calculate the total surface area of the prism
That i have already explained and calculated
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Have I started of this integration by substitution question correctly ?
whats that 2sincos(1/2x)
Bro
then you still need to apply chain rule
Why didnt you split it
Ignore the cos that’s there by mistake lol
We haven’t learned that yet, my teacher has just told us to do substitution
Integration of cosec²x/2 is -2cotx/2
what
You can atleast use your logic of algebra
How so ?
^
Oh so rewrite as respective trig identities and integrate those parts ?
That makes a lot more sense, thanks for your help
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Hello, I have pretty complicated mathematical problem to solve. Here are the details:
There is a machine that generates 5000 units at a frequency of 57.8(703) mHz.
Every 35000 cycles, 4% of current number of units is taken away and stored separately in a cache.
Provide this cache value after 2^28 seconds.
So far I solved it for 2^21 seconds. The result is 8178,24 units.
The idea is to figure out that 5000 units are generated every day. Since generation can be considered as a event or cycle in the theory of frequency, it means that 1 unit = 1 cycle.
Based on that it's known that every 7 days 4% of current sum of units is stored in a cache.
After first 7 days we have 1400 units stored (C) and 33600 left (G) (C = 5000 * 7 * 0.04 = 1400, G = 7 * 5000 - C = 33600)
After 14 days we have 1400+2744 units stored (C = (G + 5000 * 7) * 0.04 = 2744, G = G + 7 * 5000 - C = 65856)
After 21 days we have 1400+2744+4034.24 units stored (C = (G + 5000 * 7) * 0.04 = 4034.24, G = G + 7 * 5000 - C = 96821.76)
After 2^21 seconds nothing more is stored in a cache because it's before day 28 so the result is 1400 + 2744 + 4034.24 = 8178.24 units
2^28 seconds means that I pretty much can't do it this way and I have to create a formula.
Please help.
do you know the answer
no
I'm almost sure it's wrong. The formula was pretty complex. I spent like 2 moths making it 10 years ago but it's lost 😄
@slow rover Has your question been resolved?
@slow rover Has your question been resolved?
It's very easy to solve it using any programming language.
Very hard to create a math formula which might provide performance boost in calculations of very high numbers.
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Hey, so I've just been introduced to how the imaginary plane is at a 90deg angle from the real plane. i also know that imaginary numbers have a period of 4 when to exponents. This results in us having the following number line, from which we can make a circle. My question is, is it possible to deduce the equation for this circle?
and if so, what is it
I think you mean the imaginary axis is at 90 degrees to the real one
The two axes and the plane resulting is the complex plane
yes, the imaginary axis. is there a difference between the imaginary plane and the imaginary axis?
Anyways all that aside
Yeah
Imaginary "plane" doesn't really mean anything
we call the whole plane the complex plane
ah right, i get it
do you know what the modulus of a complex number is
its an application of the pythaogrean theorem, so we're finding the hypotenuse, which would also be the radius
OHHHHH
👀
so we have our radius, and we just need the coordinate for the center of our circle
Which is...
which in this is the origin
Yay
so its just x^2 + y^2 = |z|
how would I go about finding |z| here though? I dont know what my complex number is
or is this the maximum i can go
1+i could be the complex number, but so could -1 -i
well you know a point on the circle
wait, those would be the same if i take the modulus
neither of these lie on the circle
is it not?
Oh right, I cant assume the x coordinate
because its on the imaginary axis
Yeah
not a regular cartesian graph
real part is 0
ahhhh right
it is actually
just the y coordinate is imgainary
and x coordinate is real
so i is just (0, 1)
yea, what i meant by that is that it has a bit more nuance than what im used to
not sure i get what you mean by this
If you overlay a regular xy plane on top of the complex plane
i and the point (0, 1) occupy the same space
I think I get it, would it be possible for you to draw a diagram please? I'm trying to doing so myself but not really sure where to start 😅
Your diagram is right
It's just that on the y axis you can't have the real part be 1
oh wait, i get it
I suggest you check out a video by Khan Academy on complex numbers, it would really help you
i misread (0,1) as (1,0), my bad
Ah
so z = a + bi
since im not moving horizontally at all, a = 0
I am moving 1 unit up, so b = 1 right?
yep
in which case z = 0 + 1i.
the modulus of which would just be 1
so the circle equation would just be x^2 + y^2 = 1? same as the regular unit circle?
yes
ah, thats a little underwhelming, but makes sense
on the complex plane the equation would simply be |z| = 1
was really hoping for something that looked a bit cooler, but oh well
reality is dissapointing
makes sense, thanks!
Yea, that should be it, appreciate the help, thanks again!
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domain of: $\frac{\sqrt{x-1}}{x^2-4}$
Kondor
Kondor
$x^2\neq4$
Kondor
$x\neq2$
Kondor
then the root must be $\geq0$
Kondor
thats not all, what about -2?
$x\geq1$
Kondor
$x\neq2 \ \ \ x\geq1$
Kondor
-2 what?
(-2)^2 = 4
from x^2 not equal 4 you get x nt equal 2 oder -2
I did it without brackets
yeah and when you substitute things you put brackets
why?
thankfully -2 is >= 1 so you dont need to specify it not being equal to -2
it seems Ok to me
So what is the domain?
this
so $x \in$
alee
$x\in (x\geq1 \ \ \ x\neq2)$
Kondor
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For ex. 16, they want to know which values of a,b and c make the linear image sujrective
Now i do not have a clue becaude normally i would day that de dim(Im) = dim(codomain), but since i don’t know what the codomain is i’m wondering how to solve this
can you translate exactly what it says
Well
V and W are vectorspaces with α a basis for V and β a basis for W. The linear image is given by (see matrix). Wat values do a, b and c need to be so that L becomes surjective
The matrix has to be consistent for it to be surjective
i.e. you can't row reduce to a row of zeroes
i do understand your example but what do u mean by 'being consisten' (we prob use other terminology in dutch)
Basically, when you row reduce it with a vector you're trying to map to, you don't end up with something like
0 0 0 | x
Because then there is no way to get x
but why is this?
Say the matrix is
$\begin{bmatrix}
1 & 0 & 0 \
0 & 1 & 0 \
0 & 0 & 0 \
\end{bmatrix}$.
Then there is no vector that maps to $\begin{bmatrix} 0 \ 0 \ 1 \ \end{bmatrix}$.
Ari
Also, the operator is surjective if and only if the determinant is not 0
i don't think that's even a proposition, lemma or a theorem in my book
how would i be supposed to know this?
So $\det(A)=0 \iff A$ is not invertible.
Ari
And since $A$ is an operator, $A$ is invertible $\iff A$ is surjective.
Ari
And we know this by rank nullity theorem. A is invertible only if the null space is trivial, which would imply the range is the entire space
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So I found the derivative and found that the slope was 42 at x = 7.
Then solved for the scalar to be 400/sqrt(1813) that it gave me from the equation below.
I dont see how it's wrong at this point honestly.
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Can someone explain algebra to me? I need to know it for my examens and i'm a 7th grader. I don't understand anything from it.
Ow wait im gonna take my test where i got 40% 💀
Or ask in #prealg-and-algebra
2/7 X= 10/7
,,\frac{2}{7}x = \frac{10}{7}?
𝔸dωn𝓲²s
monkey
why?
word
why do u have the undergraduate math role if ure a 7th grader lol
you can start by sending the 2/7 to the other side to isolate x
what does that mean?
so 2/7 X=
undergraduate is when ure in university
what
is this what u need help with?
yes?
what have you tried
X= 2/7 divided by 10/7 X= 2/7 times 7/10 X= 14/70 or 2/10
pls dont use that format and your wrong
also this is almost correct
$$\frac{2}{7} \cdot x=\frac{10}{7}$$
send the $\frac{2}{7}$ to the other side
$$x=\frac{\frac{10}{7}}{\frac{2}{7}}$$
we can simplify to
$$x=\frac{10}{7} \cdot \frac{7}{2}$$
whoops sorry typo
yes
i mean you have to simplify it first
but yeah you will get the correct answer if you continue it
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Could someone check my work here?
I'm just a little sussed out by the fact that the answer is zero
Feel like I did something wrong
Ping me if you respond pls thanks
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bump
you’ll be better off asking in #multivariable-calculus maybe for visibility purposes/get it seen by people who like mv calc. if i see this tomorrow i might answer but i am too tired tonight
not to say that i don’t like mv calc
i'll try that thanks
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I need help with this exact Question and two other ones. Here the first one: How old is the mother? Today she is 3 times as old as her daughter. 5 years ago she was 5 times her age.*
Well
start with introducing variables to represent their current ages
Yes
So D for Daughter and M for Mother
try setting up equations for each statement, starting with
Today she is 3 times as old as her daughter
So M = T•3
I mean D, sorry I was in German xD
now try
5 years ago she was 5 times her age.*
M-5=(D-5)•5 right?
yes
you now have a system of equations, simplify/solve that with your preferred method of substitution or elimination
For example?
example of what
Of how to solve this problem with my equations
look up system of equations
Should I watch this video
yes
My teacher wants it like this( just replace the t with d)
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A boat can travel at a speed 20 km/h
h = (constant in magnitude) sailing in
calm water. The boat is traveling upstream. The current velocity of the
river is 5 km/h
The desired navigation route makes an angle of 60° with the perpendicular to the
bank of the river.
At what angle θ, measured relative to the bank, must the boat travel in order to follow the
desired cruising route.
Please don't occupy multiple help channels.
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I'm not sure how to start these kind of questions
so do i subsititute values from the graph for this?
yep, basically
what's f(-2)?
read it from the graph
is it 0?
correct
so g(f(f(-2))) is just g(f(0))
because f(-2) is 0
so now you need to find f(0)
will this be 8?
f(0), not g(0)
I'd suppose that it's exactly 6
oo okk
or close to 6
now i subtitute in g(6)?
we care just about the integer part anyway
correct
yes, i think so
thank youu!!
np
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I've moved the terms to one side to get 6x^2-7xy-20y^2=0
I'm not quite sure how to factorise this
no need to factorize anything
divide everything by x^2
also, its -20y^2
so root it??
oh ye sorry!
i did use the quadratic formula to get x as 5/2 and -4/3
since its bigger than 0 can i substitute 5/2 in the eq to find y?
x?
hmm
how can you get specific value for x 🤔
note that youre finding just the ratio x/y
and you have 6x^2 = 7xy + 20y^2
try dividing everything by y^2
so 6= sqrt 7xy+20 ??
why sqrt?
7xy / y^2 = 7x/y
$\frac{6x^{2}}{y^{2}}=\frac{7xy+20y^{2}}{y^{2}}$
MethIsAlwaysRight
nope
$6\left(\frac{x}{y}\right)^{2}-7\left(\frac{x}{y}\right)-20=0$
familiar?
MethIsAlwaysRight
OOO its in the quadratic formm
yep
now you can solve for (x/y)
and thats essentially what youre finding the whole time
thank youu!!
np
well depends on what exaclty do they mean
x/y = 5/2
But yes
probably enter 5 : 2
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what is the limit as x approaches 0 of $\frac{sin(3x)}{x}$
Skill_Issue
try multiplying and dividing by 3
$\lim_{x\rightarrow0}3\left(\frac{\sin\left(3x\right)}{3x}\right)$
ƒ(Why am. I here)=I don't Know
how do i find that?
do you know subsitution in limits?
yes
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yes?
$\lim_{x\rightarrow0}\frac{x}{\tan(2x)}$
Skill_Issue
um do you know d l hopital rules?
no need l'hopital
like the differentiate thing?
yeah?
$\lim_{x\rightarrow0}\left(\frac{1}{2\frac{\tan\left(2x\right)}{2x}}\right)$
ƒ(Why am. I here)=I don't Know
I think so
depends in the region, I guess
you can convert it down to get sin(x)/x again
oh yeah true
subsitute tan(2x) with sin2x/cos2x
$\lim_{x\rightarrow\inf ^{\plus}}\sqrt{x^2-5x}-\sqrt{x^2-3}$
Skill_Issue
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oh yeah i got it
you can multiply and divide this with (sqrt(x^2-5x)+sqrt(x^2-3))
\infty for infinity
$\lim_{x\rightarrow\infty^{\plus}}\frac{-5x+3}{\sqrt{x^2-5x}+\sqrt{x^2-3}}$
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yes
i got this
now you take a common factor of x from the numerator and a common factor of x^2 in the roots of the denominator
i dont understand
and x^2-5x= x^2 (1-5/x) right?
yesh
and x^2-3 is x^2 (1-3/x^2) right?
its still incorrect apparently?
it is?
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np
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can someone tell me how they got this answer for b please?
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why
why what
why is it 15
