#help-17
1 messages · Page 68 of 1
If you have two lines intersect then the opposite angles at the intersection points are of equal measure, it looks a bit more complicated because we have three angles, but it still applies.
I assume you are German, what Don describes are called "Scheitelwinkel"
verstehe immer leider noch nicht wie ich das ausrechnen muss entschuldige
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if I have $\lambda_1 X_{n\cross m} A_{m\cross m} + \lambda_2 X_{n\cross m} I_{m\cross m} = 2X_{n\cross m} B_{m \cross m}$ with $n<m$, does that imply wlog $\alpha_1 A + \alpha_2 B = I$?
QuAnTuM
wlog?
without loss of generality
im asking whether all the solutions for A and B to the second equation satisfy the first
@fleet quiver Has your question been resolved?
To critically engage with the problem, one should pay particular attention to the matrix equation (\mathbf{X} (\lambda_1 \mathbf{A} - 2 \mathbf{B} + \lambda_2 \mathbf{I}) = \mathbf{0}_{n \times m}) derived from the given equation. Consider the implications of (n < m) for the row-rank of (\mathbf{X}) and consequently for the matrix ( \lambda_1 \mathbf{A} - 2 \mathbf{B} + \lambda_2 \mathbf{I} ). This will allow you to characterize the properties of this matrix in relation to its singularity. Once the matrix's properties are delineated, you will be in a better position to consider whether or not such a matrix condition implies the existence of scalars ( \alpha_1 ) and ( \alpha_2 ) satisfying ( \alpha_1 \mathbf{A} + \alpha_2 \mathbf{B} = \mathbf{I} ).
adzetto
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Find the length (in cm) of an arc of a circle with radius 6 cm if the arc subtends a central angle of
60°.
is it not 6.28?
it is yes
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I have a question about base changement with matrix
i don't get why it's not A' = PAQ^-1
it seems more logical to first change the base with P then applying the function finally come back with the starting base (applying Q^-1)
Yes
Matrix compositions are applied right to left
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I could provide a specific question if wanted but i just had a general quesiton abt composite functions: why do we have to find the domain of the inner(?) function when we're finding the domain of a composite function? wouldnt it makes sence to find all 3: the outer and the inner and the composite and then find the most restrictive for all 3?
why does it make sense to only find the inner one and the total domain
think of functions as machines that take numbers as input and return numbers as output
a composite function is made of two functions in which the output of one is fed directly as input into the other
the "inner" function is the one which sees the input from the outside world
so naturally said input must belong to the input function's domain
and the output of the inner function, which is the only thing that the outer function sees, must belong to the outer function's domain
oh woww
so just confirming; there will never be a time when the output from the inner function's domain will not "fit" in the outer function's domain?
well... no
like if you compose g(x) = sqrt(x) with f(x) = 1 - x^2 with f as the inner
you get sqrt(1 - x^2)
and x=10 works fine with the inner f but you run into issues with the outer g because f(10) doesn't belong to its domain
f(1)?
^^yeah i was confused abt that too
bc its negative ?
and square roots n negatives dont work
so like in this case bc the outer funciton is more restrictive why wouldnt we find the domain of the outer function and the total domain to find the domain of the composite?
truth be told idk what you mean by "total domain"
oh the domain of the compoisite
yea i wored that confusingly
so like the domain of the inner and the domain of the composite and the actual domain of the composite is the overlap of those 2 right
@full vessel Has your question been resolved?
@paper depot ? (sorry to ping)
sadfa;sdlfjka;sd
OK
JUS
A:LWAYS WHEN FINDING DOMAIN OF COMPOSTIE FUNCION
WE FIND DOMAIN OF INNER FIRST THEN DOMAIN OF COMPOSITE THEN OVERLAP AND THATS OUR ANSWER RIGHT
WHO CARES ABT WHY
AS LONG AS THOSE RULES DONT CHANGE I DONT GOTTA KNOW WHY
RIGHT...??
I think @full vessel
It's better for you to understand how mapping for a single function works
Like what does $\map f x$ even mean to you for example
it means that when I enter a value x into a function f it gives me an output
Right
So think of it this way
<tikz>
\begin{tikzpicture}
\node (x) {$x$};
\node[right=of x] (gx) {$g(x)$};
\node[right=of gx] (f_gx) {$f(g(x))$};
\draw[->] (x) -- (gx) node[midway, above] {$g$};
\draw[->] (gx) -- (f_gx) node[midway, above] {$f$};
\end{tikzpicture}
yess i understand
🥹
But anyways
So you see how we are using g(x) for f(g(x)) the same way we had used x for g(x)
yeaap
So
Think of it this way
"You have an x value, and you map (or transform) that x value to g(x) under the transformation (or function) g"
Now the same exact process repeats
"You have a g(x) value, and you map (or transform) that g(x) value to f(g(x)) under the transformation (or function) f
yes yes
i understanaaaanndd but how does that relate to why i have to find the domain of the inner functionnnnnnnn
Because
Let's consider this example
Let's say we have
[
\map g x = -2x \tss{and} \map h x = \s x
]
Can you tell me the domain of both of those
domain of g is all real numbers and domain of h is x > or equal to 0
sqrt(-2x)
Right, that function on its own, what would it's domain be?
x greater than or equal to 0
You sure?
If you plug in x = 1 is that correct
if x is greater than 0 then theres negative in sqrt
x less than or equal to 0
bc the sign flipped bc divide by negative 2 math makes me so sad
Ye
YE
YEEE
What Ann was talking about earlier applied here
h(x) on its own was x greater or equal to 9, but under the composition with g(x), it changed to x Lesser or equal to 0
What you're doing here is making a totally new function
yes
f(g(x)) is different from both f(x) and g(x) obviously. But g(x), as the input of f, needs to satisfy the domain of f too
yeees
when u say needs to
u mean the goal is for the answer to satisfy the domain of f too right
not that g(x) always satisfies f
bc a while back ann gave an example of how even though a number 10 worked for an inner function, it wouldnt work for an outer function ( a square root function(?) bc it turned the value negative
Here for example
yess
g(2) =-4, h(g(2) = undefined
yeah
Just take this as a takeaway:
Functions have inputs, the set of inputs is called the domain. Any input you have for a function must be in its domain, otherwise it is invalid
Composing a function with another requires the inner function to be in the domain of the outer function. Illustrated as g(x) needs to be in the domain of h(x) in the composition of h(g(x))
alright :))
thank you smm@!
genuinely ty for being so patient w me
ygs should be paid for this its crazy how yall arnt
byee
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Bai
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$a$
A Lonely Bean
I think it shows display name by default
no I am talking about
The help channel name
It was always lexqa which is my tag name
Ah that you mean
Now it changed to my display name
i think that was just fixed today
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In the isosceles trapezoid ABCD where the diagonals cross the acute base angles given: AB = c, ADC = a
Given that the perimeter of the trapezoid is 5C find the angle a
AB=c or AD=c?
both
Ya
So, just solve for cos(alpha)
wdym
You have,
C+C+C+C+Ccos(a)+Ccos(a)=5C
yes so c = 2cos(a)
whats the difference?
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any short trick
Use the double-angle formula
@elfin moon Has your question been resolved?
Shortest trick is letting a = b = c = 60 and see which option matches
nah 90, might cause a problem because it makes cos go 0
True
It works fine
.close
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can someone help me with this
i know i need to use one of the equations
i just dont know which one
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
@fallow cloak Has your question been resolved?
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Just look at this
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hi!
can someone help me interpret this question
why is it 720 degrees
when in a circle theres only 360
that's the point
what
one circle have 360 degree, when the question goes beyond that, it's like you continuing doing laps around it
ye
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How do I solve further?!
you've reached till here right $\frac{a\cdot\sqrt{x}}{\sqrt{x} + \sqrt{x - a}}$
nebula40
try dividing the numerator and denominator by sqrt(x). I can't read the last part clearly, but if that's what you've done there you're on the right track
Ok wait I will try more clearly
I got the above one can u give me a hint on 7 no.
try drawing/graphing it
Yeah but we usually don't draw graphs for such questions in our cls
you don't *need * to graph it to get the answer, but it makes it very obvious for this case. and making a small sketch for a small range like (-5, 5) doesn't take any effort at all
@gleaming geyser Has your question been resolved?
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how is the formula simplified? what are the steps?
from step 2 to 3 basically
$\frac{\frac{(x+h)^2}{10}-\frac{x^2}{10}}{h}=\frac{\frac{x^2+2xh+h^2}{10}-\frac{x^2}{10}}{h}=\frac{\frac{\cancel{x^2}+2xh+h^2-\cancel{x^2}}{10}}{h}=\frac{\frac{2x\cancel{h}+\cancel{h}^2}{10}}{\cancel{h}}=\frac{2x+h}{10}=\frac{h}{10}+\frac{x}{5}$ :)
uh oh
MrFancy
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yo i just need someone to check if my answer is right
@high bison Has your question been resolved?
<@&286206848099549185>
Not quite. Try looking at the third line (where you put in 2x into the most inner g(x))
@high bison Has your question been resolved?
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I’m confused about how to draw the graph does it start at 2160 then decrease at 32 students per year for 8 years or is 2160 the currently enrolled number
I think that 2160 is the current number
Ok thanks would you be able to check another question?
sure
i'll see, one moment
what the difference between the step D of 1 and the answer D of 3?
On D of 1 it is subtracting the 6 when it is supposed to be adding it
Since it moved the -6 over
only that changed?
Ya
I’m sure they are the exact same except for the symbol
3 C not d my bad
I said D but meant C
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Hello, I solved till I got the 2 roots and I got the line of symmetry but I am stuck now
x = -43 or x = 34
Line of symmetry = -4.5
How can i find b and c
Show your work?
if it has the same roots it has the same line of symmetry
that should be enough to find b
@tame smelt Has your question been resolved?
.close
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given 4 variables can someone calculate the other 4 ?
if yes please help me
names have no relation to the type of variable
Here's one of them
X = (Left / 100) + (Width / 2)
108 = (Left / 100) + (75 / 2)
108 = (Left / 100) + 37.5
70.5 = Left / 100
7050 = Left
it's algebra yeah
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How do I do these kinds of problems
Or set it up
Do you know how to calculate slope of a line given two points on it?
Yea but I struggle
Umm... where exactly do you struggle?
Like you do the math and get fractions right
Well, not always, but yes.
Yea I don’t know how to graph them
Yea
Yeah. You don't need to graph them to answer this question.
You sure could but you don't need to.
To find out either the line are parallel I thought we’d have to graph it
Umm... wait. You haven't been taught about gradient relationship of the parallel lines?
Maybe we have im not sure I’m not good at math
(gradient = slope)
Ohh
I think their assignment said gradient so i went with that.
Yes.
But we don’t have to graph it to find the slope
So, you just calculate gradient for both of the given lines. If they are same, they are parallel, or else, they aren't.
Yes. I believe you already know how to calculate gradient/slope of a line if you are given two points on it.
So like if both equations come out equal
Where are you getting equations from?
For like number 18 I though I’d have to do
3 - 1
-4 +5
What? No.
Oh
I am not sure anymore if you know the formula. Wait.

Enemagneto
To apply the formula, you should be taking both the points which are on the line.
Like, you have for line 1: (3, -1) and (6, -4)
Enemagneto
Now, calculate for line 2.
If that comes out to be -1 as well, they are parallel, else they aren't.
@dim sail
Where did the -1-(-4) come from
Read from here until the end.
Read the formula
For perpendicular, we have this: Two lines are perpendicular if and only if product of their slopes is -1.
That is if a line has slope $m_{1}$ and another line has slope $m_{2}$, then they are perpendicular iff $m_{1}\cdot m_{2} = -1$.
Enemagneto
One more question about this why did it change to a plus and where did the 4 come from
Wouldn’t 4+(-6) be -2
Yes
Where are you getting those though?
Wait nvm I get it lol
Omg it just clicked in not subtracting down I’m subtracting straight across
Ty for ur help I appreciate it:❤️:
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might want to add the fractions on the top first
add them before plugging it in, make it all one big fraction instead of this mess of complex fraactions
it should give
(6+t)/6t(6+t)
first simplify algebraically
do you know the next step?
How would I add something before plugging it in?
Would it become
1/t + 1t/6t?
don't add it yet, just treat it as an unkown
Treat the variable as unknown?
forget lim t—>-6 for a while and simplify the expression, so that you won't have t+6 in the denominator.
the problem is that t+6 in the denominator causes a problem (by turning into 0) so you have to get rid of this problem
just something else. this fraction can be simplified to 1/6t
ok, let me get my book so I can show you something at least
common denom would be 6t
Which would i multiply by 6t?
Rather why is the numberator still 1?
common denominator would be 6t yes
shouldnt it be 6t/6t
so if we convert each of those fractions to /6t, starting with the one on the left
$\frac1t = \frac{?}{6t}$
hayley!
should be 1t right there
Oh
hold on hold on
Why did you flip here
also how did you combine
the 6t goes below because it was being divided in the numerator. anything being divided in the numeratoe can shift to the denominator
oh ok
Ok i get it
thank you
Never knew everything could just go to the dom like that
i think changing t+6 to 6+t in step 2 to 3 caused the confusion
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how do i make an area model for this?
@glacial meadow Has your question been resolved?
You make a 1x1 square
and divide it into two parts I presume
each are is equal to its probability
so splitting in half is already enough
@glacial meadow
ive never seen an area model so small
I thought you always make a 1x1 square
such that the entire area is 1
isn't the purpose of it to let area and probability be equal
in this case each option has a probability of 0.5
so just split it into left & right
0.5x1 and 0.5x1
one half blue, the other red
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need help factoring a polynomial. the question is "Factor the following polynomial using the negative of the greatest common factor.
-27x^2 + 63"
What’s the gcf here
3
oh its 9
-9
i got 3x^2-7
Ye
ok thanks!
Np
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What does it mean to rationalize the denominator?
manipulate the fraction such that the denominator is a rational number
for instance, the denominator of the first fraction is sqrt(2), which is not rational
How can I change that?
multiplying the numerator and denominator by the same thing doesn't change the value of the fraction
find something to multiply sqrt(2) by such that you get a rational number
So the answer of 49 is rad2 over 2
yes
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Prove that n^2<3^n for every n is part of {0,1,2,3,...} using mathematical induction
f
Mmm?
what have you done so far
Did the base case, induction hypothesis and started the induction step with
We wish to show that (k+1)^2<3^(k+1)
what inequality do you already have ?
k^2<3^k
is it simpler to transform k^2 into (k+1)^2, or to transform 3^k into 3^(k+1)?
3^(k+1)
how do you transform 3^k into 3^(k+1) ?
Multiply by 3 so 3*3^k=3^(k+1)
now modify the inequality k^2 < 3^k so there's a 3^(k+1) !
3k^2<3^(k+1)
to prove the desired inequality (k+1)^2 < 3^(k+1), is it enough to prove that (k+1)^2 < 3k^2 for some k ?
Yes
(in mathematical induction, you can start the induction at any k that you want so long as the cases beforewards are verified)
what do you get when you solve for k in (k+1)^2 < 3k^2 ?
2k^2-2k-1>0
it's a quadratic inequality, so you can solve it
also you got the direction flipped around
Well from looking at it, k>or=3
Oh I see
so you only need to check the base cases 0, 1, 2 (because you need the inequality to hold if you want to use the induction principle)
after you verify that the base case n = 2 holds, the inductive argument will fill in the rest of the cases
Wait I just want to make sure I get what's happening. So we get to 2k^2-2k-1>0 and we realize that it works for k>=2. Because it doesn't work for k=0 and k=1, we just have to plug in those cases normally to the original equation. We don't have to plug in the other cases because those are covered by the inductive arguement since 2k^2-2k-1>0 works for k>=2.
Am I understanding that correctly?
you have to check the base cases k = 0 and 1 because they cannot be a part of the inductive argument
but you also have to check the base case k = 2 because that one will be the actual basis of your induction
But don't we already check it with k>=2?
k >= 2 only checks that [if the claim holds for n = k, then it necessarily holds for n = k+1]
you have to kickstart the engine with k = 2
basically you need to check if really n^2 < 3^n for n = 2
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Hello
bc there are 2 xs on each side
it does it for this to tho
So for every area problem its just gonna be 2x added
alright thanks
np
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hii im writing my notes and i have a question, how do i write (-2+-59) properly? since there's a plus sign and a negative in the middle thank you
do you want to do -2-59
im asking how to write (-2+-59) properly hehe, it looks wrong thats why bc of the two signs in the middle
or is it just how it is? 😭
there should only be one sign
how do i write it?
you probably want to write (-2-59)
ohh but what about the add sign ? 😭
👍
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Halp
Help me to know: if I did em correctly, and if my steps to find if its R or IR were wrong or right, and help me solve the ones where I put a “?” And yea
Ping me
dot means recurring?@vast shale
Yess
@vast shale your answers for the first one look good to me. For the ? one you have 0.111111.... hint is there a fraction that equals this (further hint, what if you consider the multiples of it, 0.2222..., 0.3333...., and so on, do you get to 1? How many times do you need to add it to itself?)
For the second one, also looks good to me, for sqrt(2) + sqrt(3), it's a little tricky to actually prove, but it is irrational.
Consider a^2. If a is rational, then a^2 is also rational. So consider (√2 + √3)^2 = 5 + 2√6. We know that this number is irrational because it's the sum of a rational and an irrational. Therefore, √2 + √3 cannot be rational
(proof by contrapositive)
(If p then q implies if not q then not p.)
@vast shale Has your question been resolved?
@spiral turtle so the i part or Q1 is “0.11” ? Or is it 0.111..? If its 0.111.. den its rational and, sqrt 2 + sqrt 3 is irrational as they cant be added + rational nos are simple so ye, and are my steps right for Q2, part c and f?
consider log base 10. log(2) is irrational. log(5) is irrational. log(2) + log(5) = 1. It's not always true that adding two irrational numbers always results in another irrational number.
My bad, c is rational.
That was incorrect, for Q2
f is correct though.
@vast shale
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I'm not sure how to solve when ln or e is part of the function, and got stuck on these two questions
They look similar, so is there some trick to solving these both?
Did u find f(3) and f(1)?
It’s just plugging in and some log rules
No trick or Anything
No, I don't know what to do with the ln once I get to ln(3^2+1) or ln(1^2+1)
Yea I'm mainly stuck on the actual log stuff
f(3)=ln(10)
Great, now do the same for f(1)
f(1)=ln(2)
Good, now what do we have altogether?
ln(10)-ln(2)/3-(-1)
ln(10)-ln(2)/4
$\frac {\ln (10) - \ln (2)}{4}$
Stephen
Use these rules to simplify the numerator
One of these rules applies to the numerator
Ln(10/3)=ln(5)?
Stephen
Use another log rule so that the 1/4 enters the argument of the ln function
Log(5^1/4)?
Stephen
7 shouldn’t be all that hard, it’s just plugging in
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Let $p(x)$ be a polynomial of degree 2010. Suppose $p(n)= \frac{n}{1+n} \forall n∈ {0,1,2...,2010}$. Find p(2012)
My solution: Let $p(x)= k(x)(x-1)(x-2)...(x-2009) + \frac{x}{1+x}$
Is it correct? If not, why?
Feynmann
Use Lagrange polynomial
Idk what that is
Search it, under the term “Lagrange polynomial” on Wikipedia
Can you explain why my method is wrong?
Here is what it
Goes like:
$P(x)=\sum_{0 \leq i \leq 2010}\frac{i}{i+1}\frac{\prod_{0 \leq i \leq 2010, j \neq i}(x-j)}{\prod_{0 \leq i \leq 2010, j \neq i}(i-j)}$, therefore what you are looking for is $\sum_{0 \leq i \leq 2010}\frac{i}{i+1}\frac{\prod_{0 \leq i \leq 2010, j \neq i}(2012-j)}{\prod_{0 \leq i \leq 2010, j \neq i}(i-j)}$
Cogwheels of the mind
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hello everyone
to bases of which vector space do i need to extend the LI sets
to bases of $\mathbb{R}^4$?
calculus is fun
No
They didn’t ask you to do anything like that
Oh sorry didn’t see the last line
np
i didnt see it too at first when i solved the question and wanted to jump to another one i noticed this
XD
Yes you need to do this for c
how do ik that it is a basis of $\mathbb{R}^4$
calculus is fun
If you checked it’s linear independent then it is a basis already
Okay
to extend the set in c i just need to add vector in which the set remains LI
Yeah
It’s sufficient to find one orthogonal to all that three
A system of linear equations, 3 equations 4 variables
so triple cross product
I don’t think there is such a thing
why is there not such a thing
cross product of 2 vectors is a vector
so we can have a cross product with the resulting vector and another vector
or wait a sec
i made something wrong
these elements are just called vectors but they arent vectors in fact
they are different from vectors that we deal with
so we cant do a cross product like that
but we can consider 2 vectors made by these 3 elements and then perform cross product
after that we solve for the coordinates of the new point to get the 4th element of the basis of R^4
Actually if you want , you can define such a concept, just not very necessary:
n-1 vectors in F^n
You write them as column vectors, n-1 columns
Add one more column, whose elements are e_1,…,e_n
Its determinant
You can name it yourself, it is a vector orthogonal to all these n-1 vectors
Work just fine as the three dimensional case. I don’t know or have a name for it.
i was trying to do something like that which is to reach a cross product which will be computing a determinant
(Just a basic result by the property of determinant
but the problem i got is that i should have 3 vectors not 2
otherwise i wont obtain a square matrix
but can i consider these elements to be vectors
i mean they are called vectors but arent the same as vectors $\vec{v}$
calculus is fun
they are called vectors just because they are elements of vector spaces
but in fact they are just points
but then we can just consider them vectors staring from origin and ending at that point
i could just do that
i am stupid
Good. People who think themselves being smart are actually stupid
yea smart people dont say hey i am smart because this sentence itself is stupid
Yeah
so people who say hey i am smart are stupid XD
You can do this
yes
is what i said here correct
Yeah, I think that’s how people normally view point as a vector or conversely
this will lead to the same determinant that you said but the elements are flipped 90 deg counter clockwise
which will give same result
the det ill obtain will have each row containing all 4 components of the same vector
the first row will be unit vector
tysm for you help
Np
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hello everyone
no it is not this is the first time this appears
so there should be a way to know what this means
what's your book called again
this might be it
yes that is in fact definitely it.
linear algebra by werner greub
ok so ill try this and type what i get
yea they must be natural because they are used as indecies of lambda_i
arent these equal just because $C{1,.,n}={\lambda _1,...,\lambda _n}$ where $\lambda _i \in \Gamma$ for $i=1,2,..n$ and $\Gamma ^n$ is the set ${\lambda _1,...,\lambda _n}$?
\{ ... \} for braces
yea i forgot that
also no "Gamma^n is the n-tuple (lambda_1, ..., lambda_n)" is very stinky
C(set) consists of functions
you confuse a set of things for a generic thing from it
not tuples
this is like confusing the concepts of "Spain" and "a Spaniard"
wait i meant the set not the tuple because each lamba_i is just f(i)
no
ok
calculus is fun
why
btw description of stuff inside {} should also be written inside those {}
wdym
people who confuse a set for its generic element don't like that.
ahhh this thing again i just wasnt focusing on writing thats all
yes you are right but this happened already so i will do that from now on i cant travel back in time
so what's the wrong part
the things we said
so only notations
"only"
so is this correct now after i corrected notation mistakes
that's like me writing lahfncpuw and the only wrong thing being spelling
you have to rewrite it from scratch and properly.
ok i will eventhough i can just copy paste it
arent $C{1,..,n}$ and $\Gamma ^n$ equal because $C{1,..,n}={\lambda _1,..,\lambda _n}$ , $(\lambda_1,..,\lambda_n) \in \Gamma ^n$ and $\Gamma ^n$ is a vector space over $\Gamma$ with dimension $n$
....
no its not because f maps ${1,..,n} \to \Gamma$
calculus is fun
and you wrote Gamma^n instead of Gamma
calculus is fun
is this better now
i thought the problem was writing that $C{1,..,n}=(\lambda_1,..,\lambda_n)$ instead of ${\lambda _1,..,\lambda _n}$
calculus is fun
both of thse are wrong
isnt $C{1,..,n}$ a set so its elements are in braces
yes
calculus is fun
but what you wrote isnt its elements
ok it is the set of functions f(i) for i=1,2,..,n
and f(i)=$\lambda _i$ for i=1,2,..,n
calculus is fun
so how arent $\lambda _i$ the elements of this vector space
calculus is fun
bro this ' is annoying
its elements are the functions evaluated at different values
wait wait i just said stupid stuff
let me rethink for a bit
how are we considering all maps f and specifying a single map f at the same time
are we talking about all maps f that satisfy $f(i)=\alpha_i$ for i=1,2,..,n and for all tuples $(\alpha _1,..,\alpha_n)$ where one tuple is $(\lambda_1,..,\lambda _n)$
calculus is fun
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need help on simple quadratic equation I'm stuck on 4x²+4x=24 (if I'm even on the right track)
You made the problem even harder by expanding (2x + 1)^2
Yeah don’t expand
ohhhh
Instead move the 25 to the other side and take sqrt of both sides
hol up

Difference of 2 squares.
25 is a square. (it actually didnt need to be - you can still use difference of 2 squares, but have square roots)
Ah or that yeah
yeah so 25 becomes 5 right, but what abt the other side, (2x+1)^2 how does that work when we sqrt
no, do not square root both sides of an equation unless that is a last resort
it is better to factor
,,a^2 - b^2 = ???
okay so I sqrt 25 and not the other side?
do you recognise this?
no..
,,a^2 - b^2 = (a+b)(a-b)
This?
multiply out the right hand side to check its true
This is called "the difference of 2 squares"
ahhh
You can directly use it here
so, I have to apply this in the very first original equation of (2x+1)^2-25=0?
yes.
ill brb to figure this out
So as an extra comment - you can do what was suggested at first. "square root both sides", but you must remember the plus or minus
x^2 = 1, means x is +1 or -1.
So thats why I didnt recommend it.
I still dont get it like how to apply the equation itself, could you do it then I'll prob be able to learn from that example
specifically since there is a ^2 outside 2x + 1 and in the graphic shown its only a and b squared
,,(2x+1)^2 - 25 = 0
So I claim that the left hand side of your equation is in this form
so you need to tell me what a and b are if that is true.
2x and 1 ????
no.
(If you haven't done so far, note that 25 is a perfect square)
,,(2x+1)^2 - 25 = a^2 - b^2
That's what I'm claiming
for the right choice of a and b
if a = 2x, b = 1 like you suggest
You just get (2x)^2 - 1^2 which is not what you got
yeah im lost, can you just do the steps on how to use the thing you suggested and apply my equation on it. I'll learn that way than guessing it for myself cause I genuinely don't got a clue what all this means
Right ok
thank you sm tho
let me change the numbers then u can do the same thing on your originnal
,,(3x-1)^2 - 36 = 0
sure thatd be even better actually
\begin{gather*}
(3x-1)^2 - 6^2 = 0
\end{gather*}
so i can do mine on my own
let a = 3x - 1, b = 6
then we directly use this expansion
so we have this, and this can be simplified with a bit of algebra
Do you now know how to solve this?
hol up not yet but this is for sure better now I can learn from dis
I get the procedure now just a bit confuse on some areas but def doable, Thank you sm for your time, I'll study this thoroughly tomorrow I gotta sleep now. Thanks again
Alright no worries. I did make it more complicated than needs to be in some ways
but the usual way that is taught can often easily result in errors
And so I prefer this way
hmm okay okay thanks
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knowing that cos(2a) = 2cos²(a) - 1, find the value of cos²(pi/5) and sin²(pi/5)
shouldn't it be $2cos^2(a) -1 =cos(2a)$
yeah
no gaps
oops , thanks]
physicsrocks

which angles trig ratios are you allowed to use?
If you can use the trig ratios for 18deg for instance, it isn;t too hard
no mention of that
only thing given earlier is omega = e^(2ipi/5)
alpha = 2cos(2pi/5)
beta = 2cos(4pi/5)
i could give you the whole thing but its in french
if it can be of any help, i also have the value of cos(2pi/5)
i did that, but must have messed somewhere because i end with cos²(pi/5)-(1-cos²(pi/5) = 2cos(pi/5)-1, and cant find where is the problem
because cos(2pi/5) = cos²(pi/5) - sin²(pi/5)
fuck i'm just dumb, i forgot i had the numerical value
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✅
that aint interval notation
your set builder is rather questionable even if it wanted that btw
{x : -infty < x < infty} makes better sense.
But this is not interval notation
yeah if they wanted set notation they'd also have to provide symbols for subsets etc
I agree with you. It says in interval notation and it is linear function.
so stupid
that it has to be a specific format
but doesn't tell you what that looks like
lemme see
nothing works so far
OH
I SEE
okay okay
I got it
thank you guys
typo ==> |
one more question
weird size but how do you make a function that starts with division?
Let me see what you did, plz
nothing yet
this is the earlier problem though
the one I asked for help with was an example problem
It is exactly the same process. divide 8; add 5; and multiply the whole thing by 2. I am assuming that you may need to simplify before it accepts the answer.
hmmm


