#help-19
1 messages · Page 83 of 1
Oh , thank you!
there is a minus in the third equality though
so?
ren
both minuses dissapeared XD
$E(x) = \arcsin ( \sin (2x)) ; \forall x \in \R =>\newline \sin (E(x))= \sin (2x) ; \forall x \in \R <=>\newline -\sin (E(x))= -\sin (2x) ; \forall x \in \R <=>\newline\sin (E(x)- \pi)= \sin (2x- \pi ) ; \forall x \in \R <=>\newline E(x) - \pi = \arcsin(\sin(2x- \pi)) + 2k \pi ; \forall x \in \R ,; k \in \Z ; <=>\newline E(x) = \arcsin(\sin(2x- \pi)) + \pi (2k + 1) ; \forall x \in \R ,; k \in \Z; <=>\newline\arcsin(\sin(2x))=\arcsin(\sin(2x- \pi)) + \pi(2k+1) ; \forall x \in \R , ; k \in \Z \newline (FALSE)$
its fine
Peel3
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np
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"Let g(u, v, w) be differentiable on R^3
and let f(x, y, z) = .... Use the chain rule to
show that for all (x, y, z): xyz ̸= 0 holds:..."
could someone help me solve this?
@elfin warren Has your question been resolved?
<@&286206848099549185>
@elfin warren Has your question been resolved?
Is r a vector or what exactly
I am not entirely sure
ok can you try to get f_x, f_y and f_z?
Yes, for example:
$\f_x = g_x \cdot \left ( \frac{1}{y} -\frac{z}{x^2} \right )$
𝔸dωn𝓲²s
F_x = g_x * y + g_z * z?
$\frac{\partial f\left (x,y,z) \right )}{\partial x} = \frac{\partial g \left ( \frac{x}{y},\frac{y}{z},\frac{z}{x} \right )}{\partial x} \cdot \ \frac{\partial}{\partial x} \frac{x}{y} + \frac{\partial g \left ( \frac{x}{y},\frac{y}{z},\frac{z}{x} \right )}{\partial x} \cdot \ \frac{\partial}{\partial x} \frac{y}{z} + \frac{\partial g \left (\frac{x}{y},\frac{y}{z},\frac{z}{x} \right )}{\partial x} \cdot \ \frac{\partial}{\partial x} \frac{z}{x}$
𝔸dωn𝓲²s
HAHA
That looks complicated
I have to think if it's like that
If f(g(x) we get f'(g) • g'
If f(s,t) we get f'(s,t) • (s' + t') or
Hmm okay
So this is it if you do it very detailed
Ohh okay!
I think I will have to continue tomorrow unfortunately but maybe I will see you then!
Thank you for the help so far!
np
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id appreciate any help this ones been hurting my head for a min
are u familiar with lagrange mutlipliers?
@azure spruce
u may not need it, but i always find it to be the easiest method for these types of problems
yeah i am
alr, why dont u try applying that here?
im up to 8y-6(8x-4)-6=2Lambda
alr hold on lemme check that rq
i dont think im getting that exactly
can u show ur work
been struggling with this topic for a while 😭
ill try see where i went wrong
$<8y-6x - 3, 8x-4> = L<2,3> \newline 2x+3y = 4$
Stephen
Stephen
although i am a bit confused with the 2x+3y =4
wait no
im not thats the constraint
yea
so now id take the first two equations
solve for L
then set them equal
upon doing that we get
$\frac {8y - 6x - 3}{2} = \frac {8x-4}{3} \newline \newline 2x+3y = 4$
now we have a system of equations that we can solve
i see
would you mind helping me understand how to get from the first two equations to when we set them up to be equal
im not exactly sure how
$8y-6x - 3 = 2L$
Stephen
/2?
yea /3 for both sides in the second equation
and once they are both equal to L, we can set them equal to one another
and theyd both be equal to L ?
Stephen
trying to rn
no, why?
sorry im confused
we have 2 equations in terms of x and y
why solve for lambda
we dont need it
yeah your right
just solve for x and y
i got x = 24y- 19 / 16
just sub to other eqn
into the constraint ?
is y - 17/16 ?
thats what i got im not too sure tho
sorry i meant y= 17/16
@royal herald is it correct ?
<@&286206848099549185>
question?
.
this one
got up to here
id really appreciate if you can help me understand
oh i see
cross multiplication
<@&286206848099549185> ngl im really stuck any help if possible ?
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Hi
Do you got the original question?
Which part?
What?
@thorn imp Has your question been resolved?
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Hello! I dont understand how the original 2 fractions in the numerator were turned into the 1 fraction in the first step. Can someone please explain? Thanks
How? I know this is basic and I normally do this flawlessly but for some reason in this scenario it doesnt make sense to me
so the left fraction gets multiplied by 2/2
making the numerator 2
the right fraction is multiplied by x+2/x+2
making the numerator x+2
however since there's a minus
the numerator is 2 - (x+2)
making it 2 - x - 2
d'y know how to add fractions
But why 2/2
thanks! I really do not why this stumped me
prob the second way to do it is easier
ive had a lot of work to do this week so my brain is tired maybe
@twilit pecan Has your question been resolved?
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I've been getting into card games lately and I want to use this as an opportunity to learn more about probability.
The scenario I'm on is the following (assume a shuffled standard 52 card deck):
- After drawing 5 cards, what is the probaility of drawing an ace?
- Remove 5 cards from the deck
- Draw an additional 5 cards. From the 10 cards drawn so far, what is the probability of drawing an ace?
I understand how to do part 1. The idea is to find the probability of drawing NOT drawing an ace and subtracting that from 1.
So you get the following:
P(at least 1 ace) = 1 - 48C5/52C5
I struggle with understanding how the question changes after I remove 5 from the deck, then draw 5 more cards.
Any help is appreciated.
@faint tusk Has your question been resolved?
i assume that you haven't found an ace after number 2?
also, which 5 cards are removed from the deck?
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No. The question is asking for the probability of finding at least 1 ace. Whether you found an ace or not, it makes do difference for the probability.
So you draw 5 cards without putting them back and you want to calculate the probability of getting at least one ace?
yes
yup your first calculation seems correct
Part 3 would be very easy if you knew the probability distribution for the amount of aces in the deck prior to drawing the last 5 cards
but figuring out the distribution is a little challenging
distribution of aces left
4 aces => none got chosen in step 1 and none got chosen in step 2
3 aces => one got chosen in step 1 and none got chosen in step 2
OR none got chosen in step 1 and one got chosen in step 2
2 aces => one got chosen in step 1 and one got chosen in step 2
OR none got chosen in step 1 and two got chosen in step 2
OR two got chosen in step 1 and none got chosen in step 2
1 aces => 0 and 3, or 1 and 2, or 2 and 1, or 3 and 0
0 aces => 0 and 4, or 1 and 3, or 2 and 2, or 3 and 1, or 4 and 0
It's a bit of work but it's doable
^^^^ yeah
@faint tusk Has your question been resolved?
thank you 🙏
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what do I do, right now I think having the chart only gives me one estimate
this is riemann sums right?
ye
so we have two options here, LRAM and RRAM
since it says that the runner’s speed is steadily increasing
which one is going to be the overestimate and which is the underestimate?
I think right is upper and left is lower
yep exactly
so we just need to perform both RRAM and LRAM using the table of values it gives us
and that’ll be it
ok ty
i havent done rieman problem yet so ill watch a vid then try and see if i get it right
alright
@analog tundra Has your question been resolved?
@cold swift for the lower estimate I did (0.5 x 0) + (0.5 x 5.7) + (0.5 x 11.2) + (0.5 x 14.1) + (0.5 x 18.8) + (0.5 * 19.8) = 93.04 what was I supposed to do?
@analog tundra Has your question been resolved?
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Can someone tell me if this is right
Asap
i just do the first one then on the second equation i turn it into standard form?
Or a other form idk the name
@round shore Has your question been resolved?
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Can someone please help me solve question g
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This might be a rather general question but this is largely due to my lack of understanding in linear algebra.
I'm self studying from the gilbert strang textbook and don't really have access to a teacher because Australian highschool doesnt teach linear algebra at that level.
However, for the cross-product, it seems like finding the determinant of a 3x3 matrix with i j k going across as its columns or rows (whatever is considered conventional) does the trick.
My question is: is this purely notational/nmnemonical or is there an actual explanation for putting unit vectors into the matrix
Im interested in learning it because vectors are part of the highschool assessment course and it seems matrices simplifies a lot of these questions significantly but it is required for me to be able to formally define and explain the processes if i intend on using it in my exams
i have some limited understanding of duality from the textbook and some other readings but i dont think i understand it fully either
cross product being evaluated by the determinant is just a coincidence as far as i know
determinant is a much more general concept in R^n
cross product is only defined in particular dimensions
there seems to be more to it but i dont understand it either since i havent formally done lin alg
i would've thought that if you do a 3x3 matrix with ijk and ur 2 vectors, it geometrically generates a parallelpipen
yes that is true
parallelepiped
the area would be a parallelogram
|a x b|
hmm ok
im just not sure how to correlate that with the fact that the determinant computes the vector perpendicular to both tho
because afaik the determinant generates an area
oh the thing is
we dont actually compute the determinant when we use that method
we just perform cofactor expansion and leave it in that form
its purely for technical purposes
oh so like i(minor) + j(minor) + k(minor) ?
yes
we wouldnt compute whats inside the ijk but in normal determinants we would and ijk would be numbers rather than basis vectors
ok that seems fair enough, from the stackexchange post you linked there seems to be some actual geometric significance but i dont think i will understand at this stage, for now i will probably just treat it as a notational trick for computing it and write it in the expanded form
thx for ur time!
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can sm1 help me
yea post your question
with these
whats your understanding of probability?
probability basically refers to the "chance" of something happening
how do i work it out?
yea
the chance of the sweets beingred
yea, and how many sweets are red
nah
4 are red]
the question is
what is the chance of you getting a red sweet
if you pick a random sweet
the chance of me getting a red sweet it 4 / 15 ?
from this specific jar ofc
yea thats right
mhm
very good
now the next one
if you have green and blue counters
and you pick a counter RANDOMLY
the chance of the counter being green is 0.3
now what u gotta realize is the fact that you can only get green or blue counters
so the chances of both added together (chance of green) + (chance of blue) = 1, because you cannot have any other outcomes!
but how do i know the other color
ohh
0.7?
for question 14 how do i do it
6x 4 - 5?
24-5
19
ohh
ty
i gtg
too
bye ill come back tmrq
y'all should i .close this
...
should i tho
it's only been 20 mins
...
i feel bad
what if they come back
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fine
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Hello. That is an Olympiad task for 11th graders from 2001. For real numbers x,y,z which are greater than 1 each, prove this inequality
translate
I tried squaring both sides which didn't give me anything
I already trasnlated
Also 1/x + 1/y + 1/z =2
Also I think it comes to everyone's mind that x+y+z > 3
if you're looking for a solution, the olympiads provide solutions
really? But where I find it😭
is this russian
yeah
I FOUND IT
For some reason it is located in the middle of the book
No paper economy)
Gonna send you all a solution here
Also. How these types of statements are called and where to find those? For example here an already proven inequality is used
I want to see those, is it number theory or iam wrong?
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Question 11 please help
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i need help with this, i have a test next week abt it and i might be screwed 😭
look up
inside angles theorem circle
i just now did and it’s still confusing me, i can’t watch videos right now
what's confsing about what you read
okay that makes more sense
is that all?
yes
it was obtuse so it couldn’t be that so i subtracted it from 180 (102)
and it was correct
im confused on this too
outside angles theorem circle
okay its 2 secants
but im having trouble solving them
what are you seeing when you searched it up
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How do I show associativity for this?
I feel like there's a better way than just showing all combinations of reflections and translations
associativity of composition is well known
rrr
ttt
trr
rtr
rrt
rtt
trt
ttr
Would be all the combinations but it seems like quite a bit
Do you think it would be sufficient to prove that function composition is associative and just state that all combinations of reflections and translations would be composition of functions?
well reflections and translations are functions
if the composition of all types of functions is associative, then certainly the composition of only a few types of functions is associative aswell
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how would i know the line of Centre isnt horizontal or perpendicular?
one of them is moving diagonally, and they have to collide somehow, so if they were directly vertical/horizontal to each other you wouldn't expect them to hit each other (given their velocities)
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This is the question, I attached the wrong one 😭
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how do i do iv)
im so confused
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@silver fossil Has your question been resolved?
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[
\begin{align*}
f(x) &= -2x^2 + 7x - 4 \
f(a + 2) &= -2(a + 2)^2 + 7(a + 2) - 4 \
&= -2(a^2 + 4a + 4) + 7a + 14 - 4 \
&= -2a^2 - 8a - 8 + 7a + 10 \
&= -2a^2 - a + 2
\end{align*}
]
did i do it right?
mcor42
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Hi, I was hoping someone could check my proof for this problem 
@desert marlin Has your question been resolved?
Looks fine to me. The only comment I have is that you seem to have split this up into three cases even though that was unnecessary because there are really only two (|a| is finite and |a| is infinite). The third case you showed is really just the contrapositive of the first statement.
actually it's not strictly the contrapositive but it is implied by it
Ah okay. Thank you
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what is this??
@mystic saffron Has your question been resolved?
<@&286206848099549185> sorry, any of you guys know gaussian quadrature?
😭 im so screwed
An explanation of Gaussian quadrature. An example of how to calculate the weights and nodes for two-point Legendre-Gauss quadrature.
Join me on Coursera: https://imp.i384100.net/mathematics-for-engineers
Lecture notes at http://www.math.ust.hk/~machas/numerical-methods-for-engineers.pdf
Paperback at https://www.amazon.com/Numerical-Methods-E...
This might help
@mystic saffron Has your question been resolved?
oh my god
i stared at this question
for 3 hours
and it finally clicked
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Hello
Merp
whats your question?
!xy
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
How do to add a log that have diefferent in basid
Basis
Addition of logarithms with different bases, how?
you can use change of base, but that would be ugly
@frozen atlas Has your question been resolved?
<@&286206848099549185>
What exactly is written in the last line
1/2 * (a*log(b) + b*log(a)) ?
what are the basis and what are the log values?
when you write "alogb" what do you mean
log_b(a)?
log_a(b)?
a * log10(b)?
I found these
what the hell is that notation
"Its known that" bla bla "where" bla bla "and" bla bla, "so the value of" bla bla
ok I presume log_b(a²) and log_a(b²)
other way around
log_a²(b) & log_b²(a)?
$^{a^2}\log(b) = \log_{a^2}(b)$
ℝαμΩℕωⅤ
who invented that
nywys the only property you need is:
log_a(X) = log_b(X) / log_b(a)
which you can use to change to any basis
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If X1, X2,..., 1991 are strictly positive numbers and x1 + x2 + .... + X 1991 = 1, show that 2(√x1(x2 + x3 + ... + X1991) + √ x2(x1+x3 + ... + x1991) + ... + √x1991 (x1 + x2 + ... + X1990)) <1991
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@blissful depot Has your question been resolved?
I got up untill 2(√x1(1-x1) + √x2(1-x2)...+√x1991(1-x1991))<1991
🥲
<@&286206848099549185>
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<@&286206848099549185>
the 2 up here is really messing with me
otherwise it seems easy enough
Right
Dividing it all by 2 makes it worse
<@&286206848099549185>
@blissful depot Has your question been resolved?
Hint: $2\sqrt{a(S-a)}\le S$
Caroline
are you sure this is true? i dont think equality ever holds
but anyways just use jensens
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in this question, i have to solve for n, and i got n=6, which is a valid solution
however, by guess and checking, you also find that n=3. i seem to have missed this solution, probably when i cancelled (n-3) from both sides in the middle
how would i mathematically get n=3, and how do i avoid missing solutions in the future for other questions?
2nd and 3rd line is pascals identity btw
move it over and factor it
wdym by move it over?
oh subtracting 20(n-3)
i tried to divide 😭
well if n=3 then you're essentially dividing by 0
after a bit of factoring and everything, i end up at $(n-3)(n-1)(n-2)=0$, but n=1 and n=2 aren't valid because n>=0 for combinations
ـDraedon
*because n>=r
so >= 3
so how do i get n=6 from this?
$(n-1)(n-2)(n-3)-20(n-3)=0\newline$
$(n-3)(n-1)(n-2)(-20)=0\newline$
$(n-1)(n-2)(n-3)=0$
ـDraedon
oh i see
so you automatically get n = 3 as an answer
and the rest is (n-2)(n-1) - 20 = 0
which is what you did
that you got your n = 6
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That's called linearity of the dot product yes
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Given that:
A = { x : 5 < x < 12, x ∈ R }
B = { x : – 3 < x < 8, x ∈ R }
C = { 2x : –1 < x < 5, x ∈ Z }
(a) Express in similar set-builder notation the following sets:
(iv) A’ n B’
(b) Find
(ii) n ( B U C )
for part (a), i got x smaller or equal to 3 or x is bigger than 12
how do i show it in a similar notation?
set builder notation is just {some_expression: condition_to_be_satisfied}
i have 2 two different conditions?
or should i express it as it can't be bigger than -3 and smaller than 12
You can use logical operators i.e. (or, and): e.g., condition 1 or condition 2.
ohh ok
thx
@honest quest btw for part b, is it possible to find the number of elements in a set B?
since it's real numbers
You can put down infinity as the answer
x is a set of real numbers 💀
oh
is the ans 7?
there should be something like "x is a member of the set of real numbers"
or "x is a real number"
but not x is a set of real numbers
oh it was like x E R
yes, that means x is a member of R
∈
yeye that symbol
Also suspicious
no
number or elements
are you sure its B union C
then there are infinitely many numbers
oh
I don't think it be larger necessarily because you would need to consider bijectivity but it does not matter
(larger or equal is what i meant)
not strictly larger ofc
that's also because the elements in C might already be contained inside B
although checking the sets, its not the case
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"Let g(u, v, w) be differentiable on R^3 and let f(x, y, z) = g(x/y, y/z, z/x). Use the chain rule to show that for all (x, y, z): xyz ̸= 0 holds:"
can anybody help me solve this?
Chain rule!
𝔸dωn𝓲²s
So you need $\begin{pmatrix} x \ y \ z \end{pmatrix} \cdot \begin{pmatrix} f_x \ f_y \ f_z \end{pmatrix} =
\begin{pmatrix} x \ y \ z \end{pmatrix} \cdot \begin{pmatrix} g_u \cdot u_x + g_v \cdot v_x + g_w \cdot w_x \ g_u \cdot u_y + g_v \cdot v_y + g_w \cdot w_y \ g_u \cdot u_z + g_v \cdot v_z + g_w \cdot w_z \end{pmatrix}$
𝔸dωn𝓲²s
is that the same thing as this?
yeah okay
so let's do f_x
𝔸dωn𝓲²s
What is u_x v_x and w_x
is u_x not just y?
not qute
u = x/y
now diff. wtr to x
the constant is 1/y not y
so u_x = 1/y
can you follow?
okay i think so
1/3
okay
v_x?
0?
hmm -2/x^2?
-z/x^2?
,,f_x = g_u \cdot \frac{1}{y} + g_w \cdot \left ( -\frac{z}{x^2} \right )
𝔸dωn𝓲²s
𝔸dωn𝓲²s
same game
𝔸dωn𝓲²s
,, f_z = g_u \cdot u_z + g_v \cdot v_z + g_w \cdot w_z
𝔸dωn𝓲²s
same game
uz = 0, vz = -y/z^2 , wz = 1/x?
𝔸dωn𝓲²s
$\begin{pmatrix} x \ y \ z \end{pmatrix} \cdot \begin{pmatrix} f_x \ f_y \ f_z \end{pmatrix} =
\begin{pmatrix} x \ y \ z \end{pmatrix} \cdot \begin{pmatrix} g_u \cdot \frac{1}{y} + g_w \cdot \left ( -\frac{z}{x^2} \right ) \ g_u \cdot \left (-\frac{x}{y^2} \right ) + g_v \cdot \frac{1}{z} \ g_v \cdot \left (- \frac{y}{z^2} \right ) + g_w \cdot \frac{1}{x} \end{pmatrix}$
𝔸dωn𝓲²s
Now we need to do the dot product and simplify the terms
at best factor g_u, g_v and g_w
is the simplification not just going to look like this?
Yes
Yes
So we have proven it now?
If you did the dot product and simplified it to what you just sent, yes
See math is so easy
jk
thank you too
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Since Reddit hasn't gotten the exact explanation on how, I'll just post these here until someone can (unless no one sees this)
This is quite hard tho so idk be prepped for this one
you're taking 5 marbles, 4 of which are colored, and the remaning if colorless
you can have 4r,0b,1c; 3r,1b,1c
check these probabilities again
@alpine swift Has your question been resolved?
0.0162+0.0004+0.0027 < 0.03645
P(4r, 0b, 1c)+ P(3r, 1b, 1c)+ P(3r+ 0b+ 2c)< 0.03645
i have a bit in mind
if the majority in the sample are red, then wouldn't the fact that only 1 or 0 blues exist?
P(0r, 0b, 5c)+ P(1r, 0b, 4c)+ P(2r, 0b, 3c)+ P(3r, 0b, 2c)+ P(4r, 0b, 1c)+ P(0r, 1b, 4c)+ P(1r, 1b, 3c)+ P(2r, 1b, 2c)+ P(3r, 1b, 1c)
0.00781+ 0.02256= 0.03037
this is close woh
hmmm
wouldnt it be also called majority if 2 red and blue balls happen
P(0r, 2b, 3c)+ P(1r, 2b, 2c)+P(2r, 2b, 2c)
0.03816
<@&286206848099549185> still stuck btw
@alpine swift Has your question been resolved?
<@&286206848099549185>
Flux Fissionist
@alpine swift should I continue ?
only 14(C)
ive done the rest
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Hi, can someone help me with this one?
Δyssrupt
do I understand it correctly that it asks me to find a derivative of integral?
ye
how did u come up with this?
uh
I believe u can prove FTC 2 using chain rule
like u know the integral of f(t)dt is a function right?
so let F(x) denote the corresponding functino
to f(t)
integral of f(t)dt
then substitute F(t) with F(u(x))
why u(x) ?
why u'(x) appears there?
this
cuz chain rule
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Find all nilpotent elements of Z/18Z.
in the ring Z/18Z an element is nilpotent if it can be raised to some power and yield the additive identitywhich is 0
Since ( (a + 18\mathbb{Z})^n = a^n + 18\mathbb{Z} ), we need to find all integers ( a ) such that ( a^n \equiv 0 \pmod{18} ) for some positive integer ( n ).
alr so the properties of modular arithmetic, we know that ( 18 = 2 \times 3^2 ). and any element ( a ) such that ( a ) is divisible by either 2 or ( 3^2 ) is nilpotent.
the nilpotent elements of ( \mathbb{Z}/18\mathbb{Z} ) are those elements whose residue class modulo 18 is divisible by 2 or ( 3^2 )
ويسالوني بعشقء مين؟🫨
What is the answer?
I cant provide the answer
We are here to help not to answer
If i tell u i would get banned
What does it mean whose residue class modulo 18 is divisible by 2 or 3^2
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thats correct for f(x_0)
but we stil need f'(x_0) and all the other bits
i assume it wants it as an equation
yes
y0shi
-16/125x+24/25?
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how x can be equal to tan(θ)
where?
It says “x = tan(θ)” not “x = tan(x)”
Which part
I only see two equalitys for x
x=cos(θ)
or
x=cot(θ)
like how x can be equal to tan(θ)
<@&286206848099549185>
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✅
<@&286206848099549185>
@hoary sparrow
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𝐴 = {𝑥 / 𝑥 is a professional soccer team and belongs to Bogotá} 𝐵 = {-4, -2, 0, 2, 4...}
Based on the selected items, the following responses are provided:
According to the selected item, determine by Extension the set given by Comprehension and determine by Comprehension the set given by Extension.
By Extension:
Set given by Comprehension: {𝑥 | 𝑥 is a professional soccer team and belongs to Bogotá}
By Comprehension:
Set given by Extension: It is not possible to define the set by Extension without knowing the specific elements that satisfy the condition given by Comprehension.
Find the cardinality of each of the sets:
Set 𝐴 is undefined in size (a specific list of professional soccer teams belonging to Bogotá is not provided), so its cardinality is unknown.
Set 𝐵 is an infinite set, as the given sequence extends infinitely in both directions. Therefore, its cardinality is infinite.
Identify the types of sets:
Set 𝐴: Infinite (no specific limit on the number of professional soccer teams belonging to Bogotá is specified).
Set 𝐵: Infinite (it is an infinite sequence of integers).
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I've got 2 questions, how would I find a1 for a geometric series that's described? The other one is how would I write and equation for the nth term of a geometric sequence
One example for the 1st question would be Sn = 1550 , n = 3 , r = 5
An example for the second would be 1, 4, 16
xd_senBugha
Which one would this be
well
in geometric sequence
one term divided by the previous term is the common ratio
I'm just trying to figure out how to solve it
you need to find a_1 first right
Yes
plug in everything u know here
Then for the second one need to find the nth term of a geometric sequence
geometric sequences have the form $a_n=a_1(r)^{n-1}$
Jash
Hmm ok
hello need help :c
And n?
!help
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you only need the general term right
Sorry for some reason this is confusing, I'm just trying to make a problem for it
!help
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Setup the equation
So if I just fill this in that would be good for making an equation
For the nth term?
yes
nth term should be in terms of n
What would I write for n in this case
Just n?
So like
yes
1(4)^n-1
nth term just means ur making a formula to get any term
after you fill this in
Which in my case it would be
1550= a_1(5^3-1) / 5-1
I'm sure you know the command and how to make it an image
solve for a_1
i think
1550=31a_1
Ok so I divide the 124/4
ye
and divide by 31 on both sides
50=a_1
Tysm bro
np
Have a nice night
Oh crud
I just stumbled upon another thing
On my worksheet
It's the same thing
Find a_1
But instead if n = ?
It's a_n=?
What do I do here?
I have 2 of these problems with a_n=?
wait can u show the whole problem
$3478.2=\frac{a_1(1-2)^n}{1-2}$
Jash
$a_1(2)^{n-1}=3481.6$
Jash
so this is using the sum
they give a_n=3481.6
you have a system of equations
So I can do this
here a_1=3481.6/2^(n-1)
I'm so confused 😭
so you have this right
mhm
you can divide both sides by 2^(n-1)
Which gets this
and you can substitute that for a_1 in this
yea u will have an equation in terms of n only which u can solve
3478.2=3481.6/2^(n-1)(1-2)^n / 1-2
ye
3481.6/2^(n-2)(-1)^n / 1-2
/ -1*
So would I just put everything in parenthesis and make it negative
Than continue to solve
where did you get n-2
Wait one second
I mightve mistyped
It's n-1*
3478.2 = -(3481.6/2^(n-1)(-1)^n)
Cuz since the fraction is over -1 I can just put it in parenthesis and make it negative
But that doesn't do it cuz 3478.2 is positive
I'm backtracking wtf
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If they didnt give me the information in red that it was centered at 0
How would I determine c?
This is finding for a Lagrange Error Bound
the polynomial shown is the first few terms of the maclaurin series for cos(x), which you are expected to know
note that maclaurin series are taylor series centered at x=0
in any case, for a power series centered somewhere else, you would expect to see (x-c)^n in the way they represent the polynomial
So Taylor Polynomials if not states to be centered at a different value, its always centered at zero?
,w taylor series for cos x centered at x = pi/6
note how the taylor polynomial for any other center would have (x - c)^n whereas if it's centered at 0, it will just have x^n
Ah I see, missed that some how 0_0
ty for clarifying i got it
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Question 8 a, b, and c
Once I figure those I should be able to do the rest