#help-23
1 messages · Page 338 of 1
I don't understand your variable substitutions. Did you use x = rcos t, y = rsin t, z = z?
The limits then, for r would be [-R/h(h-z), R/h(h-z)], t would be [0, 2π], z would be [0, h/2]
No, dxdy jacobi only p
There is no x or y inside the integrals
And t i put -pi/2 to pi/2 because it says x>0
Why do you say r goes from negative? R is the radius so starts from 0
<@&286206848099549185>
Yeah you're right. r > 0 ✓
So why result wrong?
Let me check
The limits (-R/2) to (R/2) is for what?
Shouldn't it be (-π/2) to π/2 if you substituted x = cos t, y = sin t
You should be having $\ \int_0^{h/2} \int_{-\pi /2}^{\pi /2} \int_{0}^{R(h-z)/h} \rho , \cdot \dd \rho \dd \theta \dd z = \frac{\pi R^2}{2h^2} \int_0^{h/2} (h - z)^2 \dd z$
@earnest rain
Arya
This'll give you 7πR²h/48
So what i do wrong?
??
Idek how you managed to send a "z" term to the denominator in line 2
Its a 2
Its h/2
Oh, and what's the limits -R/2 to R/2 for?
Its h/2
Oh
But z limit is from 0 to h/2
Hmm
Its as u wrote
So you're basically getting this in line 2 ig
,rccw
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hi guys!! me again. I really have confusion on how to make a venn diagram for these questions so can someone help me along with an explanation:
which might help me in future examples as well...
You have two sets:
C - Set of sodas that have high amounts of caffeine
S - Set of sodas that have high amounts of sugar
So, in the Venn diagram, you have to draw 2 circles
yes and their intersection is 6
Exactly
so, do I do:
only Caffeine= 8-6 = 2
only Sugar = 12-6= 6
Intersection = 6
6 + 6 + 2 = 14 -> Here is my problem
I think the problem here is that you think that all the 24 sodas have one of the properties, that is, the union of the sets is the total of the sodas
But instead, there are 24 - 14 = 10 sodas that doesn't have either high amount of caffeine or sugar
oh alright, so- can be 10 sodas could be placed in the universal set? like within the box, but outside the venn diagram
Yes :P
ohhh alright thank you so much
you're welcome
now, the next follow up is calculate the probablity that the soda picked at random is high in sugar and but not in caffiene
so in terms of the venn diagram, would I need to calculate only Sugar
or will the intersection count?
That's right!
Nope, because the intersection has sugar and caffeine
And the question wants no caffeine
jee type question
ohhh so it's a part of caffiene which the question doesn't want
@mighty sandal u in 11th?
I'm in 10th lol
oh cool
dream is IIT but...
I'm really messing up in probability, set and venn diagrams
also tysm for your help @frail pumice !!
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Hello, I understand all the working here, but I'm struggling to see why they decided to do the whole thing with u = sin(theta) instead of just using the double angle formula for costheta sintheta?
Is it just a matter of preference? How do I know when I should do the d(sin(theta)) thing?
It's a choice
You can go either way
If you go with double angle formula, you still gotta do a sub
Ah I see, thanks
So presumably once you get good at spotting it it's a useful tool
Yeah it's the best tool
Oh? Do you not just replace it with 0.5sin2theta and then you can integrate that normall?
*normally
You get 0.5 sin 2theta
So then you gotta sub the 2theta with some thing
I mean yeah the sub will not be a long one but still
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I don't understand the logic of f(x+h) how it suddenly becomes f(x+h)^2
it's (x+h)^2
If f (x) = x^2
Then f(x+h) is (x+h)^2
f(x+h) - f(x) / h
we start with this
and i get that f(x) = x^2
so f(x+h) - x^2 / h is also correct
but if f(x) = x^2 why does f(x+h) = (x+h)^2
we are just replacing x with x+h?
thats all we are doing?
putting a different input into the function
basically yes
you can for example think of x+h as a separate variable
to get more clear
no
(x+h)^2 - h?
yeah
hmmm
to get more clear, you can like assume u=x+h and substitute it into f(x+h)
to see what's going on
what about this?
f(h) = h^2 - h
(x+h)^2 - h
what?
just different variable names
not in this same context
imagine it as a new question
i mean what do you want to mean in the last line
in this
i'm not sure lol
just trying to make sense of replacing inputs
the bracket for a function is like a jail
different from regular bracket
don't worry too much it's just change of input variables
f(x) = x^2
f(x+h) = (x+h)^2
hmmmm
interesting
i suppose that makes sense
wow, that's a crapton of work that derivative power rule does so easily for us
to find instantaneous rate of change for f(x) = x^2
hopefully that means you'll appreciate using derivative rules and how much simpler they are
ah OK, i was thinking limits would be used more for understanding correlation between average of secant to slope of tangeant
i just learned difference of squares method by drawing out a 4 piece square today
I would normally use FOIL on that
FOIL prob faster, this looks like way more writing / drawing
but kinda cool to see it done this way
that's equivalent to foil
funny I never saw it explained like this until today
been using it for years now
almost feels like matrix algebra, maybe there is some correlation here
btw, when someone says "Matrix Algebra" and "Linear Algebra", do they both mean exactly the same thing? if so, why the two names?
or would there be subtle differences between both definitions
kinda like perpendicular and orthogonal for example, 99% similar but tiny difference
this has nothing to do with matrices
oh
tables look the same as matrices but have nothing to do with each other and you should just infer from context what it is
Linear algebra is a broad field that studies vector spaces, linear transformations, and abstract mathematical structures, while matrix algebra is a subset of linear algebra that specifically focuses on matrices and their operations, such as addition, multiplication, inversion, and decomposition. Although matrices are a fundamental tool in linear algebra, the latter extends beyond matrices to more general concepts like vector spaces and eigenvalues. The distinction is analogous to the difference between a general theory and its practical computational tools.
or ask
now I gotta look up with "analogous" means
`Analogous means that two things are similar in certain ways, allowing for a comparison between them. They share certain features, functions, or relationships, even though they might be different in other aspects or in their specific nature.
Analogous in Everyday Use: You might say, “A library is analogous to the internet in that both provide access to information.”`
ty @plucky elk - always here to help 🙂
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I can`t understand how to get rid of the root here
This is what I started with :
,, \int\limits_{-\frac{\pi}{2}}^{\frac{\pi}{2}}{\sqrt{\dfrac{64,{e}^{\frac{8,x}{3}}}{9}+2,{e}^{\frac{4,x}{3}}}}{;\mathrm{d}x}
Ulerand
,, \dfrac{3}{4}\int{\sqrt{\dfrac{64{e}^{2u}}{9}+2{e}^{u}}}{\mathrm{d}u}
Ulerand
Now I'm here, also u = 4x/3
notice that 64/9=(8/3)^2
That?
factor out an e^u
or wait
idt this is a perfect square case
so factor an e^u
,, \dfrac{3}{4}\int{\sqrt{{e}^{u}(\dfrac{64{e}^{u}}{9}+2})}{\mathrm{d}u}
Ulerand
Like that?
where did the bounds go
💀
I just didn't write them, anyway first I need to integrate it
Maybe I can split on the two roots it now?
,, \dfrac{3}{4}\int{\sqrt{{e}^{u}}*\sqrt{(\dfrac{64{e}^{u}}{9}+2})}{\mathrm{d}u}
Ulerand
If I could only get rid of the root at all..
Maybe try $v=\sqrt{e^u}$
SWR
If you sub v=e^u, you can follow it up with this
Swr's suggestion might be easier though
Hm, I'll try this first then
Also in this case, $du = 2v/v^2 dv$ ?
Ulerand
,, \dfrac{3}{4}\int{v\sqrt{(\dfrac{64{v}^{2}}{9}+2})}\dfrac{2v}{{v}^{2}} {\mathrm{d}v}
Ulerand
@last falcon Has your question been resolved?
So what about dx? Is it gonna be dx = 4/3 * 2v/v^2 ?
Hm, maybe you are right in this one, yeah
Okay I'll try this substitution in this one
u getting it?
Not really, there still a root that stands in the way
,, \dfrac{3}{4}\int\limits_{-\frac{\pi}{2}}^{\frac{\pi}{2}}{\sqrt{\dfrac{64,{v}}{9}+2,{v}^}}{;\mathrm{d}x}
Ulerand
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
dv right
so like [64/9 v + 2] dv = t?
ah
,, \dfrac{3}{4}\int\limits_{-\frac{\pi}{2}}^{\frac{\pi}{2}}{\sqrt{t}{;\mathrm{d}t}
Ulerand
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
,, \dfrac{3}{4}\int\limits_{-\frac{\pi}{2}}^{\frac{\pi}{2}}{\sqrt{t}}{;\mathrm{d}v}
Ulerand
and $t = 64/9 v + 2$
Ulerand
Why so?
do uk how to convert the limits when u use substitution
Aren't when u change the symbol from + to - ?
no it changes
limits change
but in this case i wudnt wanna change the limits
i wud solve this question indefinetly and then replace the value of t and then replace the value of v
cuz like when we change the limits, it gets uglier
,, \dfrac{3}{4}\int\limits_{\frac{\pi}{2}}^{-\frac{\pi}{2}}{\sqrt{t}}{\mathrm{d 64/9v +2}
,, \dfrac{3}{4}\int\limits_{\frac{\pi}{2}}^{-\frac{\pi}{2}}{\sqrt{t}}{;\mathrm{d} 64/9 v + 2}
Ulerand
https://www.khanacademy.org/math/calculus-1/cs1-integrals/cs1-integrating-with-u-substitution/a/u-substitution-definite-integrals#:~:text=There's actually another thing you,you calculate the definite integral.&text=Remember%3A When using -substitution,for the limits of integration.
check this out and tell me if u understand
what u doin bro?
Well this is explanation of the substitution ?
ye it explains why limits change
Okay, I guess I understand why it changes, tho I didn't really know about this
But as u said, we can just do the indefinetly and then replace it
im having a lil doubt in that cuz when u integrate indefinetly u get the constant C
But the question is how to solve it even indefinetly
u mean definitely?
Well we will replace the value t to v then to x and with old limits we can solve this
no the constant C wud surely make a difference
we will get constants 2 times
since we used substitution twice
Can't I ignore constant ? or what I shall do then
see either we can change the limit twice
or we wud need help from someone else regarding that indefininte integration constant stuff
cuz im not sure waht to o
I never done const in defined integrals, even with the substitution, i just straight igored it and returned value (for example t) to x
even i nvr faced the problem, since whenever i do substition i change the limits and it gets more simplified
I found this method of getting rid of root, but I don't really understand how it coud be. Like were the "2" before the e^u goes with the denominator and what +(0) is
@last falcon Has your question been resolved?
without more context that's wrong. they just disappeared a e^u term
Hmm.. I thought so, then I really have no clue how to deal with this
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how to prove by mathematical induction that a polygon of n sides has n(n-3)/2 diagonals?
@night bay Has your question been resolved?
Its for n => 3 right?
First you have to show that n = 3 is right
yep
what's the next step
Ok, we need to find first a pattern how those diagonals really work
This would serve as our basis
For example,
3 sided = 0
4 sided = 2
5 sided = 5
6 sided = 9
7 sided = 14
Can you see a pattern?
What do you think is the pattern
the only pattern I see is the diagonals have a difference of 2,3,4,5
Thats partially correct but specifically its diagonal of n+1 gon = diagonal of n gon + (n-2)
So we will use this equation to continue our mathematical induction
So suppose k exist such that k(k-3)/2 is the diagonal of a k sided polygon
So we need to show that its true for k+1
So the equation would become (k+1)(k-2)/2
Can you explain this more? I don't get this part
@night bay Has your question been resolved?
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Can someone pls tell me what i got wrong here?
how is that wrong?
Wait i see it
i mixed up the terms lmao
thanks for pointing it out!
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mmmm7
more familiar now?
show work maybe?
2/6 simplifies to 1/3 so i’m guessing you got till $L + 2 = \frac L3$
mmmm7
Is that incorrect
L becomes 6L?
yes
How do you avoid getting a negative answer? It keeps coming out negative
u don’t
because the correct answer is a negative one
That gives me an answer of 1. My thing told me L equals 3
The answer sheet
The question don’t even make sense though
Am I high or does that not make sense
How can L be 6x older than Benjamin and L is 3 years old.
,w L = 6B and L + 2 = 2(B + 2)
this is not what u wrote though
when B was 6 months old L was 3 years old
,w L + 2 = 2L/6 lol
just write it out as follows:
Currently, denote lauren’s age as L and benjamin’s age as B
in 2 years surely their age would’ve increased by 2
so in two years, their ages are L + 2 and B + 2 respectively
now use what your question says to form equations:
currently Lauren is six times as old as benjamin:
L = 6B
in two years, Lauren is twice as old as Benjamin:
(L+2) = 2(B + 2)
then solve those two equations simultaneously
@lean otter Has your question been resolved?
Okay I see. The answer being negative didn’t make sense to me
It still kinda doesn’t not gonna lie
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is coposition of two monotonic sequences monotonic?
Yes,
One can look at the different cases easily
If u is nondecreasing and v is nonincreasing
x ≤ y
u(x) ≤ u(y)
v(u(x)) ≥ v(u(y))
note that it works for any mapping, not only sequences
The composite of two monotone mappings is also monotone.
What a wonderful world!
wait could you please elaborate
why when i plug nondecreasing mapping into a nonincreasing it preserves its momotonicity?
,w graph e^{x^3}
,w is e^{x^3} monotonic
this seems to work
yeah
Consider u and v be monotonic
Either u is constant or nondecreasing or nonincreasing
Same for v
So you have exhaustively 9 cases to study
Study when u is constant, v constant
Then u constant, v nonincreasing etc
I only wrote one of the nine cases, for u nondecreasing and v nonincreasing, but you easily see that the reasoning is similar up to changing the symbol ≥≤=
you first consider any value (or integer for sequences) x ≤ y
You then apply u, then v over this inequality
v(u( • )) is your composite of monotonic
if then v(u( x )) = v(u( y )), the composite is constant hence monotonic
If v(u( x )) ≤ v(u( y )), your composite is nondecreasing hence monotonic
and so on
@trail otter Has your question been resolved?
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It seems wrong…
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PCM problem solving, how do i start solving such problems
the graph:
@merry herald Has your question been resolved?
@merry herald Has your question been resolved?
@merry herald Has your question been resolved?
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can you help me ?
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J ai du mal avec la 4.b
Car comment je peut en deduire ?
@worldly umbra Has your question been resolved?
🙏🏻
it's hard for people to help you if you don't tell them which part you're struggling with
it's also a little hard because not everyone here speaks French
I said
It's 4.b
ah, my bad
Yes you're right
But how can i translate all
okay well, it sounds like you need to verify that $V_n = M^nV_0$?
fallenstars
Yess
okay, part 4a) states that $V_{n + 1} = MV_n$
fallenstars
I'll write a pattern out, and hopefully you can see the reason why 4b is true
Yes it's done
I'll try
\begin{align*}
V_1 & = MV_0 \ V_2 & = MV_1 = M(MV_0) = M^2V_0 \ V_3 & = MV_2 = M(M^2V_0) = M^3V_0
\end{align*}
fallenstars
see a pattern? 
V1 = MV0 comes from part 4a
everything else goes by induction 
no problem 
sure, but I can't promise to be able to answer 
what confuses you?
the problem is claiming that V_n = this matrix for all n in N
I'm not exactly sure what it means to express U_n as a function of n 
Whyy
maybe they want you to write U_n as an explicit vector
like they did with V_n
I'm not entirely sure 
But it's already done?
how is it done? 
why do you think it's already done? 
haha
Becauseeeee
let me read
Yakubros is here to say the day 
haha
matrices sequences
thank you fallenstars for what you've done till here
pour quelle question
La 5.b on nous dit d exprimer Un en fonction de n mais c est pas deja fait??
C est ça que je comprends pas
this was an exercise in my very limited ability to read French 
sorry🙏🏻
I haven't read French properly in quite a few years now
issok 
So It's a good exercise
où est-ce que tu l'aurais déjà fait ?
Bah Un(an, bn)
On la un peu exprimer en fonction de n?
Bah jsp ce que je doit faire
avant tu n'avais pas d'expression de Vn en fonction de n
sauf qu'il te la donne gentillement
Un = Vn + U donc je doit trouver ca en fonction de n?
exactemement
surement que U est de la même forme que Vn
pour pouvoir faire la somme
Petite question bete mais comment sait on que un c est ça
Genre juste en changeant me signe de u
Mais justement la question après ne suis pas
On me dit ma limite de an il y a pas de rapport
on te dit quoi dans la question 4 ?
hereusement
Oui mais on nous donne la suite Vn=Un-U
eh bien ajoute U des deux côtés
A oui
Un = (an, bn)
Mais ça doit etre penilble d exprimer Un en fonction de n
Comment ça ?
Vn + U
Att pour la 5.b?
oui
Avec Un=Vn+U?
Ahaha juste ça?
oui
Aahahah
et après pour la suite c'est assez tout droit
Et la question c ???
interprétation de limite
On a pas deja conclu?
la réponse est une phrase en français où le seul chiffre est la limite de an
oui tu explique ce que veux dire le resultat de la 4b dans le contexte de l'exercice
Oh ok
pourquoi cela devrait être compliqué ?
C est simple alors
J avoue dis comme ça
Merci vrmt 🙏🏻
Tu me sauves toujours la vie
Oui c est dommage
D ailleur ça te prend pas trop de temps pour aider les autres?
quand je sais ce qu'il faut faire non
puis c'est comme je veux si je veux pas le faire je le fais pas
là avec gg trad pour un exo comme ça tu aurais galéré
surtout qu'on a parfois pas les mêmes visions sur les maths
y'a des choses qu'ils font qu'on ne fait pas du tout
et vice versa
ça marche, si tu as tout compris c'est bon pour moi
de même
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Can someone please help me with this question
I thought of writing it out as steps
So for the 1st they could have gotten SSS (Scissor, Scissor, Scissor)
2nd they could have gotten RRR (rock, rock, rock)
3rd they could have gotten PPP (paper, paper, paper)
and 4th they could have gotten SRP (scissor, rock, paper)
I also know that there is a 1/3 chance of either choosing scissor, rock, or paper
but idk how to calculate the chances of losing/winning with this info
So, you know the like
you know the total number of possibilities right
lets just think about 1 round
how many possible outcomes, TOTAL, in a single round?
6 possible outcomes?
cause 3!=6
this seems waayyy too low
it seems like, take some person is first
they can choose 1 of the 3
then for each of those 3 possibilities, the second person can choose 1 of 3
and the same for the third
so for each of the 3, another 3, and then another 3
oh i thought you meant something else mb
so 27 cause 3^3
yea
before you go all the way out
do you know the probability that no one wins in the 1-round case
its not so bad to think out
Well there is a 1/9 chance two players pick the same thing
and there is a 1/3 chance the third player wins
so 1/27?
hope the color comes through
not quite
does the layout of the diagram make sense?
this is a single round
i have a feeling im overloading the diagram
here's circled in blue all the outcomes wwhere no one wins
oh so 4/9?
6/27
You also have to include where all choices are different
lol no worries
so 1/3 chance
yea
it said it was wrong
its not correct as the final answer
its correct for a single round
we need to use more thinking to get to the final answer
right, and were looking at a single match
you dont have to delete anything lol its all good
i should have maybe made it more clear the process i was gonna go through
than jumping right into numbers
It's important to agree that each round is independent, that's the last big thing
I mean, if someone wins some round, that doesnt change the outcome of the next round
it has no influence
yeah so we multiply all of the events up to get the ans
if you win a round of rock paper scissors that doesnt make you more or less likely to win the next round
agreed?
you got it
yeah i agree
,w (1/3)^4
thanks for breaking it down
np
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can someone please help me understand rieman sums and sigma notation
ill type out a specific question give me 1 min
im having trouble expressing it as sigma notation
right now im working on the midpoint
this is my understanding so far
I feel like i can do left ones
And probably right ones
but i keep messing up translating the difference between them
The only major difference between them is exactly what the x_i are
You divide your interval into n(=4) subintervals. The midpoint sum involves evaluating the function at the midpoint of each subinterval
Do you need to?
i need to write the sigma notation for the right left and midpoint
then plug it into a calculator and have the answers
professor didnt teach anything so ive been here for for 5 hours so far tryiung to teach myself
im at the point where i understand the concepts just dont know how to write it
i think
I don't love what you wrote for M but the fact that decimals are included means that there isn't really a clean way to write it
well im not sure if thats right
i dont think it is
cause idk how else to represent that its a different x_n value
its x_0 = 1.5
x_1 =2.5
etc
right
Indeed
so how do i write that as a sigma
$\sum_{i=0}^3 f(x_i)$ with your list of $x_i$s is what I would do
Steakanator
what does that mean
What does what mean
yea but when i plug it into calculator it doesnt work
says its undefined
unless i use 1 and 4
or 2 and 5 etc
Please show me exactly what you're putting into this calculator
i think i need to just start over again ive made no progress in my understanding
I can't stop you but I'm not sure if such drastic action is needed
Once more
so wait if we go back to this one
would you be able to help me understand
how to go backwards from the sigma notation i have
back to the other parts
so i knownwhat part comes from what
Keep this list at the front of your memory
okay
$\sum_{x=1}^4 f(x)$ as you wrote is equivalent to $\sum_{i=0}^3 f(x_i)$
Steakanator
In the first we're moving through each number (which we can do since they're all integers and sigma notation is really meant for exclusively integers). In the second we're moving through each index
The second is f(x_0) + f(x_1) + etc. = f(1) + f(2) + etc. Because x_0 = 1, x_1 = 2, etc.
okay
so can i do it either way
writiing it via the index or writing it via the values
Yes and no
how do I know when to use which
You can do either way in this case because your values are integers separated by 1
The index form is universal
In every case
ok so would you be able to teach me how to go from into the index form
so then i have a method i can apply to any problem
Just read off this
okay 1 sec
okay so for this i see where the zero is coming from
why is it three should it not be 4
cause its looping through 5 different values
from index 0 to 4
You're only covering left endpoints in that example
x_4 is the right endpoint of the 4th subinterval
so there is only 4 parts
that hit
on the left side
which indexes are those?
indexes 1 through 4?
indexes 0-3
Those are the right
are the left
0-3 are the left
Not for the left sum
Having i as your sum index but x in the summand is bad form
You need your variables to agree
so it should be 4/i+3?
If you're summing through values of i then you need something involving i within your summand
Sure
There should normally be brackets around 4/i + 3, but since deltax is 1 it technically doesn't matter this time
ok
so now giuve me 1 second to write soemthign
Okay so now for this problem
to find the right left and middle
it would be this
correct?
cause same interval and n still = 4
so numbers should be the sam,e
for the left and right
You really need to write the variable you're indexing through at the bottom of the sum
okay
Because for L you've written the correct numbers for i, while for R you've written the equivalent values of x
wdym]
how can you tell
is the index not 0 --> 5?
No
That is x
Sure
x is going from 1-5
i is going from 0-4
so it should be like this
WAIT
it should start at 1
left excludes the last one
right excludes the first
so then how do i do the middle one?
You need a different list, most simply
so it would be th9is right
left hand is the red
right hand is the blue
left side is the values right side is the index
but idk what to do for midpoint
would be this right
?
wait no it would be shifted down by one
starting at 0.5
is this correct?
0.5 is not the midpoint of any subinterval
okay so the first one i had was correct
im just subtracting the left from the right yeah
@rigid inlet im looking for the index values of those right?
sorry im just really struggling to understnad
been working for hours
Sorry I have to go, good luck
Closed by @lapis breach
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✅
Break [1,5] into 4 parts.
Report back the center of each part
because n=4?
The 4 parts are
[1,2] [2,3] [3,4] [4,5]
Their centers are
1.5, 2.5, 3.5, 4.5
Note that n + 0.5 gets those points, for n = 1,2,3,4
which is the right one
f(n + 0.5) is the height of each rectangle
1×f(n + 0.5) is the area
Where f is x² + 3 in this case
so are those generally true for all cases?
But, imo, if you're struggling, do it without sigma notation at first
i need to do it with sigma
because my professor told me to
she "taught" us integrals, sigma notation and this shit in 30 minutes and expected us to understand it all
Right. You definitely should work your way up to sigma notation, but it's a lot to learn all at once
I just straight up dont have time
class is so fast paced for no reason
but what do i do for the sigma cause it cant be 4 and then i=1
because thats already the R
right one
and it cant be 3 and i=0
and it cant be i=0.5 and 4.5
cause appearently you cant use decimals
]
would this work
cause its the same as the LEFT one
but every i value is 1/2 higher
@stoic dune
ok so that is correct except it is 4 and 1 for some reason
great now i gotta figure out how to do it with a table
cause that didnt take me long enough
First, identify the points. Which values of x are we sampling from?
There's a table of 11 values there. We're going to use 10 of them
The process is similar to this
we will be using the first 10 for the left
and all but the first value for the right
correct>
so is this correct? formatting wise?
im trying to make sure i understand sigma notation
That is a way to write 1 + 2 + ... + 10 in sigma notation
ok awesome
This question is all calculation, and sigma notation won't be very helpful for this one
Wait sorry, you want to write i, not xi
why
cause isnt i referring the the index
and x is the value associated with the index
i is the value, 1, 2, 3...
xi is some value that depends on i
so for every value of i there is an x
i is the index value no?
x is the value that we actually care about
right>
the area under the curve
xi is going to be the "sampling point". Left, midpoint, or right, depending on the question
okay so i just found these formulas from my professor what is the difference between this and what ive been doing? Would it be easier to judt plug and chug using these for each type?
No difference. Use which you feel more confident with
this might be whats not making sense to me
i was under the impression that we have
x_i
x_0=1
x_1=2
x_2=3
x_3=4
x_4 = 5
okay ill just contine what im doing cause i dont get thi
For the example above,
x1 = 0, x2 = 0.5, x3 = 1...
It's where we "pin" each rectangle
where each rectangle hits the graph
at the left mid or right point
right>
would you be able to walk me through setting this one up
so i can just know how to do it and can relicate that for future cases
@lapis breach Has your question been resolved?
no
@lapis breach Has your question been resolved?
Hello <@&286206848099549185> im working on trying to put this table of values into sigma notation so i can become more familiar with it. Ive gotten to the answer without it for this problem but using the formula above how do i get those values to put it in notation
my k value would be 0
my n value would be 10
delta x = 0.5
i believe those are correct but where do get the orther values
Would this be as far as i can get without plugging in all the tables values in for a because im not explicitly told what f(x) is?
well actually now ive just got to express sums in sigma notation regardless
i guess id want to start by finding deltax
which is 2
me before scrolling up knows whats going on
a is just n+2
b is just n+4
c is just n+7
d is just 1/nx(n+1)
or am i suppose to explain it idk
@lapis breach Has your question been resolved?
aaaaa
can u exolain how to do these
wdym
these?
yeah so R_L I presume is the left Riemann sum. So can you write the problem in this form?
yep
i know how to get the k value and the n value obviously deltax is b-a/n but what is a
oh i see
starting point
yep
oh ok
thanks
im just so tired been doing calc fr 11 hoirs
i shjould have been able to figure that one out
no worries, takes a bit to get the hang of it...
yea its hard cause my professor desnt actually teach us anything
so i gotta teach myself all of it
if you practice enuf times it'll come easy as it's not hard just need to get familiar
understandable
cause im learning integrals sigma notation and rieman sums at same time
and they all build off eachother
yep
for this its just do area of square + triangle
and do that for all the sections
that it asks for
displacement = area under velocity curve right
yes

