#help-4

1 messages · Page 30 of 1

analog schooner
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Its fine

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I can read it

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Without spaces

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$\epsilon_n \to 0$

rocky lotusBOT
analog schooner
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Yes

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Wait you're right

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Its not 0 × infinity in the first place

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I made a mistake

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Thank you

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Both of you

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Yeah

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Thank you

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I thought it was 0 * infinity instead of 0 ^ inf

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That's why I thought it couldn't be ignored

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👍

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.close

vale dockBOT
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river shale
vale dockBOT
river shale
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@versed quarry post your problem here

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Nvm, you claimed one

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.closed

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.close

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river shale
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No, you’ve already claimed a channel

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I don’t have one

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I claimed this for you

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Nah, it’s alr

vale dockBOT
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icy sigil
icy sigil
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i need it for its endpoint to be $(x,i\cdot y, i\cdot z)$ where y and z are coordinates of the beginning of the vector

rocky lotusBOT
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maxtsg

icy sigil
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and in this case x is just 1

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since desmos doesnt accept imaginary vectors i just swapped the coordinates and flipped a sign since a+bi * i = -b+ai

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but it didnt work i think

vale dockBOT
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@icy sigil Has your question been resolved?

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lavish tinsel
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So the test says it should be impossible, but I think x²=3-5/3x⁴-2x⁵
x³=3+2x¹-2x⁵
Am I dumb or is that the real answer?

charred burrow
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if you have five variables and only four equations, you can't have unique solutions for the system

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i.e. there are infinitely many solutions

lavish tinsel
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Its general solution to the basis to the x² and x³

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cedar spear
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Hi, I neeed someone to explain me this.

i'm learning riemann sum and a teacher wrote this

If f:[a,b] -> R and P, Q partitions of [a,b], and P ⊆ Q, then

S(inferior)(f,P)=<S(inferior)*(f,Q)=<S(superior)(f, Q)=<S(superior)(f,P)

and he said it was bc if A ⊆ B, then inf(B) =< inf(A) =< Sup(A) =<Sup(B)

it doesnt get on my head bc i think the signs (=<, =>) should be inverted, and I need someone to explain me why does this work this way

Thanks

ruby sleet
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so B is the only one that can potentially reach further down

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similarly, no matter how far up A reaches, B will reach too

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so B is the only set that can potentially reach further up

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as a small example in terms of intervals

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A = [-1,1]

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B = [-2,2]

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A ⊆ B

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A is a box contained in B, a bigger box

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the bigger box goes further down and further up

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no matter how big the small box is, the bigger box must, by definition, be bigger

cedar spear
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but then what my teacher wrote shouldnt be

s(inf)(f,Q) =<s(inf)(f, P)=<s(superior)(f,P)<=s(superior)(f,Q) ?

ruby sleet
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oh wait actually

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It does work the way it's originally written

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when you have a partition made up of more subsets

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then each subset is individually smaller

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that's how you have to interpret it

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if P ⊆ Q, then take one subset in the partition P, call it B

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then it's either gonna appear as is in the partition Q

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or it's gonna be divided into smaller sets, call them A1,A2,...,An

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the part of the inferior and superior sums for P that is linked to B will be length(B)*inf(B) and length(B)*sup(B)

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whereas the terms that correspond in the partition Q will be length(A1) * ... + length(A2) * ... + ...

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because inf(B) <= inf(A1), inf(B) <= inf(A2), ...

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we will have length(A1) * inf(A1) + length(A2) * inf(A2) + ... >= [length(A1) + length(A2) + ...]* inf(B) = length(B) * inf(B)

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same thing for superior sums

cedar spear
ruby sleet
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I'll try again

cedar spear
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thanks

ruby sleet
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btw are partitions for you any kind of sets or are they just points that separate intervals?

cedar spear
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sets i think

ruby sleet
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ok

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what it means for $P\subseteq Q$ in terms of partitions:

If $B\in P$, then you can find $A_1,A_2,...,A_n\in Q$ such that $B = \bigcup_{k=1}^n A_k$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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I just wrote what it means mathematically

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if B is a set in the partition P

cedar spear
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uhm sorry is that U a summatory?

ruby sleet
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it's a union

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B is exactly the union of some subsets in the bigger partition Q

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Q is a "finer" partition than P

cedar spear
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okay

ruby sleet
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makes sense right? It should be your definition

cedar spear
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yeah, never read it that formal but it makes sense

ruby sleet
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ok

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let's focus on the inferior sums for now, superior sums will be analogous afterwards

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what's your notation for "length" or volume of a set?

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so I can be coherent with what you have

cedar spear
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how many elements it has in

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like A = {1,2,3}, its lenght its 3

ruby sleet
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uh no, like [a,b] has length b-a

cedar spear
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oh alright

ruby sleet
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what's the symbol for that length

cedar spear
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maybe i got confused cause english isnot my first language

ruby sleet
cedar spear
ruby sleet
cedar spear
ruby sleet
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really? how did you define inferior and superior sums then xdd

cedar spear
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wait let me see if i can send you a pic

ruby sleet
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xddd

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ok, but have you ever seen mathematical definition of those

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like S*(f,P) = ...

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anyways

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I'll write $\lambda(C)$ the 'length' of set $C$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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for example $\lambda([a,b]) = b-a$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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are you ok with that notation?

cedar spear
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on the superior sum is the same as inferior but instead of inf it says sup

cedar spear
ruby sleet
cedar spear
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i thought sets were intervals

ruby sleet
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nevertheless, we can continue with the general case

ruby sleet
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not all sets are intervals

cedar spear
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ohh i see

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sorry abt that

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i will get better at math vocabulaty on english

ruby sleet
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now, for any partition $R = {x_0,...,x_n}$ of $[a,b]$, the definition of the inferior sum of $f$ on $R$ is $S_{inf}(f,R) = \sum_{k=0}^{n-1}(x_{k+1}-x_k)\inf_{[x_k,x_{k+1}]}(f)$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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good?

cedar spear
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good

ruby sleet
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so now

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take $P\subseteq Q$ partitions of $[a,b]$.

rocky lotusBOT
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Raphaelisius Maximus MMIII

cedar spear
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yeah

ruby sleet
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so for example, if we take x_0, x_1 in P

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that might become $x_0,y_0,y_1,...,y_m,x_1$ in $Q$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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so I can divide $B = [x_k,x_{k+1}]$ into $A_1,A_2,...,A_m$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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so while in $S_{inf}(f,P)$ we'll find the term $(x_{k+1}-x_k)\inf_{[x_k,x_{k+1}]}(f)$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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in $S_{inf}(f,Q)$ it will be replaced by the terms $Length(A_1)\inf_{A_1}(f)+Length(A_2)\inf_{A_2}(f) + ...$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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does that make sense?

cedar spear
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some

ruby sleet
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ok

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we can go back to this if it's still unclear

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now, we'll look at those two facts

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Fact n°1: $Length(A_1) + Length(A_2) + ... = Length(B) = x_{k+1}-x_k$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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that's just stringing up every "small" subset back together, it makes the big set again

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Fact n°2: since $B$ is a bigger set than $A_1,A_2,...$, then $\inf_B (f) \leq \inf_{A_1}(f)$, as well as $\inf_B (f) \leq \inf_{A_2}(f)$, etc.

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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so

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$Length(A_1)\inf_{A_1}(f)+Length(A_2)\inf_{A_2}(f) + ... \geq Length(A_1)\inf_{B}(f)+Length(A_2)\inf_{B}(f) + ...$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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that's exactly $Length(A_1)\inf_{A_1}(f)+Length(A_2)\inf_{A_2}(f) + ... \geq Length(B)\inf_{B}(f)$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
ruby sleet
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we effectively get something larger than before

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adding up larger stuff will result in a larger total

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so $S_{inf}(f,Q)$ is larger than $S_{inf}(f,P)$

rocky lotusBOT
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Raphaelisius Maximus MMIII

ruby sleet
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$S_{inf}(f,P)\leq S_{inf}(f,Q)$, what was expected

rocky lotusBOT
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Raphaelisius Maximus MMIII

cedar spear
ruby sleet
bronze moss
ruby sleet
rocky lotusBOT
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Raphaelisius Maximus MMIII

cedar spear
bronze moss
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here is a graph of the area S_inf(f, P) we are calculating for a function (in red) and a partition P (in green). And here is the graph of the area for a refinement Q: S_\inf(f,Q)

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you can sort of see why S_inf(f,Q) would be larger

cedar spear
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yeah

bronze moss
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intuitively, refinement -> S_inf and S_sup gets closer to the actual "area" of the function

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so it is natural to expect S_inf and S_sup to get closer for Q than for P

cedar spear
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yes

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but i still dont get why S_inf(f,P)=< S_inf(f, Q)

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i can only see it the other way around, since Q is larger than P

bronze moss
cedar spear
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only the = part

bronze moss
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cuz the example I gave: purple >green

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P={0, 0.5, 1} and Q={0, 0.2, 0.5, 0.8, 1}

cedar spear
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sorry, i dont get where S_inf(f,P)< S_inf(f, Q)

bronze moss
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here is the partition Q marked in orange

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and the partition P

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green area represents S_inf(f,P) and purple represents S_inf(f,Q)

cedar spear
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oh yes I think I got it now

bronze moss
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extra values is really giving it an extra chance to take higher values than the current infimum

cedar spear
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so is S_inf(f,P)< S_inf(f, Q) because A(S_inf(f,P))<A(S_inf(f,Q))?

bronze moss
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well S_inf(f,P) is precisely the area

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ie S_inf(f,P)=A(S_inf(f,P))

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because if you check your formula it is "length times height" over all the rectangles in your partition

cedar spear
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thank u so much

bronze moss
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np

cedar spear
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thank u both

bronze moss
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and you can see why sup is smaller right?

cedar spear
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i got it now i could kiss ur brains

cedar spear
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?}

bronze moss
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extra values-> extra chance for the supremum to be smaller

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if you get what i mean

cedar spear
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since Q is more precise, it wont be so far away from the function, so its area wont be so large

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THANKS

bronze moss
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finer the partition, closer to the area

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sup is over estimation, and inf is underestimation

cedar spear
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thank u

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if i graduate i will write ur names on there

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have a great daay

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.close

vale dockBOT
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bronze moss
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u too

vale dockBOT
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cosmic crest
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integral e^3x times sinx dx

vale dockBOT
cosmic crest
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needs IBP I think, wanna use DI method but idk

coral dragon
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Are you familiar with the horse shoe method? Indeed, that method comes from the DI method.

coral dragon
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So do the first two steps of the DI method, and you'll notice that you kind of end back where you started. That allows you to have a relation with some fudge factor, which is the solution.

cosmic crest
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I know this

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for DI method, you go until 0, until row is integrable, or you end up at the same spot as you started excluding the signs for that row

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I don't think you ever end up where you started with this problem

glass kelp
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It won’t go to 0 here

cosmic crest
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yeah that part is clear

glass kelp
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But it’ll repeat

coral dragon
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Yes, that's what I meant when I said kind of. Your second case is relevant.

cosmic crest
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e^3x will just continue 1/3e^3x 1/9e^3x etc

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so ur never gonna end up back at e^3x

coral dragon
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But you can factor out the fraction.

cosmic crest
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ah

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okay so ig you end up with

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$$
\frac{\sin x}{3} e^{3x} - \frac{\cos x}{9} e^{3x} - - \int \frac{\sin x}{27} e^{3x} , dx
$$

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I think

rocky lotusBOT
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Paul04

fickle rose
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/27? pandathink

cosmic crest
coral dragon
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Without checking if the math is right, you would have that whole expression equal to the original integral. So combine the two integrals (bring that one to the other side) and you'll have the solution.

cosmic crest
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OH I think I remember that from somewhere

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lemme send my work 1 sec

fickle rose
cosmic crest
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OH

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you gotta use the row 🤦‍♂️

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not the diaganol

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right?

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ignore the stuff on the right

coral dragon
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For the last step if the DI method isn't zero'd, yes you have to use the row rather than the diagonal.

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So you seemed to have done a step too many, sorry soldier.

cosmic crest
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so how should I move it over I ended up with 1/9 * the integral

coral dragon
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Bring the 1/9 to the other side.

cosmic crest
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yeah

coral dragon
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Also you should have a 1+1/9 then, no?

cosmic crest
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uh

coral dragon
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Since the original integral plus the 1/9 * integral, so that's (1+1/9) * integral, unless that's what you meant.

coral dragon
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So you moved the 1/9 * integral to the left side, which already had 1 * integral

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So that's 1/9 * integral + 1 * integral = (1/9 + 1) * integral

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Then you can bring that (1/9 + 1) to the left side that you drew, so now you have just the integral in the right side == the solution.

cosmic crest
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moving the integral out is just doing 1 * 1/9 no?

coral dragon
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So you have "... - (1/9) * F(x) = F(x)", which becomes "... = (1/9) * F(x) + F(x)", agreed?

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where F(x) is the original integral, for easy notation.

cosmic crest
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oh ur moving it over

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why is 1/9 pos on the right side tho

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is my double negative = pos wrong?

coral dragon
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Well to bring a left negative to the right, you have to add both sides by its positive.

cosmic crest
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well yeah but the 1/9 is pos unless I screwed smth up

coral dragon
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a - b = c ==> a = b + c

cosmic crest
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yeah yeah fs but 1/9 is pos on my end look at the pic

coral dragon
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Oh I see what you meant,

cosmic crest
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I went off integral udv = uv - integral vdu

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and the row had -sin

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so I thought the - from the formula with the - from the sin would make pos

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but idk

coral dragon
# cosmic crest

When you do row multiplication, you have + -sin(x) * (1/9) * exp(3x), so it should be negative.

cosmic crest
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maybe I'm thinking of this all wrong, sorry if that's the case

coral dragon
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I'm not sure what you mean by the IBP formula. IBP == initial boundary problem?

cosmic crest
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integration by parts

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it's DI method essentially

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ok so ur saying it's neg let's just go with that forget what I said

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so we end up with 10/9 integral

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then move that over to the left and it's gg?

coral dragon
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anyways,

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Yep

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You may need a +C factor, I believe.

cosmic crest
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right

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okay so lemme see ig final answer is

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$$
\frac{9}{10} \left( \frac{\sin^3 x e^3x}{3} - \frac{\cos x , e^{3x}}{9} \right)
$$

coral dragon
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Btw, any particular reason you integrated the exponential instead of the other way? Should yield the same either way.

rocky lotusBOT
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Paul04

cosmic crest
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for u

coral dragon
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What is LIATE? I fear that's another region-dependent concept.

coral dragon
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Interesting, thank you.

cosmic crest
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is my asnwer correct?

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idk if it is

coral dragon
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$$\frac9{10}\left(\frac13\sin(x)-\frac19\cos(x)\right)\exp(3x)+C$$

rocky lotusBOT
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Ordinary

cosmic crest
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oh yeah idk where the cubed came from

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nice!

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tysm for the help it!

coral dragon
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Np, and if you ever want to verify Desmos is a quick and dirty way.

coral dragon
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One moment as I verify this actually..

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Desmos is a free, light-weight website for graphing.

spark burrow
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I haven't heard of the DI method actually

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Is this how you multiply?

cosmic crest
coral dragon
spark burrow
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Yeah, shortens IBP quite a bit, nice notation

cosmic crest
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like what u did

coral dragon
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Oops, replied to the wrong message.

cosmic crest
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I'll try that next time around. thanks again for the help!

#

.close

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#
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gaunt fog
#

Help

vale dockBOT
gaunt fog
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I dont understand how this became

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-1 = i

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Mb from handrwiting

river shale
rocky lotusBOT
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e4 e5 Qh5 Nc6 Bc4 Nf6 Qxf7#

gaunt fog
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Ye

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Like how that happen

river shale
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It’s a definition

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Just like how we decide the definition of sine

gaunt fog
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Idk whats sine

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But says here they square root 17

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I mean

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19

coral dragon
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Like how pi = 3.1415...

gaunt fog
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Ohh i thought Negative - 1 came from the square root of 19

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But i remember my teacher squaring the negative number then simplified it

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How u do that

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19 for example

gaunt fog
river shale
turbid summit
#

mathematicians wanted solutions to $x^2+b=0, b>0$ so they named $i$ as a number that has the property that $i^2=-1$ 🤔

north walrus
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$\sqrt{-1}$ \underline{is} $i$

rocky lotusBOT
#

parabolicinsanity

turbid summit
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i think the actual definition for it is i^2=-1 rather than i =sqrt(-1)

coral dragon
river shale
coral dragon
coral dragon
# river shale Why

Since if the definition was i^2=1, then -i also satisfies that so then -i = i.

turbid summit
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eh i'm not sure but that's what i remember reading

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anyways

river shale
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Doesn’t make sense at all

turbid summit
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well the square root doesn't give one value

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or something

coral dragon
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There's a difference between satisfying, and being defined (precisely) as heh

coral dragon
gaunt fog
#

Alright guys thanjs

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.close

vale dockBOT
#
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neat crag
#

Hey in algebra 2 rn doing logorithms how would i go about solving this question

coral dragon
#

Do you remember what the difference between "f(x)" and "f(x + a) + b" is? (recall shifts)

neat crag
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yea

coral dragon
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Could you explain what the difference between what "a" does, versus what "b" does?

neat crag
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b is vertical shift and a is horizontal

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so

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b movees

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up and down

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a left and right

coral dragon
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Exactly,

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So we want to move the blue curve to the left (by how many units?), and up (by some amount)

neat crag
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left by 1 units and up by about 4?

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so

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is that just it?

coral dragon
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Close, we now need to express g(x) as a function of f(x) (so plugging in for a and b into f(x-a)+b)

livid abyss
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.

neat crag
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g(x) = log(x +1 ) +4?

coral dragon
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Yeah, that's it.

neat crag
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oh that was simpler than i thought thanks for the help

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.close

vale dockBOT
#
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velvet prairie
#

whats 1/2-4.6=
I got 6.765

coral dragon
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pine prairie
#

I once again need some help with pdes

pine prairie
#

The question is to solve u_x + u_y + u = 0, and how I might solve this via method of characteristics

#

The problem is that I don’t really get what the goal is for picking a suitable coordinate transform is, and how I might go about picking it

vale dockBOT
#

@pine prairie Has your question been resolved?

vale dockBOT
#

@pine prairie Has your question been resolved?

north walrus
#

-# i think you can ping helpers if you want

#

-# it's already 15 mins

#

-# gl i havent learnt pdes

vale dockBOT
#

@pine prairie Has your question been resolved?

odd garnet
#

we want to pick a suitable coordinate transformation such that our pde turns into an ode

#

recall by the multivariate chain rule that if we have a coordinate t=t(x, y)

#

then du/dt = du/dx dx/dt + du/dy dy/dt

#

here we want that to look like u_x + u_y

#

so we wanna try smth like dy/dx = 1 if that made sense

odd garnet
#

i mean if you have a pde of the form function * u_x + function * u_y

odd garnet
vale dockBOT
#

@pine prairie Has your question been resolved?

rigid trench
#

lol long time

coral dragon
#

So worked out, this is what I find.

pine prairie
#

I pick a linear transformation?

#

Why linear?

coral dragon
#

It's what I was taught, the answer is "because it's simple, and it works".

pine prairie
#

As in, does linear always work?

#

And what does “suitable” mean?

coral dragon
#

As long as the determinant is non-zero. This doesn't guarantee that you'll simplify the problem.

coral dragon
pine prairie
coral dragon
#

In this case, because the problem you gave was quite linear, it works perfectly. If you did something nonlinear like f(x,y)u_x+u_x^2u_y+u=0, linear wouldn't work.

coral dragon
#

So I chose those values to cancel out the partial beta terms and make the partial alpha terms add to unity.

pine prairie
#

I mean any non 0 det matrix will be a bijection and hence a valid change of basis

coral dragon
coral dragon
#

It's all about reducing the dimensions, which is doable because it's linear.

#

You could alternatively choose to cancel alpha and put beta to unity, you will get the same answer. Otherwise you did something wrong.

coral dragon
vale dockBOT
#

@pine prairie Has your question been resolved?

wise jasper
#

i really need help guys, im having a test tmr
supposedly speaking if i had two planes that were perpendiculared on the same line, would the distance between the two opposite apexes to the two opposite planes equal each other
english is not my first language so this could be a little hard to understand
hopefully you guys can help me

verbal badger
#

!occupied

vale dockBOT
#

Someone else is already using this help channel. If you need help with a question, please open your own help channel/thread (see #❓how-to-get-help for instructions).

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worldly shuttle
vale dockBOT
worldly shuttle
#

Drawing the flow chart only

deep fjord
#

@minor socket

wraith heart
vale dockBOT
deep fjord
#

?

wraith heart
#

doesn't matter go dm him not in a helper's channel

deep fjord
#

why

#

how’s a helper allowed to do ts

wraith heart
#

stop spamming OP's channel

deep fjord
#

?

#

he’s not gonna let you hit

cerulean maple
#

uuuuh.... hi

#

im Jasmine

wet bramble
wet bramble
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#

@worldly shuttle Has your question been resolved?

vale dockBOT
#

@worldly shuttle Has your question been resolved?

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hushed kayak
#

waitm thats possible?! i suddenly have a reason to learn lambda calculus

timber echo
#

so we figured out 2 things that work

hushed kayak
#

im only barely know that lambda calculus can write stuff in a weird way, so i dont understand any of what you did
but, does it make tetration easier to solve, or just translate it to a physical form?

hollow dragon
#

can someone explain function

hushed kayak
#

based

final adder
timber echo
#

if you know how to do anything in lambda you can be handed a huge equasion and solve it without knowing whats happening
bc simplifying/solving it is always the same step

#

ok soooooo

#

the text form translates to the diagrams

#

say i have this function
λG.G

#

like plus or times
λv.v is a function
doesnt matter what letter it is

#

then we have the input, lets say its BANANA instead of a number

#

λv. says "OKAY, find all instances of v, and replace it with the input"
so λv.v banana = banana

#

THATS LITERALLY IT

#

@hushed kayak you following?

#

you can make more complicated equasions to do more complicated things

#

λF.F is just the simplest

#

say um
λx.λy.λz. x (y z)
is a times function
so say i want 5x3
λx.λy.λz. x (y z) 5 3
5 being the first input, and 3 as the second

#

you replace x with 5, and then replace y with 3, and then simplify more but that requires knowing how to express numbers in lambda and i didnt explain that
the drawings make a lot more sense

sharp whale
#

you gotta mention also that numbers and true/false take on something weird for lambda calculus

#

for lambda calculus, everything should ultimately just be in lambdas, so numbers are really some specific lambdas in disguise

timber echo
sharp whale
#

that doesnt give me a nice way to follow up

timber echo
#

idc

#

this isnt about you

sharp whale
#

thats a bit hostile, you dont have to say things like that

#

lets not point things towards me this fast

sharp whale
#

so if you try doing 3 f x, the result is f f f x, or the result of applying f to x three times

timber echo
#

bc f f f x ≠ f (f (f x))

sharp whale
#

by default, you dont need to, parentheses weirdly go right-to-left

timber echo
#

you expressed function f with 3 inputs

sharp whale
#

so f f f x defaults to f (f (f x)) instead of ((f f) f) x

timber echo
#

and id appreciate it if you would stop inserting yourself into my affairs

sharp whale
#

nicole this question isnt specifically about you, its about me adding to an explanation on lambda calculus with more details

#

if someone did this to me, I would assume they are elaborating

timber echo
#

(function) 5 4 6 2
is the function with 4 inputs
the () changes things

sharp whale
# timber echo youre very wrong

Ive checked and yea, by default its left-to-right
the post I took this from left the parentheses out, got it mixed with function composition

timber echo
#

its not( 5 of 4 6 2), put into function

timber echo
#

oh my god this is so badic

sharp whale
#

ok now for true/false

the interesting part here is that true is "take in 2 inputs, then output the first"
and false is "take in 2 inputs, then output the last"
they dont act like the usual true/false

hushed kayak
#

i suddenly dont regret doing computer science

timber echo
sharp whale
#

nicole I am aware that you watched the same video I do

timber echo
sharp whale
#

Ive made an egregious error, but after this its not necessary to tell me the same information again

#

I didnt imply youve only watched the video, just that the video is very good

timber echo
#

im

sharp whale
#

thats alright, we can move on from this

sharp whale
#

function composition acts right-to-left, so I mixed them up, is what this message means

timber echo
#

im sorry its just i see someone doing something that ammounts to 1+5 = 5 and ive had 4 shots of coffee and like no food

sharp whale
#

its alright, it happens to me just as easily

#

Ive been in your position several times and did not calm down

#

the important thing for me to see is to think: dont attribute it to malice, attribute it to a typo

#

in this case its a pretty strong typo and Im honestly not happy with having made a mistake like that

timber echo
#

and the sqrt5 equasion isnt fun anymore bc of you so thers that going on and you intervene to me explaining this telling me im not doing it right while doing this and now im like a pissed twitter black supremacist getting pissed that someone said hi

sharp whale
#

its just that theres effective and ineffective approaches

timber echo
#

im not mad at you over this anymore bc its been cleared up

sharp whale
#

and from my perspective, Ive seen that kind of approach enough to know it wont lead you to anywhere fruitful

timber echo
#

and i have like so much energy and no energy and o7r8o67e5i676o8pguopuo

#

[

sharp whale
#

Im sorry nicole

#

number theory questions cannot be answered with continuous algebra, until you get to complex analysis

#

even then I have no idea how they pull it off

#

until then, we have modular arithmetic and diagonalizing matrices to justify particular behaviors, enough to answer the question

timber echo
#

@hushed kayak im sorry

sharp whale
#

you dont have to get into that, we can focus back on the lambda calculus

timber echo
#

explaining the false and true function is important tho simply bc its confusing and the main resource for lambda does a garbage job at it

#

its really simple tho

sharp whale
#

yea, have you seen an if statement? it looks like this

timber echo
#

just misleading

hushed kayak
#

im trying to find a formula for continuous tetration, so i probably wont get much out of this, will I?

sharp whale
#

continuous? theres many sources about attempting this

timber echo
sharp whale
#

its more of "if P, then A, else B"

timber echo
sharp whale
#

what a true does is select A
and what a false does is select B

timber echo
#

well tetration funtions

hushed kayak
sharp whale
#

yep, thats the idea

timber echo
hushed kayak
#

2^^1.5

timber echo
#

idk how to express a fraction in lambda nor if it can be done but probs not

timber echo
#

do that

#

perfectly

#

but idk if the expression of fractions is possible

sharp whale
#

and at least, lambda calculus isnt going to help you out for these sort of continuous functions

timber echo
#

yeaaaaa

#

its like base 1

sharp whale
#

lambda calculus is more for showing that yes, its possible
its just not very convenient

timber echo
#

so the number 30 is huge

sharp whale
#

111111111111111111111111111111

timber echo
#

here ill show

sharp whale
#

for reference, division alone is messy

timber echo
#

these are 0 through 5

#

ignore the things at the bottom this is just my note sheet

timber echo
timber echo
#

this is partioally why lambda isnmt helpful for tetration

hushed kayak
#

still cool

timber echo
#

that and itl take longer to do the steps

sharp whale
#

and also to consider fractions and somehow implement that

timber echo
#

yea idk i think its too objective and solid to have fractions be a thing

#

but i know not

sharp whale
#

too low-level is the usual phrase

#

there are other approaches than lambda calculus to create a continuous tetration function
granted, you should also learn lambda calculus too regardless

#

low-level for "the parts you are given are too basic, too small to make something of this complexity without grouping things together"

#

theres a research paper on a tetration function, I can try and find it

timber echo
#

i mean we are working with the physsical manifestation of the concept of the number 1 soooo

timber echo
#

i mean makes sense duh

#

but yea

sharp whale
#

I remember the paper, theres a picture of them generalizing it to complex numbers

#

at least I remember the graph

#

not very readable

#

the general idea is that you can consider a specific tetration function F(z) = b^^z

#

F(z + 1) would be including one b in the "power tower" so thats the same as b^F(z)

timber echo
#

ive found ppls note sheets online that contain functions
and ive never found a function that gives a smaller output that actually worked to any capacity

#

i know that they dont usually work with small numbers, im speaking in spite of that

sharp whale
#

I think I know what this table can tell you

#

this is from the paper, and from their guess at a continuous tetration function

#

the upper-right table for example lists 2^^0, 2^^0.1, 2^^0.2, ..., 2^^1

#

similarly for the 3/2, e, and 10 tables

#

they admit their approach will not work if the base is < e^(1/e) which is about 1.445

vale dockBOT
#

@hushed kayak Has your question been resolved?

vale dockBOT
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willow arch
#

can unbiased estimates be decimals

vale dockBOT
willow arch
#

unbiased estimate of population mean

stark wedge
#

yes of course? why couldn't they

#

the population mean of whatever quantity can be a decimal even if individual observations of it are only integer-valued

willow arch
#

oh ok tysm i js thot population would mean counting people but we cant half a person lol

sharp whale
#

if you randomly toggled or not toggled a light then looked on it, the average brightness is between dark and lit
you can estimate this average and itll also be between dark and lit
doesnt necessarily mean how bright that average is means anything concrete, youd have to be more abstract about it

willow arch
#

ohh alrights thank u

#

whats the difference betw sample mean and population mean? or can it be the same thing

sharp whale
# willow arch whats the difference betw sample mean and population mean? or can it be the same...

calculating the mean across the entire population is pretty hard, youd need to ask everyone so that you can get their values to average
because of this, you only choose a random portion of them for a sample, for the easier-to-calculate sample mean

if you did multiple samples, the means you get would cluster around the population mean
this makes the sample mean an unbiased estimator of the population mean: the average sample mean is the population mean

#

the difference is that one of them is feasible and the other one isnt
the sample mean being an unbiased estimator means the sample mean aims to be the same thing as the population mean

vale dockBOT
#

@willow arch Has your question been resolved?

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#
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sharp whale
#

np

vale dockBOT
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ivory bough
#

Maa chudao

vale dockBOT
ivory bough
#

Parhai kartey bhi ho Tum sab

north walrus
#

?

next vortex
#

uhh, do you have a question? kongouderp

vale dockBOT
#

@ivory bough Has your question been resolved?

lucid cedar
west coral
west coral
next vortex
#

hm

#

then I'll close this

#

.close

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humble flicker
#

<@&268886789983436800>

vale dockBOT
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split edge
#

is it possible to transform this ODE to a diophantine equation? for instance euler's method time discretiton

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#

@split edge Has your question been resolved?

vale dockBOT
#

@split edge Has your question been resolved?

wild linden
#

@split edge why specifically a diophantine equation?

#

because you have 4n/5 in the exponent, if you can you will be very restricted by what values of n are possible if you insist on integer solutions.

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#

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raven frigate
#

if i have a A=>B with perhaps steps in between and i know for certain A is true and from that following B is also true. in that case is it always true to also say B=>A?

pine prairie
#

if i have a A=>B with perhaps steps in between and i know for certain A is true and from that following B is also true. in that case is it always true to also say B=>A?

#

What does that mean

#

Also, if A is always true, then B => A is true regardless of what B is

raven frigate
pine prairie
#

Draw the truth table for B => A

#

It’s always true when A is true

raven frigate
# pine prairie Draw the truth table for B => A

okay so im right, right? so in that case could i have written <=> all along instead of => for the proof A=>B from the beginning or do i have to prove B=>A even tho we know its true given what we just discussed

pine prairie
#

If A => B and A is always true then A <=> B

#

But if A is always true and A => B then B is always true

raven frigate
pine prairie
#

A => B is just some operation on 2 statements

raven frigate
ebon glade
#

maybe a small rephrasing helps. if we know that A is always true, then any statement C=>A is true, no matter what C is. in particular those statements are kinda irrelevant

ruby sleet
#

as an example

raven frigate
ebon glade
#

you show that if A is true then B is true

#

and if B is true then A is true

#

if you want to show that A <=> B

#

you have to show both A => B and B => A

#

just doing one direction is not enough

raven frigate
ebon glade
#

no

wide gale
#

in general A=>B does not imply B=>A

#

so you need to show both

raven frigate
ebon glade
#

well sure but thats meaningless

#

why do we care whether B => A

pine prairie
wide gale
#

if both statements are true then yeah but theres no use for that really

ebon glade
#

if we know that both B and A are true

raven frigate
ebon glade
#

the color blue is blue implies that 2 is even

#

and 2 is even implies that the colour blue is blue

#

but who cares

pine prairie
#

It’s a valid statement

#

It’s just not often useful

wide gale
#

tautology strikes again

raven frigate
#

thanks!

turbid valve
#

!done, I assume

vale dockBOT
#

If you are done with this channel, please mark your problem as solved by typing .close

#

@raven frigate Has your question been resolved?

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buoyant sluice
#

I do not want an answer but some kind of hint on where to start with this question. This question is in the series, sequences, and binomial theorem part of my curriculum.

stark wedge
#

try to figure out the lengths of OB_1, OB_2, ...

red tulip
#

Whats the difference between each arc? Like is there a set difference in distance from the center

#

Oh nvm

buoyant sluice
#

okay! thank you!

#

.close

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harsh jolt
vale dockBOT
harsh jolt
#

How am I supposed to do this question

#

Never seen something like it

rough talon
#

which number

opal pendant
harsh jolt
#

Ok you will get $8k^7 -16 k^3$

opal pendant
#

oh wait sorry dont differentiate yet

rocky lotusBOT
#

playboi69

opal pendant
#

take k^4=a

harsh jolt
opal pendant
#

so now u have a quadratic in a

harsh jolt
#

Ye

safe fulcrum
#

RHS is a quadratic in k^4

harsh jolt
#

Ye

opal pendant
#

quadratic eqns have a minimum value

#

can u find that out

harsh jolt
#

-D/4a

opal pendant
#

yes

harsh jolt
#

It's -1/2 for this one I think

safe fulcrum
#

oh but that quadratic has complex roots

harsh jolt
#

I meant 1/2

opal pendant
#

a^2-4a+5
2a-4 = 0
a=2
4-8+5

#

how did u get 1/2

harsh jolt
#

Ye you are right

opal pendant
#

do u understand or are u just agreeing

harsh jolt
#

Nope i get ir

#

It

opal pendant
#

ok so minimum value is 1

#

can u see what we can tell now

harsh jolt
#

Ye

#

No not really

safe fulcrum
harsh jolt
#

Except drawing a rough graph of the quadratic

opal pendant
harsh jolt
#

So what am I supposed to do now

safe fulcrum
#

figure out if statement 2 is true or false

harsh jolt
#

Ye but how

#

I can't exactly draw a rough graph of it

#

To determine if it's true

safe fulcrum
#

let me remind you of function transformations then

#

start from sin(x)

#

then sin(3/2 * x) is a horizontal compression

#

with scale factor 3/2

harsh jolt
#

Ye but there is y inside cos

safe fulcrum
#

it's the same reasoning for cos

harsh jolt
#

No I meant the variable y

safe fulcrum
#

f(t) = cos(5t/3)

#

f(x) = cos(5x/3)

#

these are all the same function

harsh jolt
#

Ye true but what this all means sin has a different variable

#

Cos has a different variable

#

And they are multiplied together

#

Unless x = y

safe fulcrum
#

the question states that $x, y \in \mathbb R$

so $x, y$ are being treated as the domains of $\sin, \cos$

rocky lotusBOT
safe fulcrum
harsh jolt
#

Sin

#

Unless there is a restriction of domain

safe fulcrum
harsh jolt
#

In our case there is none

safe fulcrum
harsh jolt
#

Ye

safe fulcrum
#

yeah okay then statement 2 is true

harsh jolt
#

Ye

safe fulcrum
#

okay now, what's the absolute maximum of sin(3x/2) * cos(5y/3)?

#

based on multiplying them together as you said

harsh jolt
#

I have no idea

safe fulcrum
harsh jolt
#

Yea

safe fulcrum
#

well and you can assume that cos(5y/3) will be positive, since we want the maximum value

#

so multiplying gives sin(3x/2) cos(5y/3) <= cos(5y/3)

harsh jolt
#

Huh

safe fulcrum
#

multiply both sides by cos(5y/3)

harsh jolt
#

Alr

#

Ye how will this help us tho

safe fulcrum
safe fulcrum
harsh jolt
#

Ye

safe fulcrum
# harsh jolt Ye

it's like if I have p(x) whose range is 0 to 10
and if I have q(x) whose range is from 11 to 100

I can conclude that p(x) and q(x) never intersect

harsh jolt
#

Ye

safe fulcrum
#

you only need to check that 10 < 11 in that situation

harsh jolt
#

Ye just the range

safe fulcrum
#

what's the maximum of sin(3x/2) * cos(5y/3)?

harsh jolt
#

Cos 5y/3

safe fulcrum
harsh jolt
#

Wait one second

#

Cos 5y/3 <= 1
sin 3x/2 cos 5y/3 <= sin 3x/2

#

Is also true then

safe fulcrum
#

yeah if that's easier for you, I see now

harsh jolt
#

Ye like then what is the maximum value

#

Is it cos 5y/3 or sin 3x/2

safe fulcrum
#

so it's neither of those

harsh jolt
#

Ic

safe fulcrum
#

sin 3x/2 cos 5y/3 <= sin 3x/2 <= what number?

harsh jolt
#

No like that was the inequality

#

I got

#

Because both the statements should be true

safe fulcrum
#

well we previously established sin 3x/2 <= 1

#

so sin 3x/2 cos 5y/3 <= sin 3x/2 <= 1

harsh jolt
#

E

#

Ye

#

Ok so less than 1 in both cases then

#

Or equal to 1

safe fulcrum
#

okay!

#

yeah actually if sin(3x/2) = -1 and cos(5y/3) = -1

#

you also get - 1 * -1 = 1 as the maximum, so

harsh jolt
#

Yee

safe fulcrum
#

the negative numbers also worked out here

#

okay do you recall what the minimum of k^8 - 4k^4 + 5 was?

harsh jolt
#

Yea won't it cause problems

safe fulcrum
#

cool, so we have LHS <= 1
RHS >= 1

#

what must happen if LHS = RHS

harsh jolt
#

They both are equal to 1

safe fulcrum
safe fulcrum
#

okay so we're nearly done actually

#

it seems pretty obvious, but the important thing is that one value of x satisfies x^2 - 4x + 5 = 1

harsh jolt
#

-1

safe fulcrum
#

now at the start, we set k^4 = x

harsh jolt
#

I meant 2

safe fulcrum
#

so k^4 = 2, that has 2 solutions

#

k^4 = -1, well that has 0 real solutions, completely different story

safe fulcrum
harsh jolt
safe fulcrum
#

that's the same thing as square rooting both sides, and then square rooting again

#

but you can't square root a negative number in the reals

#

so like k^2 = -sqrt(2)

that has no solutions

#

we just have k^2 = sqrt(2)

#

2 solutions

harsh jolt
#

Ic

safe fulcrum
#

in general the (odd number)th root will give 1 sol

#

(even number)th root will give 2 sols

harsh jolt
#

Alr

safe fulcrum
#

yeah so answer is D

#

I found a million YouTube videos on this exact question lmao

harsh jolt
#

Oh damm I've never seen this type of question tho

harsh jolt
#

Thanks man

#

.close

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#
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vale dockBOT
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tranquil crane
#

Is there any chance that someone could explain this theorem and the subsequent proof? I’m confused on the definition of an orbital and how n-m is obtained

ebon glade
#

do you know what the representation of a permutation as a product of disjoint cycles is?

tranquil crane
#

Yes, I do

ebon glade
#

if I have a cycle (13562), can you write that as a product of 4 transpositions?

tranquil crane
#

(1 2)(1 6)(1 5)(1 3)

ebon glade
#

so for a permutation like (142)(35)(768) on n=8 with m=3 cycles, can you write it with 5 transpositions?

tranquil crane
#

(1 2)(1 4)(3 5)(7 8)(7 6)

#

Think I've gotten that right? Took me a while to type

ebon glade
#

well the point being that you write each individual cycle as a product of transpositions

#

for each cycle you need one less transposition than the lenght of the cycle

#

so if you have m cycles then you need n-m transpositions

#

which really is just the statement of the theorem

tranquil crane
#

Got it now, I couldn't see the pattern, nor the fact that orbitals is another word for cycles. Hours upon hours of studying and foggy brain! Thank you for your help!

ebon glade
#

orbits*

#

take a break

#

breaks are good

tranquil crane
#

Thank you again for your help!

#

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#
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#
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After 15 minutes, feel free to ping <@&286206848099549185>.
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harsh jolt
vale dockBOT
harsh jolt
#

I figured out the range for this one

#

$a^2 - 2a\in [-1,\infty)$

rocky lotusBOT
#

playboi69

harsh jolt
#

$cosec^2(\frac{\pi}{2}(a+x))\in [1,\infty)$

rocky lotusBOT
#

playboi69

odd jackal
#

uh

harsh jolt
#

Wait a second

odd jackal
#

it's a^2+2a

harsh jolt
#

Ye

#

Right

#

It's still -1

#

Tho the minimum value

odd jackal
#

yes

harsh jolt
#

So the only value where they can be 0 is when when the quad is -1

#

And cosec^2 is 1

odd jackal
#

yup

harsh jolt
#

So a = 1 but x should be

odd jackal
#

a=-1 you mean

harsh jolt
#

This aligns with option b but x is not a integer

#

Where did I go wrong

harsh jolt
#

No nvm -1

#

Ye so where did I go wrong here?

odd jackal
#

,rccw

rocky lotusBOT
odd jackal
#

okay so you want to solve $1= cosec^2(\frac{π}{2} + \frac{ πx}{2})$

rocky lotusBOT
odd jackal
#

can you silve this

harsh jolt
#

Ye

#

$sec^{2} (\frac{\pi x }{2})$

rocky lotusBOT
#

playboi69

harsh jolt
#

Ye got it

#

Thanks

#

Man

#

.close

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#
Channel closed

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vale dockBOT
#
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Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
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random hull
#

I have questions regarding this. Not only solving but i want to know the rules like i have some quries in mind

random hull
#

Helllo anyone here

tidal terrace
tidal terrace
random hull
# tidal terrace Do you know how integrals work ?

Yes i do. But the thing is i ended up with y^3/3 . a root 2.

But this is wrong. Just to be clear i'm first time encountering double integrals and triple. So yes i'm finding it hard

  1. Can i just swap the limits like inner limits to outer and outer to inner? and also swap dx, and dy? and then solve? Because there is no way to plot the region because how the function and its limits aare given.
#
  1. is the question wrong?
hollow shuttle
#

i think the question might be wrong

#

currently the answer depends on y

#

can you try replacing the upper bound of the inner integral with a and see if that gives you the right answer?

random hull
#

Can i just swap the limits like inner limits to outer and outer to inner? and also swap dx, and dy? and then solve? Because there is no way to plot the region because how the function and its limits aare given.???

Does this work? Or do i need to redefine the limits? like in each case.

hollow shuttle
#

in this case you should be able to swap the integrals yes

#

but there's something up with the question, you should probably ask whoever gave it to you to confirm if it's correct

random hull
hollow shuttle
#

the inner integral doesn't depend on x

#

so you can just move it out like you would with any other constant

#

and then move the other integral inside, because it doesn't depend on y

craggy rock
#

Bro

#

After we integrate the first one

#

We can move it out as a constant?

#

Cuz it has no relation or isn't a function of x

hollow shuttle
#

yep

random hull
hollow shuttle
#

yeah the question is almost definitely wrong

random hull
#

Wait so i can just swap the dx before and put dy behind and integrate the Y^2 respective to x?

craggy rock
#

No

#

How would you do that?

#

You can't swap dx and dy😭😭😭😭

random hull
# craggy rock How would you do that?

Just take 1 as a in multiply of Y^2 and get the integration "x" and the consider y^2 as constant 😭 DONT JUDGE ME I HAVE JUST STARTED LEARNING THIS..

craggy rock
#

I'm also dumb

#

😭😭

#

I'm so sorry i didn't mean anything like that

random hull
#

🙂

#

Change the order of integration

#

Yes thats very helpful

hollow shuttle
#

does this make sense?

craggy rock
#

Idk what that is either

craggy rock
hollow shuttle
#

every operation in this image is just moving constants in/out

craggy rock
#

Yup

#

That makes sense

random hull
craggy rock
#

This works

#

hollow shuttle
craggy rock
#

I'm getting that too

#

I'm confused

#

Is it possible the answer key is wrong?

#

To the guy who sent this

hollow shuttle
#

i'm pretty sure the issue is that the "y" in the upper limit of the inner integral should be replaced with something else

craggy rock
#

Instead of just y

#

Could've been a typo

craggy rock
random hull
random hull
craggy rock
#

Please😭

random hull
craggy rock
#

Whatever you're doing
Because I'm interested to see

random hull
craggy rock