#help-28
1 messages · Page 217 of 1
N? or like n -1?
Goëtia
what does this "N" represent? Is it the natural number such that for all n >= N we have s_n +1 /s_n - L < e?
Yes
well i let u with this idea first
how is it that you got (L - e)^{n-N}?
im telescopign rn but i only get L -e
try it
s_n/s_n-1 <= L-e
s_n-1/ s_n-2 <= L-e
....
s_N+1/s_N <= L-e
s_n <= (L-e)^(n-N) s_N
Wait bruh my internet just crashed but I had something like s_n+1 < e * s_n/s_N
multiply the inequalities i gave ya
Yeah I see I think i multiplied wrong stuff
shouldnt it be to the (n-N+1) power?
proof?
no
i think?
yes
then we presumibaly take everything to the 1/n power?
yes
do i also assume natural log preseves inequality?
u tell me
because we haventn relaly proved that
prove it
i think natural log is increasing function
but then that uses derivatives and stuff
wait this doesnt seem to use lim sup/lim inf tho
like here is what am getting
write
$(\frac{s_N}{c})^{\frac{1}{n}} (L - \epsilon) \leq (s_n)^{\frac{1}{n}} \leq (\frac{s_N}{c})^{\frac{1}{n}} (L + \epsilon)$ where c is a constant
LXDL
i simpliefed this: $(s_N)^{\frac{1}{n}}(L- \epsilon)^{1 - N / n}$
LXDL
yes
use that
wait sry when you say lim sup X, shouldnt it be $\sup {s_{k+1}/s_k : k \geq N }$
LXDL
or am i missing smthing ehre
wait wha.. so what is X then?
X = s_n ^(1/n)
ah okay hmm, but here how did we reach this conclusion? it seems we just got rid of the s_N/c term
or like the s_N term in general
what is u talkin about?
im confused on how we get lim sup s_n^(1/n) < L + e
$\frac{\ln(s_N)}{n} \rightarrow 0$
Goëtia
yes
thus $(s_N)^{1/n} \rightarrow 1$
Goëtia
LXDL
and we have $n \geq N$
LXDL
we need to show that the sup of that is less than the sup of somethign else tho
im confsued as well
idk bro im trying but im just getting confused
im not sure what we are trying to do here
like did we just show that lim sup = L
or
and now we are done?
wait
oh wait
is that what we just did
we show that lim sup = L
and by same reasonign lim inf = L
so we are done?
but this part is correct right
not sure why we need to use this tho...
like im still trying to think how we just got L-e < s_n ^ (1/n)
bcz u asked how did the s_N/c disappeared
u asked the obvious
but dont we need to show using epsilon delta?
tf?
because i dont think i can just say "since limit of any x> 0 x^{1/n} -> 1"
so you are saying we have $L - \epsilon \leq\lim s_n^{1/n} \leq L + \epsilon$?
LXDL
yeah im confused from the second to the third step
if lim inf X = lim sup X = L => lim X = L?
yea i get tat
but not sure how lim inf s_n ^(1/n) >= L - e
$inf (s_n)^{1/n} \geq (s_N)^{1/n} (L- \varepsilon)^{1-N/n}$
yes i agree with that
you take limit both sides as n ->infty
Goëtia
can continue?
u continue lol i aint doing ur hmwk
no i mean L - e cant jsut result from that right
u figure it, u got the tools now
ok thanks
also this looks similar to gpt background but idk
if gpt can do that, then go ask it
ok sry. i tried but gpt doesnt really explain
good luck
i use gpt, to directly give me the rendered latex , without being correct in writing the latex code
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Number 2
,rccw
i’m not sure what i’m doing
it asks to indicate the portion of the unit circle that satisfies the inequality, sketch a rough graph, then write in interval notation
!show
Show your work, and if possible, explain where you are stuck.
I don’t know where to start
other than me knowing where cos is -rt2/2
would the interval notation be like
<@&286206848099549185>
looks correct
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one thing, make the ] a ) at 2pi
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Hello,
I was wondering if someone could tell me the steps to answering this problem? I am having a bit of trouble comprehending how to solve it...
Any help is most appreciated
Try construct a line than connects the 2 points where the lines touch the circumfurence to create a triangle
Then find the arc
Then the angle
Then the other angle and finally x
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I've been banging my head trying to prove this for a couple of hours now and Im pretty sure its something silly that Im missing
$(A - B) \cup (B - A) = (A \cup B) - (A \cap B)$
Creeperarcade 2.0
I applied the set difference identity and simplified it to the following
$(A - B) \cup (B - A) => (A \cap B^c) \cup (B \cap A^c)$
Creeperarcade 2.0
and I cant use a distributive law because they dont both have the same letter in them
I'm not allowed to use that
why not
ok
I got a zero on my last assignment for using set algebra when we were practicing double inclusion
ik stupid but thats why its hurting my head
if you want to do it a similar way then
why not write "- (A cap B)" as "cap (A cap B)^c"
so start from the RHS and get to the LHS
$- (A \cap B) = \cap (A \cap B)^c$
Creeperarcade 2.0
I mean coupled with the rest
$(A \cup B) - (A \cap B) = (A \cup B) \cap (A \cap B)^c$
rafilou is not not born in 2003
try to arrive at the LHS yes
it took me like 5 minutes to process that sentence
let me try that rq
thats actually such a smart way to reverse engineer the question
thank you
so much
I got it
I'm got so zoned in on the LHS that I forgot about the RHS
that was fast
I mean
it doesnt matter, u can still apply it
after getting $(A \cup B) - (A \cap B) = (A \cup B) \cap (A^c \cup B^c)$
rafilou is not not born in 2003
how so?
i thought they both had to be the exact same
either $A^c$ or $A$
Creeperarcade 2.0
hold on
so that is just the application of the distributive law for union?
i thought they had to match?
basically ye
so how is that law applicable
let X = A intersect B^c
do X U (B intersect A^c)
X U B intersect X U A^c
expand X
$(X \cup B) \cup (X \cup A^c)$
Creeperarcade 2.0
oh I see
wait
omfg
I didnt entirely understand what you did I get it now
it took the variable analogy
I thought you mean reversing the distributive law
thats what I was looking at
so going from the RHS of the law and turning it into the LHS
no i just answered ur first question, bout why u couldnt use the law
yea i understand now
thank you for explaining that concept
I didnt know that was a proper way of applying that law
but my idea to do the proof, is just endup with a similar expression for both the RHS & LHS
if they are equal to a similar expression both of them then they must be equal
a=c && b=c => a=b
yea i understand that
the way we are required to do it
is start with one side and turn it into the other
discrete math is such a new concept to me
this was super helpful I can finally get my assignment done
i knew it was something tiny
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how would I write this graph in four ways sin, -sin, cos, and -cos?
Lets start with sin
is there any extra info given about the point?
no
Do you know about $y = a\sin(b(x - h)) + k$
King Leo
What more info is needed?
yea
So whats the amplitude of this function
that its a minimum?
Oh i see
2?
So whats a
2
if its not a minimum, the amplitude is greater than 2
Fair point
But i think its safe to assume thats a minimum point
$y = 2\sin(b(x - h)) + k$
King Leo
@spring bay do you know what b does
is that like the dilation?
no, how would I find that
Close, its like a horizontal stretch. You can find it using pb = 2pi, where p is the period of the graph
wait how did u get the period?
You can look at the graph
It requires a little bit of extra thinking
Do you need help?
yea
is it because one full revolution on a unit circle is 2pi so for sin one full revolution it’s also 2pi?
Hint: the horizontal distance between an extreme (minimum or maximum) and the closest midline is 1/4 of the period
In other words:
Each line segment that i drew on the x-axis spans about 1/4 of the period
ohh alr
wait can we also just assume that the graph is in the standard shape of sin without compression or stretching in the x-direction?
No you cant. Thats the point of finding a, b, h, and k
But for the purposes of the drawing, it works on any sin or cos function
#help-28 message
That's why one revolution of the default y = sin(x) has a period of 2pi
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why is this wrong?
@runic heath Has your question been resolved?
(3,0) is not on the line
(4,1) is
Use that instead
ohhh the only line i can use is the adj?
like the line that touches the blue area?
can i use (3,2) then?
@runic heath Has your question been resolved?
<@&268886789983436800> anyone knows?
You can decompose this area into two parts
A square and a triangle
How would you do that?
Yes that's on the line
@runic heath Has your question been resolved?
bottom part square and top triangle? but what does that give me
Oh wait it's integration lol
You know how to find the equation of a straight line from 2 points on it?
yes
i see lemme try with 1,4 and 3,2
You could take any two from (1,4), (2,3), (3, 2), (4,1)
4,1 would work even if it's outside of the area?
Yes because we just want the line for now
thank you i solved it the area is 6
is this one also about just finding two points of the red line?
Yes
But you must be careful
The line has breaks
You should be careful to only select points which are on the same slope
so i only pay attention to x=0 and x=1?
the slope is the entire red line?
The function is piecewise
how so
ohh right cuz it's a sharp turn
If you find two points between x=1 and x=6
And find the line connecting them
and then substitute x=0
you wouldn't get the right answer
^^
ohh
yes
So you must be careful
The first part, you can go as normal
What is the equation of the line for x=0 to x=1?
first part two points can be
(0,-3) and (1,-3)
second part two points can be hmm
it all has to be either below or above the x axis? not mixed?
or not mixed with the straight line afterwards
like what if i pick (2,-2) and (5,1)
for the second one
It can be mixed
i see so this should do
thank you ill calculate and come back with answers haha
first equation is f(x)=-3
integrated is -3x
area=-3
how can the area be negative
It's under the x axis so it's negative
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I got the right answer butttttt
Im noticing ive developed a bad habit 😅
I dont really read the questions, I kinda just guess what I need to do, like I see the word 'distance' and I just think oh put it inside sqrt(a^2 + b^2) and see what happens'
And yeah I got lucky this time
But I need to stop this habit, because even though I 'know' how to do it, I still dont really know what the question is asking
Like what does it mean by 'as a function of t'?
And 'Your answer should only contain only one sine or cosine and one t', this is supposed to give me a hint to suggest a certain way of how to approach the question right? What is that hint?
it means that your answer has to have t in it, as opposed to just being a number.
which would be a natural consequence of doing it the correct way anyway
no, it's just a goal for how much you should simplify your answer -- so that you cannot just pop that shit into the distance formula, decide not to simplify it at all, and call it a day
Ahh I see that makes sense
Ok well I understand the question a lot more now haha
Thank you!!
Also welcome back!! Where have you been you were the most active person on the server then you just dissappeared for like 2 years 😝
1
Dont pick up the phone, you know hes only calling cause hes drunk and alone
Ok well... good to see you
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Could anyone help me solve this? I don’t understand what to do
Think of some number a such that $6a^2$ or $60a^2$ is the number inside the square root
CST (please ping when replying)
Sorry I don’t understand do u think u could explain a little more? 😢
10^2 x 6
Ohh
Linearization L(x) = f(a) + f'(a)(x - a) (oh... not calculus yet)
And then after that how can I use the decimals provided?
I don't think shes doing that xd
you can use that fact sqrt(ab) = sqrt(a) * sqrt(b) !
if you notice that 600 = 6 x 100
u can split it up
yea!
Then would I have to divide for questions like d)?
mhm
Can it be further simplified?
yes
the kinda theme of all the questions is like
how can u change it to k sqrt(6) or k sqrt(60)
Ohhh I see now
np!!
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What you have to do with this?
nvm i got it
make venn diagram with that info
then find probability of spanish which i can do
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Could someone help me solve for c and d
Pretty sure PBS and QCS are similar but I don't know how to prove them
BSC and QSP are similar
thats it
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i need help
determine the slope of the tangent line at point (-2,2) on the curve f(x)=2x^2+3x
i’m using limits
just started calc
and that’s all my teacher taught
grade 12
is this wrong then gang 💔
icl if she seen me use this i don’t think she’d pass my ass
it’s an assignment that was due like an hour ago i just woke up 😭
oh word
bettt
thanks bro
yeah my teachers super good she like gives us the super long and boring way first
for us to understand it
then she’s gonna teach us all the shortcuts
i’m hyped
cyaa
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How do I get the equation of a parabola given two points (x1, y1), (x2, y2), and the y-coordinate of the vertex k?
This is what I've already tried but solving for h looks like a cubic (I don't know how to get solutions for cubics with variable coefficients)
Should I continue from here or try a different method?
Oops
I made a mistake
I accidentally wrote y1-h instead of y1-k somewhere
imma see if i can solve it now
I think i got it
nvm sry abt that
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5x^2+3x-5 identify the Like terms
!status
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
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how do i find out quartile 1, quartile 3, ect? im confused af im dumb 😭
do you know how to find the mean?
Okay try finding that for this data set
Not sure if I follow but kinda?
ohh okay
wait a sec
wait @random glacier I'm sorry I don't know the english terms but what I was thinking of is the median
okay well what it is
the mean and median r different wait a sec
yeah you might as well say the mean though to make sure you understand how you get it
you mean the, mean right if so yeah!
but what about the median
72 i think 😭
what does your ordered data set look like
wdym?
69, 70, 70, 71, 72, 74, 76, 78
okay and the median is the central element right?
you have 8 elements
no you add the center two
The median is the central element, since we don't have a middle one we take the average of the closest two
not rlly 😭
okay so like,
the median is the center of our data set
yes
okay that makes sense
idk how to figure it out 😭
Okay so like
let's take this
the median is the center of our data set
the quartile 1 is the center of the lefthand side of our data set basically
so what's the median of 69,70,70,71?
70
yeah
so then what's quartile 3
These are the quartiles
69, 70,(70) 70, 71,(71.5), 72, 74, 76, 78
75? 😭
yeah!
so then which one of these is right
Q2=71.5
I said this badly but like
basically the quartile 2 divides the data set into 2 sub-sets(what's left and right to it)
and the quartile 1 is just the median of the left-hand side while the quartile 3 is the median of the right-hand side
yes!
because our 1st bit is the minimum of the set, 69
the left side of the rectangle is Q1, so 70
the middle bit of the rectangle is Q2, so 71.5
the right side of the rectangle is Q3, so 75
the final bit is the maximum of our set so 78
by the way you NEVER include the Q2 in the two sides, so if we for example added 71.5 then our minimum,Q1,Q2,Q3 and maximum would be the same
tyty
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Hello
Is everything here correct?
Btw Idk why the first one is 3 marks i feel like im missing something
If the first one is wrong how is this
So what negative did i multiply
Ohhh ok
Is the second image wrong as well
👍
Hows rhis
How is this
What sign do i use than
So is questuon 4 correct?
You can always check on desmos.com
The one you wrote on the test no
Lol
I thought the same
Sup
Ok so did i write the right thing?
When you have a quadratic like that its good to put it on a grapsh
Yea
Not on the test tho
You would lose points if u divided like that
Oh ok
And question 5
A and b
Are these correct?
The completign the squayre
@keen bloom
Uh sorry
Bruh
You were supposed to find the turning point
Factor out the 3
Then complete the square
yh
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Guys, it is urgent
I need to know how to convert mg/L/h into ml/h
According to my situation, I have 0.735
And I am lost since I can't get any information that helps me going further welppp
those do not appear to be compatible units
Dang
I am helping my friends with a scientific project and they asked me how to do it
Is there any way for me to make them compatible? With a litrage or smth
(if I end up with mg/H)
Ah yeah I guess I will just need Co2's density?
the first one appears to be density per hour(?) and the second is volume per hour(?)
If you need more context, It is a plant's Co2 absorption
They found out the plant could absorb 0.735mg/L/H
There is no specific questions
They just wanna convert it to compare it to other plants
Which have values surely said in ml/h
ah I see now
I think measuring co2 absorption in density/hour is completely wrong
it should be expressed in ml/h or g/h
Oh
Internet told me it was possible
could you send me the source you used?
Let me ask 'hem
Bruh I just said it was me
Let's say I just asked chat got and got this
Oh wait
Tf
I am so lost
I'm tired af
'kay so
I am theorising
If we divide what we got by the liter of the box
Do we get rid of the liter thing ? ( I do not know all the steps they have done so far)
!nogpt
Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).
Ah yeah but it wasn't to answer to my own question
I answered people where the mistake could be
I am better in maths than I am in actual chemistry (I haven't worked on this during my chemistry classes) and I can't find where to get infos
Usually, he redirects me on websites where I can verify the infos, but here I can't
That's why I am asking you
But I'll be careful with showing my mistakes (when I helped myself with Chat gpt) here
you need to just form your question properly
Yeah but in that case
I am definitely lost
I don't even know what to ask properly so chat gpt won't be a useful tool
no one knows what you're asking man. go ask your friends for more information
Nevermind they gave up
It's late so we all are very tired
Sorry for bothering you all
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Am i able to do problem 39 without using a triple angle identity?
yes
how would i set it up?
i know cos theta is x/r
but how would i do it with the
cos(3theta)
ah
just trace r = cos(3theta) for theta = 0 to pi/6 first, then pi/6 to pi/3
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thx
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how do i solve a² + b² - ab = 1 in Z
and then
ehh wait
one set of solutions is 1, 1
for sure
-1, -1 as well
given that this is the graph
therefore -1, 0 is also a solution
1, 0 as well
the og question was : for all a, b in Z, show that N(a+bj) = 1 if and only if the pair (a,b) is (+ or - 1, 0), (0, + or - 1), + or -(1, 1)
thanks for hiding it
we have solutions: {a,b} = {1, 1}, {1, 0}, {-1, -1}, {-1, 0}, {0, -1}, {0, 1}
but that's only from graph
there are many solutions as you can see on the graph
ohhhh
then N(a+bi) = ab + 1
therefore to satisfy N(a+bi) = 1
ab + 1 = 1
ab = 0
||
substract ab on both sides, you get (a-b)^2 = 1 - ab, so you need 1-ab>=0, i.e. ab<=1 to have a solution
now if you add 3ab instead, you get (a+b)^2 = 1+3ab, i.e. 1+3ab >= 0, i.e. 3ab>=-1 is required
that limits your options pretty quickly
||
My recommendation was to distinguish cases ab <= 0 and ab > 0
in the latter case it helps rewriting a^2 + b^2 - ab = (a-b)^2 + ab
so since we know that we need ab <= 1 to have a solution, if ab>0, we need to have a = 1 and b = 1 or they're both -1 or they're both 0 or one of them is 0
now if ab<=0
we cannot use the first condition given by aplatypus
if we use the second one
3ab>=-1, with ab<=0, ...
ab has to be 0
i dont know
can we use the previous question? The one that we just solved with U(A)?
got a link to it ?
this
well do you have another way of finding the units of A without using that norm argument?
no, in fact it's kinda the opposite
we rather find all units of A
by solving N(z) = 1
yeah the norm is here to help you
instead of working with A directly which might be pretty ugly, you just work in Z
yeah -1 <= 3ab <= 3, combining the two inequalities
so indeed as you said a=0 or b=0 works
if both aren't 0 you have almost no leeway at all
the first condition gave more solutions, but a or b dont need to be 1 as long as the other is 0
so is there a way to find all of the solutions?
@kindred grove
yes, if you push the reasoning with these inequalities just a little further
what a,b actually satisfy these inequalities if both are non-zero ?
@unborn acorn
1 and -1 but for the first condition, if we assume ab>0 and we know ab <= 1 if we want a solution, if we take 0, a can be anything
yes i know
I'm deliberately excluding the case where either is zero, we already covered that
ok but we also need to study that case?
which one ?
- either one of a,b is zero, then (a,b) satisfies the inequalities
- or a and b are both not zero, and this forces (a,b) to be ???? to satisfy the inequalities
my question is what do you put in the ????
(1,1) or (-1, -1)
yes indeed
so with these two inequalities we managed to restrict a lot which points (a,b) we need to look at
now you can plug in these cases in the original equality
and see which (a, b) are actually solutions to the equality
ok, so normally i just need to plug in the first case where one is 0 and then it should force the other one to be 1 or -1?
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@unborn acorn the ellipse & the inequalities, looks cute
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how can you tell if a fujnctions is decreasing by find the dervaivtre
if dy/dx < 0 then it's decreasing
dude what?
u wanna explain what ur question is?
you can find the critical points and test
i see
ok im so confused but whatever
depends where your serie starts
where dy/dx = 0
oh
so 0
and then is it something like where i pick a numvber greater tahn 0 and less than 0
and if the side is postive i put+
desmos gives me sqrt(e)
but yeah with integral test you only have to show that the function is eventually decreasing
can you show the original serie this is about
what's the question rn
ive done this calc1 but its only for ones not in fractions
how wouyld i do this
would i rewrite it?
or is there another way
without rewriting it
to find the critical point
these are he ones i see
bnefore
@tulip oriole
Wdym without rewriting it
You need to differentiate it though
to find the cricitcal point
And to see where its decreasing/increasing
once you factor x out it's just 3-6ln(x) = 0
@wicked zodiac Has your question been resolved?
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can someone explain how this works to me
$g(f(x))=g(y)$, where $y=f(x)$
;(
So essentially, f(x) is the input for g(x)
In math notation this would be $x\to f(x)$ roughly
;(
im still a little confused
\mapsto
like how does g of f become (0,3)
I didn't choose that since notational stuff, I chose the more lenient notation
Because of the original x-input for f(x) which would be f(0)
for example, if f maps 0 to 5 and g maps 5 to 3, then g o f maps 0 to 3
f(0)=5, so g(5)=3 is what we want
g takes the output of f as an input
OH OKAY
WAIT THAT MAKES SO MUCH MORE SENSE
I WAS DOING IT BACKWARDS 😭
thank you!!!
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How do I show that (-inf,2) isn't bounded below ?
I understand that I let a∈ℝ and construct an x∈(-inf,2) such that x>a so the set has no lower bound but how do I construct it
If I just say "oh x>a" then I can argue that for any set and say anything has no bounds
you cant do this by contradiction? like suppose (-inf, 2) has a lower bound B, prove B-1 is in (-inf, 2), that's a contradiction
I can but I'd rather understand the way the course mentions
rather than just go around the issue and ignore it
Do you mean such that x<a?
Yea mb
Np
Can you show me an example of the way you are trying to use
Like an example from the course or something like that
I don't at all understanding the courses example but its showing that (2,inf) has no upper bound:
Plan for the proof:
Show there exists no a∈ℝ:x<=a for all x in the set
Given a∈ℝ, pick x'∈(2,inf), x>a
e.g x'=max{a+1,3}
Proof:
Let a∈ℝ, write x'=max{a+1,3}
Then x'>3, so x>a+1>a
So a is not an upper bound
None of that makes sense to me I'm ngl, unless you assume a isn't in the set but thats just assuming there's no number bigger than infinity then by defining x'=max{a+1,3} to be 3
Idfk
I'm gonna go look at the lecture slides to see if that is how they did it bc that's what I have in my notes and it makes 0 sense
If the way you are talking about is just taking any a in (-∞,2) and showing that there exists x in (-∞,2) such that x<a then just take x=a-1 for example
For any in a in (-∞,2), a-1<a
So that a is not a lower bound
Are you sure this proof is exactly a proof written in your course ?
From the lecture slides
The bit at the bottom in black is the "proof"
Hes assumed all a∈ℝ that aren't in the set are smaller than 2, which defeats the point of a proof
Cuz if you can just assume a is smaller than infinity, just say "no number is bigger than infinity" so there's no upper bound
Do you understand this at all @simple ridge
It just makes 0 sense to me
Tbh I think this is making the proof longer than needed
Not to say that it is incorrect
So let me tell you what is going on
So the claim is that given any a in R , a isn't be an upper bound of (-2,∞)
So first of all choose any a in R
Then either a=< 2 or a>2
Right
If a=< 2 then you can take x=3>a(which is in (2,∞)) so that x>a and hence a is not an upper bound of (2,∞)
You are left with the case of a>2
If a>2
Then a+1>3 so that a+1 is in (2,∞) and a+1>a so that a is not an upper bound of (2,∞)
This proves the claim
So the purpose of x=max{3,a+1} is :
- to make sure that x is in (2,∞).
- to make sure that x>a
Hmm I see
I still don't quite get the reasoning I'm sorry
Ik I'm being a dumbass rn
No you are not
Tell me what is still bothering you
let x=max{a+1,3},
a>2 so a+1<3, so x>a+1>a
ahhh and x is in the set so an x in the set will always be bigger than a∈ℝ?
And for the case a<2, x=3 which is in the set
This is not quite right
a>2 doesn't mean that a+1<3
Oops I meant a+1>3
Ohh in this case what you said is correct
Nice thank you
Everything you just said is correct and exactly describes the proof that you sent
The question on my assignment is showing (-inf,5) has no lower bound but same argument with x=min{a-1,some number smaller than 5}
🙏
Exactly
Great job 
Np but I didn't do anything, you did the work
What do you think
for min{a+1, something}
I would like to hear your opinion
I think if x=min{a-1,5}
If a>=5 then for example 3 is in the set and smaller so a isn't a lower bound
If a<5, then a-1<4 so if x=min{a-1,4}, x<a-1<a and x is in the set so x<a
Right?
Wait x<a-1 is wrong? x=a-1 moreover
a-1<a
So x<a
?
I need help. It 24 I need a positive and negative answer. The numbers are 7,-7,-5,-2
Did you mean to write x=min{a-1,4} in the first line ?
Yh mb
Np I was just checking
Its x=a-1<a right? Not x<a-1<a
Yes
But I have a comment here
Ofc
Just to make your proof look better
Ah wait no
mb
You don't know for sure that x<a-1
For example take x=4.5 then x<a but x>a-1
Yea so if a<5, x=min{a-1,4}=a-1<a
so x<a
?
And that means there's no lower bound bc if x=min{a-1,some number smaller than 4}=a-1, x must be in the set
right?
It's all good its 4am and my flatmate won't stfu talking to me in the library
Its 1 am for me xD
So I can't think either
Ohh then your condition is worse than me
is there an issue with my maths?
Ok so x=<a-1 is guaranteed because x=min{a-1,4} so if a<5 that means a-1<4 which means that x=a-1 . If a>=5 then a-1>=4 so that x=4
other than this you have no real issue. Just a slight fix , if x<5 then x=a-1<a and x is in (-∞,5) so that (-∞,5) is not bounded below (you shouldn't repeat that x<a, especially in the way you did it)
That's just for a better structure of the proof
But the ideas you wrote are correct and complete
Forgive me if I caused a bit of confusion above
All of the ideas are correct but I suggest that you define x hat in case 2 instead of defining it at the beginning since you didnt use it in case 1
Also in case 2, x hat=min{a-1,1}=a-1 and a-1<a do x hat < a
You shouldn't mention that x hat in E when you say x hat=a-1 and a-1<a
Only after you say x hat<a that you mention x hat is in E
You can even make the structure better if you want but that is not a big deal rn
What matters the most is that your proof contains all of the necessary points
Just fix the structure of the proof slightly as I told you and then you will be done
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Again I have a query
How do I show that {n∈ℕ:(1+1/n⁴)} has no maximum element?
Uhhh