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Yuvraj
6:30 AM
@robjohn but above is the fractional of x as well
$\lim\limits_{{x}\to0}\frac{x}{\tan(x)}$
so sorry sir for replying late actually I am in the rural area so network connectivity is not good here
robjohn
6:47 AM
I am not sure what you mean. $\frac{x}{\tan(x)}=\frac{\cos(x)}{\frac{\sin(x)}x}$
Yuvraj
$\lim\limits_{{x}\to0}\frac{{x}}{\tan(x)}$
sir x in numerator and denominator is the fractional part of x replace x by fractional part of x sir
robjohn
Well, then write that. Do you mean $\{x\}=x-\lfloor x\rfloor$, or the odd function $\mathrm{sign}(x)\{|x|\}$?
Yuvraj
the first one
$\{x\}=x-\lfloor x\rfloor$
robjohn
then the limit is not $1$
Yuvraj
why sir?
robjohn
6:56 AM
from the right it is $1$. From the left it is $\cot(1)$
$\lim\limits_{x\to0}\frac{\{x\}}{\tan(\{x\})}$ does not exist.
Yuvraj
can we prove it anyaltically
robjohn
from the left $\lim\limits_{x\to0^-}\{x\}=-1$
Yuvraj
how?
robjohn
That was the definition of $\{x\}=x-\lfloor x\rfloor$ you chose.
Yuvraj
how can this be possible where the exact value of the function can't be 1 or -1 how can it's limit equal to that
robjohn
7:02 AM
$\lfloor-0.0001\rfloor=-1$ so $\{-0.0001\}=-0.0001-\lfloor-0.0001\rfloor=0.9999$
Yuvraj
yes
but that is an exact value somewhere on the line?
robjohn
what do you mean? Those are exact values.
Yuvraj
sorry sir nothing I got it one more similar question sir if x tends to infinity then?h
robjohn
$\{-0.0000001\}=0.9999999$
$\lim\limits_{x\to\infty}\{x\}$ does not exist.
Yuvraj
by the same logic?
robjohn
7:08 AM
as $x\to\infty$, $\{x\}$ fluctuates between $0$ and $1$
Yuvraj
yes
robjohn
like a sawtooth wave
/|/|/|
Yuvraj
yes sir
and tanx will also be near zero
@robjohn i was solving one of the questions where he says $\lim\limits_{x\to\infnty}\lfloor x\rfloor$
same limit x tends to infinity
is it correct ot say this?
robjohn
what does he say about $\lim\limits_{x\to\infty}\lfloor x\rfloor$?
Yuvraj
yes
robjohn
7:18 AM
???
$\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$
what does he say??
Yuvraj
he says it limits be same as of the $\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$
i mean$\lim\limits_{x\to\infty} x=\infty$
robjohn
$\lim\limits_{x\to\infty}\{x\}$ does not exist.
Yuvraj
it gif
robjohn
are you not seeing the MathJax rendered still?
Yuvraj
i can see
robjohn
7:22 AM
Okay, it seemed as if you were trying to write
$\{x\}$
and were writing
${x}$
instead
$\lim\limits_{x\to\infty}x=\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$
Yuvraj
i am lost i feel
13 secs ago
, by
robjohn
$\lim\limits_{x\to\infty}x=\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$
i mean this only
robjohn
$\lim\limits_{x\to\infty}\{x\}$ does not exist
@Yuvraj okay
Yuvraj
it is a new question
40 secs ago
, by
Yuvraj
13 secs ago
, by
robjohn
$\lim\limits_{x\to\infty}x=\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$
robjohn
Do you not understand that which you have quoted twice?
Yuvraj
not fully
robjohn
7:28 AM
they both grow unboundedly as $x$ does.
$\lim\limits_{x\to\infty}x=\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$ but $\lim\limits_{x\to\infty}\left(x-\lfloor x\rfloor\right)$ does not exist
Yuvraj
yes sir so it is correct?
robjohn
if $x\ge100000$, then $\lfloor x\rfloor\ge100000$, etc. so if you mean $\lim\limits_{x\to\infty}\lfloor x\rfloor=\infty$, then, yes, that is correct.
Yuvraj
ok, sir, I have one more fundamental question if I write $\lfloor {sinx+cosx}\rfloor$
how would i draw
it sir always struggle whenever I try to fraw gif graph
@robjohn
robjohn
It might be more explanatory to see this...
Yuvraj
yes
thanks for your time sir
robjohn
7:57 AM
Here is a labeled version
5 hours later…
Yuvraj
12:29 PM
@robjohn sir if you are free please kindly look at this figure I need to find the maximum and minimum area of quadrilateral
Since the points on the sides of the square
robjohn
1:17 PM
maximum is $1$, minimum is $0$.
the area is $\frac12(1+d-b+ab+bc-cd-ad)$
$a=b=c=0$ and $d=1$ gives $1$
$a=c=d=1$ and $b=0$ gives $0$
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