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3:48 AM
Simplify $$d/dx\int^{x^3}_{t^2}\frac{dt}{\sqrt{x^2+t^4}}$$
The answer given is
${3x^2}/{\sqrt{x^2+x^{12}}}$$-\int^{x^2}_{t^2}{\frac{xdx}{(x^2+t^4)^{3/2}}}$
I am not getting the it by applyig Leibnitz rule as I am not using it properly
Please someone help
@Mann
 
4:14 AM
@AjayMishra lets continue here
 
The general formula is $$ \cfrac{d}{dx} \int_{\phi(x)}^{\psi (x) } f(x,t) dt = \cfrac{d \psi(x)}{dx} f(x,\psi(x)) - \cfrac{d \phi(x)}{dx} f(x,\phi(x)) + \int^{\psi(x)}_{\phi(x)} \cfrac{\partial f(x,t)}{\partial x} dt $$
@Jasmine there must be $x^3$ as the upper bound of the integral in your answer.
You got that?
 
4:36 AM
@AjayMishra I didnt knew this
Thank you !
 
Can you do this now?
 
@AjayMishra yes !
 
There should $dt$ though in your answer. I bet the author must be Indian.
 
@AjayMishra no wait
@AjayMishra @AdvilSell

  Basic Mathematics

This room is meant for all basic mathematical discussion, incl...
Cone to the above room
 
What you specifically wanna point out there?
 
4:50 AM
@AjayMishra I was already into discussion on this
 
$t$ is not constant, it is just independent of $x$, $ \cfrac{\partial y}{ \partial x} = 0$ if $y \ne f(x) $
 
@AjayMishra I get this you are correct I guuess its a JEE problem I guess there is misprint only
 
5:18 AM
@Mann hi :-)
When is real analysis taught ?
Is it in 1st Semester ?
Which book is good for a novice or a beginner ?
 
 
1 hour later…
6:39 AM
Real analysis is taught in 6th semester
Or 5th
And only to M & C people
You can use book named real analysis by Stephen Abbot 2e
That's the best undergraduate book I think
 
@Mann okay , thanks !
What topics are taught in 1st Semester ?
@Mann
 
 
1 hour later…
7:55 AM
Pretty easy one in my institute at least
I'd recommend buy one of those "engineering mathematics" book, perhaps by Erwin Kreyszig
It will have all the content you need
It's like a compilation of most important topics, specifically covered in 1st or 2nd year
 
8:25 AM
@AdvilSell
If you wanna study rigourous mathematics. Then I'd suggest do not follow engineering mathematics book. Instead follow some theoretical one, but it will take longer time.
You can still use the real analysis book. It's undergraduate and doesn't require prerequisite. But it will be slightly hard to read at this level. But if you get used to reading such statements at this point of time. You will be able to do really well
Even the basic chapters would do, as long as you practice 'reading' mathematics
 
 
3 hours later…
11:39 AM
Fun question :
Suppose you have the numbers k, k+1 , k + 2 , ... , k+n-1
And let's make a number X by adding all these numbers in all possible combination (with repetition)
Only addition operator is allowed (no subtract)
What are the numbers that can't be covered by X
 
one of them must be k-1
 
k > 0 and (n-1>0)
 
(0,k)
 
And everything is Integers*
Or just, all non negative integers
 
okay. No problem. Well, how good is guess (- infinity,2k) ?
 
11:45 AM
@AjayMishra yes this is true. All numbers less than k will not be covered
It will not always hold
But it's going closer yes
 
Numbers less than 2k are not also covered. you can't add k + 0
 
If (n-1) > k it will
Anyway I won't spoil it now for a while. I will come back in a bit
 
 
12 hours later…
11:57 PM
Solutions. Define alpha = greatest integer [k/(n-1)]
Run a for loop from i = 2 to alpha
Fill all the numbers between (i-1) * (k+n-1) to i * k
All these numbers are not possible to cover
 

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