From INTEGRATION SIKHO - l l

Hi T IIT IIANS !!!

58 Answers

4
UTTARA ·

1 ) integ [ e x2 ] = ??????????

Clue : Is it Integrable at all ??????????? : )

1
RAY ·

errr it doesnt seem to be integatable by byparts atleast...:)

1
RAY ·

how do u knw if a functon is integratable or not????

4
UTTARA ·

Only differentiable functions can be integrated

4
UTTARA ·

f'(x) = 2x ex2

LHL ≠RHL

Hence , the function is not differentiable & thus not integrable

4
UTTARA ·

2 ) Let f(x) is a quadratic function such that f(0) = 1 & ∫ f(x) dx / (x2 (x+1)3 )

is a rational function , find the value of f'(0).

11
Mani Pal Singh ·

good initiative [1]

1
rahul nair ·

Q2..let f(x)=ax2+bx+c......
f(0)=1,so c=1.
\int bx/(x^{2})(1+x)^{3} is not rational.......
so b=0..
so f(x)=ax2+1,
f'(x)=0

4
UTTARA ·

Thanks Rahul
Good solution !!!!!!!!!

1
RAY ·

RHL ≠LHL at which point uttara???

1
rahul nair ·

LHL≠RHL at x=0....

4
UTTARA ·

Yes Rohit
Rahul is right
LHL ≠RHL at x= 0

since at x=0 LHL <0 & RHL > 0

1
RAY ·

but we culd integrate it from 1 to n

4
UTTARA ·

Ya Rohit That's possible

But in my Qs an indefinite integral is asked for & not a definite one right? :)

4
UTTARA ·

I had to start this new thread on INTEGRATION

since I wanted this thread to be free for everyone to add their Qs n we

can have all good Qs on Integration piled up here

NOTE: There is no rule that u need to add Qs only after all the previous ones r answered !!!

But Plz let's restrict the max no. of qs that can remain unanswered at a time to be 5

So , Here we go to become perfect in INTEGRATION for IIT JEE

REQUEST : Do not post Qs out of IIT JEE level

1
RAY ·

yes dats wht!!but u cant go abt chking every point whether its differntiable or not..??????

4
UTTARA ·

@Kartick No. ur Qs I mean it's qs no 4

@Rohit : U know easily that it's differentiable over [-∞,0] & [0, ∞]

but not [-∞,0] U [0,∞]

1
kartick sharma ·

CAN ANYONE GET IT!!!!!!11

4
UTTARA ·

@Kartick what's f here ?????

u din't mention any f in the Qs na?????

1
kartick sharma ·

it is just a function

66
kaymant ·

@uttara
you wrote in #6:
"Only differentiable functions can be integrated "
Where did you learn this?
You further continue in the next post, saying:
"
f'(x) = 2x ex2

LHL ≠RHL

Hence , the function is not differentiable & thus not integrable "

How did you get LHL ≠RHL?

1
kartick sharma ·

somebody get mein ques.

4
UTTARA ·

@Kaymant : Sir ,

I learnt from a text book published by " Cengage Learning " in an Assertion - Reasoning Qs

Is it wrong ??

Coming to the function ex2

f'(x) = 2x ex2

f'(x) < 0 , for x -> 0- ----- LHL

f'(x) > 0 , for x -> 0+ ----- RHL

LHL ≠RHL
So , not differentiable

4
UTTARA ·

Sir plz correct me if I'm wrong
I'm unable to identify the mistake

4
UTTARA ·

All integrable functions r differentiable & converse

R they TRUE?????????

62
Lokesh Verma ·

No all integrable functions are not differentiable..

but all continuous functions are differentiable.. Integrable (God knows what is going in my head :D :P

4
UTTARA ·

Sir so can't we say that a non differential function is non integrable???

62
Lokesh Verma ·

http://en.wikipedia.org/wiki/Weierstrass_function

I think you can read this for a function which is continuous but not differentiable anywhere....

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