Messages posted by puneet

Open the series of cosx e^xand e^-xby power series method .....

Now use two concepts .. these are to be used in general while solving such questions

First the limit has to exist so the constant and coefficeint with x have to be zero since we have xsinx in the denominator ...

Second the coefficent of x² term should give the limit .....

I hope this helps .. reply back to this post if things are not clear ..

cheers !!!

Let the two parts be x and y ..

So we have two equations

x + y = 30000

and 0.09x + 0.11y = 3060

Now write these equations as a matrix and we are done !!!

cheers

Well both Delhi and Kota are good places to do JEE preparation. Both places have many good coaching institutes. However what matters is the fact that u do hard work .. okay ..

Well the study material of Brilliant is better however the classroom coaching of Vidyamandir is better ..

Again such things are perceptions that a individual has .. all depends as to what u like ...
Also I will suggest that once u join the coaching institute then study material that those suggest you to do so that there is a better coordination between you and your classes ...

cheers

Well yes this is correct !!

If u want to find the range then this is also fine ... all depends on what the question demands !!

This answer seems to be perfecto !!! Gr8 work done !!

The books which represent sgn(x) as mod(x)/x have defined it wrong. The actual definition is as follows :

sgn(x) = mod(x)/x when x

0

= 0 when x = 0

Now the thing should be hopefully clear ......

Cheers

It is okay dear ... the syllabus for iit do not chnage much .... or let me put it this way that even if it changes the books remain the same ... a new edition of M.L. khanna wud just have a new cover and nothing more than that .. so u can use the book u have purchased and there is no need to worry about ...

cheers

Gr8 answer ... rahul gr8 work done ..

cheers

hiiii

All the above suggested solutions are valid ..

See the key point is that u try to understand the concepts .. use some book say Arihant's book and start going through the theory of one chapter, once u know the theory then start solving problems ... going from easy to hard level .

While u solve problems focus on the concepts rather than the craming of way to solve the problems ... gradually u will start understanding the topics .. n u will not face any problem ..

Keep confidence in urself ... cheerooo

Put cos 2x = 1 / t

So, dx = dt / ( 2t². sin 2x)

so,

cos2x/sinx =

dt / ( 2t². 2sin²x) *

t * cosx

=

dt /

2 * t(t-1)

t+1

Now put t + 1 = p²

So,

cos2x/sinx =

2* dp / (p² - 1)*( p² - 2 )

=

2* dp / ( p² - 2 ) -

2* dp / ( p² - 1 )

Now these integrals can be easily intergated and thus we are done by resubstituting the values of p.

Cheers !!!!!!!!!!!!

y = log₁₀ x + log _x 10 + log _xx + log₁₀ 10
= log_ex / log_e10 + log_e10/log_ex + 1 + 1

dy/dx = 1 / (x * log_e10) - log_e10/((log_ex)²* x) + 0
= 1 / (x * log_e10) - log_e10/((log_ex)²* x)

cheers !!!!!

Correct answer .... well done !!!

The answer is C since we do not know that the force is applied in which direction and what is the direction of the displacement.

Note that the work done if F.d !!!!

cheers

Absolutely correct answer !!!! good work !!!!

Thank god u got it ........

Ooooooops hmm how do I explain ?? hehe ... try to take a simple example let us suppose the word in LAMA and we need to make 2 letter words from that. OKAY ??

So let us see ... by using the previous approach

We will find coefficeint of x²in the expression

2! (1 + x)²(1 + x + x²/2)

So we find coefficeint of x²in ( 1 + x² + 2.x).(1 + x + x²/2)

The terms corresponding to x² are 2! ( 1 + 2.1 + 1/2)x²

which is 7.

Now see the normal way the two letter words can be

AA, AL, AM, LA, LM, MA, ML

which are 7 in number so the approach works okay??

The expression will change if u make 5 letter words .. in this case u will replace 4! by 5! and find coefficiet of x^5.

okay ... cheers

okay let me explain ... first of all do not use that word SIR .. just a kid like u ... may made it earlier to IIT thats it . ok

Now about the approach .. see the letter E can appear in a four letter word for one , two or three times.. OKay ?? Now if the letter E appears 3 times then we need to divide by factorial(3) since otherwise we are counting redundant case.

So note that the x^3 has been divided by factorial(3) which is 6.

Similarily for other letters. Try to understand that x^n denotes that the letter appears n times in the word. Now is it clear ???

Well yes there is one more method where u actually take case and see that whether we have taken all different letters or some letters are alike and so on.

However the method described above is simple as u do not need to worry about the cases. The answer will automatically come. DO you understand the approach that has been used above ??

Great work done this a absolutely correct approach !!!!!!!!!!

I hope ruhi this helps u !!

See, in a cone the area of the disc at any distance from the top is varying and also the rate is varying. So the integral is not a two dimensional integration. And thus the book says that the integration cannot be done. Now for the cylindrical flow the area is not varying it is a constant that is the face area of the cylinder. Ok?? Thus it is written as A.

Now good book for thermal physics, I always will make one comment use H.C Verma. It is the best book. Right ???

Take things easy and try to solve some easy questions so that it make your concepts strong before going for hard problems. Okay.

cheers

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