Question

Simple Integration ;

1/2 ∫ [cos (2x +3) + cos (2x^2 +5) dx ]

Answer 1

nothing simple about this one

Answer 2

no all that simple

Answer 3

wt heck is this can someone plz explain this to me too

Answer 4

I don't understand this either

Answer 5

i don't think you will find the closed form for this integral

Answer 6

http://www.wolframalpha.com/input/?i=1%2F2+%E2%88%AB+%5Bcos+%282x+%2B3%29+%2B+cos+%282x%5E2+%2B5%29+dx+%5D

Answer 7

My answer is 1/2 [ 1/2 sin (2x + 3) + 1/4x sin (2x^2 +5) ] . Its direct question rite...I just want to clear it .

Answer 8

oh no that is not right. you can check by differentiating and see that you do not get the integrand

Answer 9

I'm sorry you can't integrate the second cos like that. This question is quite difficult.

Answer 10

wolfram is no help here. it is telling you that the integral is an integral

Answer 11

yh, it is. Fresnel integral. Interesting

Answer 12

Actually my problem is ;

To use ∫ cosAcosB dx = 1/2 ∫ cos (A+B) + cos(A-B) dx formula into FOURIER SERIES QUESTION.....

Any suggestions...??

Answer 13

"fresnel" means
\[\int_0^x \sin(t^2)dt\] so this is really no help at all

Answer 14

mrexp21 is that the whole question?

Answer 15

yh, how can an integral be an integral ?

Answer 16

well, and integral IS an integral. how can it not be one?

Answer 17

interesting!

Answer 18

just because you write
\[\int_a^xf(t)dt\] doesn't mean you can find the "closed form" of such a thing as an elementary function

Answer 19

this is a terrible one

Answer 20

Okay....

Im trying to do Fourier Series over here....

Finally it will end up with integrals....

Lets say , if I get this kind of integral type ;

∫ cos A cos B -----> How to integrate this type of function ?

So , based on trignometric identity , it should be converted to 1/2 ∫ cos (A+B) + cos (A-B) dx .