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Mathematics 6 Online
OpenStudy (goformit100):

Integrate :-

OpenStudy (goformit100):

\[\int\limits \frac{ \sin x }{ x } dx\]

OpenStudy (anonymous):

looks like you wrote it

OpenStudy (nincompoop):

isn't that the integral already?

OpenStudy (goformit100):

Please Read the question carefully.

OpenStudy (kainui):

This is much easier if there are bounds on it, like from 0 to infinity.

OpenStudy (kainui):

Otherwise, you might just have to resort to integrating the power series. I don't think this one's a nice one.

OpenStudy (goformit100):

This question is from indefinite integration.

OpenStudy (kainui):

GOOD LUCK! lol

OpenStudy (anonymous):

As far as I know, this integral can't be done as written. You can approximate it by expanding sin(x) and then simplifying the expression, but it'll be an infinite series.

OpenStudy (kainui):

I think if it was easy, wolfram alpha wouldn't be giving it a special name. http://www.wolframalpha.com/input/?i=integral%20sinx%2Fxdx&t=crmtb01

OpenStudy (anonymous):

i thought the question said "write the integral" which is about what you can do

OpenStudy (anonymous):

unless you want to expand \(\sin(x)\) in a power series, divide by \(x\) and then integrate term by term

OpenStudy (goformit100):

please help me to solve this.

OpenStudy (anonymous):

The question is to actually integrate it, it looks like. This can't be done exactly in closed form. The closest you can get is by writing sin(x) as: \[\sin(x)=x-\frac{x^3}{3!}+\frac{x^5}{5!}-...\] Then simplify by dividing each term by x, then integrate. There will be a pattern, but there are an infinite number of terms, and no way to really simplify it.

OpenStudy (goformit100):

didn't get it

OpenStudy (anonymous):

what @Vandreigan is saying is that you are not going to get a nice closed form for this integral some function \(F\) with \(F'(x)=\frac{\sin(x)}{x}\)

OpenStudy (anonymous):

just because you write some integral, doesn't mean you can find it in a nice closed form

OpenStudy (juanpablojr):

f(x) = (1/x)cos x - (1/x²)sinx + C To make it easier to differentiate, factor (1/x). f(x) = (1/x) [cos(x) - (1/x)sin(x)] + C Differentiate using the product rule, noting that d/dx (1/x) = -1/x^2 gives us f'(x) = (-1/x^2) [cos(x) - (1/x)sin(x)] + (1/x) [-sin(x) - [(-1/x^2)sin(x) + (1/x)cos(x)] ] f'(x) = -cos(x)/x^2 + sin(x)/x^3 - sin(x)/x + sin(x)/x^2 - cos(x)/x And as you can see, it looks nothing like sin(x)/x.

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