I observe that if I execute in the url of wolfram alpha the integral of the function (3/x^2)Sin(x)Sin(x/3) with the limits between zero and infinity:

integrate (3/x^2)sin(x)sin(x/3) from 0 to inf

I get a correct PI/2 value, but if I do it on my computer with my Mathematica, it does not return anything, as a result shows me the same integral.

Integrate [(3 / x ^ 2) Sin[x] Sin[x / 3], {x, 0, inf}]

Why? Is it because my computer?

Thank you


closed as off-topic by Szabolcs, Kuba Aug 25 '17 at 8:23

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  • "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – Szabolcs, Kuba
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  • $\begingroup$ Syntax error: infinity is represented as Infinity, not inf. $\endgroup$ – Szabolcs Aug 25 '17 at 8:15

You should use Infinity rather than inf.

Integrate[(3/x^2) Sin[x] Sin[x/3], {x, 0, Infinity}]
  • $\begingroup$ Thank you very much; I had try with inf and with the symbol; I will try with infinity. $\endgroup$ – Perico Cruel Aug 25 '17 at 8:26

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