Question

Решить интеграл ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

Answer 1

$\int \limits _0^{ \infty }x \sin(x) dx = </p><p>{\displaystyle \Im }( \int \limits _0^{ \infty }x {e}^{ix} dx) = \\ = {\displaystyle \Im }( x \frac{ {e}^{ix} }{i} |_{0}^{ \infty } - \int \limits _0^{ \infty } \frac{ {e}^{ix} }{i} dx) = {\displaystyle \Im }( x \frac{ {e}^{ix} }{i} |_{0}^{ \infty } - \frac{ {e}^{ix} }{ {i}^{2} }|_{0}^{ \infty }) = \\ = {\displaystyle \Im } ( - ix {e}^{ix} + {e}^{ix} )|_{0}^{ \infty } = ( {\displaystyle \Im }( {e}^{ix} ) - {\displaystyle \Re }(x {e}^{ix} )) |_{0}^{ \infty }= \\ = \sin(x) - x \cos(x) |_{0}^{ \infty } \rightarrow + \infty$

Ответ: интеграл расходится