The integral is .
Definition of an improper integral :
\If exists for every number
, then
provoded this limit exists (as a finite number).
Consider .
Let .
Differentiate on each side with respect to .
Boundaries : from to
.
Substitute corresponding values in equation .
Power rule of integral :.
.
Since (finite value), the integral is convergent.
The integral is convergent and the value is .