I am having trouble with this definite integral, especially since it involves infinity, and the way my professor explained the process has me completely baffled. Any help is very much appreciated, last time one of the members of this forum explained the process better than my professor! Thank you for any help !

P.s. I haven't figured out how to display the definite integral with the math tag sorry about that...

Definite Integral (a= 2 and b=oo infinity) of