Find .Notice that t3 becomes simpler when differentiated (where as e3t mostly unchanged when differentiated or interchanged) so u = dv = integration by parts gives The integral that we obtained ,is simple than the original integral but is still not obvious. therefore, we use integration by parts a second time with u = t and dv = e3tdv, then dv = Putting this equation 2, we get Solution sry im unable to see the question clearly...please post it separetely so that i can answer them for sure!.