1. The problem statement, all variables and given/known data I need to find the integral of (e^3x)cos(2x) 2. Relevant equations 3. The attempt at a solution I tried using different trig identities for cos(2x) to get a better equation and then tried to do few versions using the integration by parts but they all kept getting more complicated. Also I need to find cos(sqrt.x). Im not sure how to do the integration by parts since I have only one piece of equation. Just setting X^1/2=u won't work couse du part has x in it which I can't take out of the integral.