∫ex(sin4x−41−cos4x)dx=∫ex(2sin2xcos2x−42sin22x)dx(∵sin2x=2sinxcosxandcos2x=1−2sin2x)=∫ex2sin2xcos2x2sin22xdx−∫ex42sin22xdx=∫excot2xdx−2∫excosec22xdx(∵cosecx=1sinx)integratingbyparts;=cot2x.∫exdx−∫[ddxcot2x.∫exdx]dx−2∫excosec22xdx=ex.cot2x+2∫excosec22xdx−2∫excosec22xdx(∵ddxcotx=−cosec2x)=ex.cot2x+C