解：用分部积分法做∫ xe^4x dx (u = x, v' = e^4x, v = 1/4 e^4x)= (1/4)xe^4x - (1/4) ∫ e^4x dx= (1/4)xe^4x - (1/4)(1/4) e^4x + C= (1/4)xe^4x - (1/16)e^4x + C不明白可以追问，望采纳！
