y'=(2x^2-5x+1) ' e^x+(2x^2-5x+1)(e^x)'
=(4x-5)e^x+(2x^2-5x+1)e^x
=(2x²-x-4)e^x那y=xsin2x呢y ‘=x’sin2x+x（sin2x）' =sin2x+2xcos2x