微分方程dy/dx+3y=(x^5)*(e^(-3x))如何求解?

y'+3y = x^5*e^(-3x) 是一阶线性微分方程,通解是
y = e^(-∫3dx)[C+∫x^5e^(-3x)e^(∫3dx)dx]
= e^(-3x)[C+∫x^5dx]
= e^(-3x)(C+x^6/6)