微分方程y″-6y′+9y=e3x(x+1)的特解形式應(yīng)設(shè)為:()
A.xe3x(ax+B. B.x2e3x(ax+B. C.e3x(ax+B. D.ae3xx3
A.Acosx+Bsinx B.x(Acosx+Bsinx) C.x2(Acosx+Bsinx) D.(Ax2+B.sinx+Cxcosx
A.(Ax+B.cos2x+(Cx+D.sin2x B.(Ax2+Bx)cos2x C.Acos2x+Bsin2x D.x(Ax+B.(cos2x+sin2x)