In: Advanced Math
Prove that for an nth order differential equation whose auxiliary equation has a repeated complex root a+bi of multiplicity k then its conjugate is also a root of multiplicity k and that the general solution of the corresponding differential equation contains a linear combination of the 2k linearly independent solutions
e^(ax)cos(bx), xe^(ax)cos(bx), x^2e^(ax)cos(bx),..., x^(k-1)e^(ax)cos(bx)
e^(ax)sin(bx), xe^(ax)sin(bx), x^2e^(ax)sin(bx),..., x^(k-1)e^(ax)sin(bx)