Reapeated Real and Complex Roots

Hi.

My book on the subject of differential equations tends to omit things from time to time, and one such thing - namely, how it is that we can show that if an auxiliary equation to an nth order DE with constant

coeffiecients has as its roots $\displaystyle m_1=m_2=...=m_n$, then the general solution is given by the linear

combination of the terms $\displaystyle e^{mx},x^{}e^{mx},x^{2}e^{mx},...,x^{n-1}e^{mx}$.

I know how to show this for $\displaystyle n=2$, but the general case I'm having a little trouble with. Any help?