设a对应特征向量为μ
A^mμ=A^(m-1)Aμ=aA^(m-1)μ=...=a^mμ
设f(x)=b0x^n+b1x^(n-1)+...+b(n-1)x+bn
f(A)μ=[b0A^n+b1A^(n-1)+...+b(n-1)A+bnE]μ
=[b0a^n+b1a^(n-1)+...+b(n-1)a+bn]μ
=f(a)μ
即得证