由条件知a1 a2 b线性相关，即行列式|a1 a2 b|=0，于是t=0。b=-a1+3a2Aa1=2a1，Aa2=3a2 Ab=A(-a1+3a2)=9a2-2a1，A^2b=A(9a2-2a1)=27a2-4a1，归纳可得A^nb=3^(n+1)a2-2^na1
