Let v=(12)v = \begin{pmatrix} 1 \\ 2 \end{pmatrix}v=(12) be an eigenvector of matrix B=(31a2)B = \begin{pmatrix} 3 & 1 \\ a & 2 \end{pmatrix}B=(3a12). What is the value of aaa?
a=−4a = -4a=−4
a=4a = 4a=4
a=2a = 2a=2
a=−2a = -2a=−2