Considere as matrizes

!$ A = { \begin{bmatrix}1\,\,\,\,\,\,a\\2\,\,\,-1 \end{bmatrix}}, B= { \begin{bmatrix}1\,\,\,\,\,\,b\\b\,\,\,\,1 \end{bmatrix}} !$ e

!$ C = { \begin{bmatrix}cos\,\theta\,\,\,\,\,\,sen\,\theta\\-sen\,\theta\,\,\,cos\,\theta \end{bmatrix}} !$. Julgue a afirmativa:

Item 2 - Para b = 2, !$ v= { \begin{pmatrix} 1\\2 \end{pmatrix}} !$