From $ b = -2 $, substitute into 2: $ c = 6 + 2a $. Let $ a $ be a free variable. Choosing $ a = 0 $, then $ c = 6 $. Thus, $ \mathbfv = \beginpmatrix 0 \\ -2 \\ 6 \endpmatrix $. Final answer: $ \boxed\beginpmatrix 0 \\ -2 \\ 6 \endpmatrix $.**Question 1: - Portal da Acústica