4.3 Linearly Independent Sets; Bases 229
19. Let $v_1 = \begin{bmatrix} 4 \ -3 \ 7 \end{bmatrix}$, $v_2 = \begin{bmatrix} 1 \ 9 \ -2 \end{bmatrix}$, $v_3 = \begin{bmatrix} 7 \ 11 \ 6 \end{bmatrix}$, and $H = \text{Span} \{v_1, v_2, v_3\}$. It can be verified that $4v_1 + 5v_2 - 3v_3 = 0$.
Use this information to find a basis for $H$. There is more than
one answer.