Consider the following vectors in $\mathbb{R}^3$:

$$v_1 = \left[ \begin{array}{c} 1 \\ 6 \\ 8 \end{array} \right] \qquad v_2 = \left[ \begin{array}{c} -3 \\ -6 \\ -21+\lambda \end{array} \right] \qquad v_3 = \left[ \begin{array}{c} -3 \\ -9 \\ -15 \end{array} \right]$$

The set $\lbrace v_1, v_2, v_3 \rbrace$ is linearly independent if and only if $\lambda \ne$ .