Linear combination and spam
combination:
$$
\overrightarrow{v_1}, \overrightarrow{v_2}, \overrightarrow{v_3} \cdots \overrightarrow{v_n} \in \mathbb{R}^n c_1 \overrightarrow{v_1}+c_2 \overrightarrow{v_2}+\cdots+c_n \overrightarrow{v_n}\left[\left(c_1 \rightarrow c_n\right) \in \mathbb{R}\right]
$$span: $\vec{a}, \vec{b} \in \mathbb{R}$