Linear Algebra Done Right
《Linear Algebra Done Right》 · 第 29 页 · Section 2A「Span and Linear Independence」，Definition 2.4
The set of all linear combinations of a list of vectors $v_1,\ldots,v_m$ in $V$ is called the span of $v_1,\ldots,v_m$, denoted by $\operatorname{span}(v_1,\ldots,v_m)$. In other words, $\operatorname{span}(v_1,\ldots,v_m)=\{a_1v_1+\cdots+a_mv_m:a_1,\ldots,a_m\in F\}$.