Advanced Linear Algebra
《Advanced Linear Algebra》 · 第 36 页 · Chapter 1「Vector Spaces」
Definition Let $S$ be a nonempty subset of a vector space $V$. A linear combination of vectors in $S$ is an expression of the form $a_1v_1+\cdots+a_nv_n$, where $v_1,\ldots,v_n\in S$ and $a_1,\ldots,a_n\in F$.