Maybe this is something basic but I am not familiar with the term "linear span" and in one question it mentions
the linear span of the functions $f_n(t) = e^{nt}$, $n = 0,1,2,...$ $t \in [a,b]$
What I understood is linear span is the set of linear combination of all elements but I am still unable to understand what that set is.
Thank you very much.