## Elementary Linear Algebra 7th Edition

The set $W$ of all exponential functions $f(x)=a^{x}$ where $a>0$ is not a vector subspace of $C(-\infty, \infty)$.
The set $W$ of all exponential functions $f(x)=a^{x}$ where $a>0$ is not a vector subspace of $C(-\infty, \infty)$. Because it is not closed under neither scalar multiplication nor addition.