Linear Dependence

Two functions $f_{1}$ and $f_{2}$ are linearly independent if $c_{1} f_{1} + c_{2} f_{2} = 0$ if and only if $c_{1} = c_{2} = 0$

The 2 functions are linearly dependent otherwise

$\exists$ $c_{1}, c_{2}$ where $c_{1} f_{1} + c_{2} f_{2} = 0$ and they're not both $0$