Show that
- if f is continuous
$\frac{d}{dx}(f(x)\delta(x)) = f(0)\delta'(x)$
- if f is differentiable, use Leibnitz rule to conclude that
$\frac{d}{dx}(f(x)\delta(x)) = f'(x)\delta(x)+f(x)\delta'(x)$
I stuck at starting the proof. Should I use integration to do both proof?