Reciprocal function

Let f be the reciprocal function:

$\forall x \in \mathbb{R}^*, \\f(x)=\frac{1}{x}$

I\ Calculate:

$1) f(1) \\2) f(-\frac{1}{2}) \\3) f(10^{-6}) \\4) f(\sqrt{2}) \\5)f(\frac{\sqrt{5}}{5})$

Note: If you end up with roots or fractions, keep the fraction/radical, don't give the decimal form.

II\ Demonstrate that, for any strictly positive real number x, that $\frac{1}{\sqrt{x}}=\frac{\sqrt{x}}{x}$