# Second derivative of the absolute value functon

given $$x in mathbb {R ^ n}$$ I now have the first derivative of the absolute value function

$$frac {d | x |} {dx} = frac {x} {| x |}.$$

But what is the second derivation of it? I need it to calculate the second derivative for the function $$u: mathbb {R} ^ n rightarrow mathbb {R}$$

$$u (x) = | x | ^ alpha$$

With $$alpha> 0.$$