My textbook states:
The function $$u(t) = t^2$$
is a solution to the IVP:
$$u'(t) = 2\sqrt{|u(t)|}\hspace{30pt}u(0) =0$$
and I'm a little bit confused, since $u'(-10) = -20 \neq 20 = 2\cdot10 = 2\cdot\sqrt{100} = 2\cdot\sqrt{(-10)^2}$. Am I missing something?