English
For all x, (√x)^2 = max{x,0}.
Русский
Для любого x выполняется (√x)^2 = max{x,0}.
LaTeX
$$$(\sqrt{x})^2 = \max\{x,0\}$$$
Lean4
/-- Variant of `sq_sqrt` without a non-negativity assumption on `x`. -/
theorem sq_sqrt' : √x ^ 2 = max x 0 := by
rcases lt_trichotomy x 0 with _ | _ | _ <;>
grind [sqrt_eq_zero', sq_sqrt]
-- Add the rule for `√x ^ 2` to the grind whiteboard whenever we see a real square root.