Помогите с неравенствами

Решите задачу:

$\displaystyle \sqrt{x-1}<-4\quad \Leftrightarrow \quad \left \{ {{-4 \geq 0} \atop {x-1<16}} \right. \quad \Rightarrow \quad \left \{ {{\varnothing} \atop {x<17}} \right. \quad \Rightarrow \quad \varnothing$

$\displaystyle \sqrt{x-3}\leq 0 \quad \Leftrightarrow \quad \left \{ {{x-3\geq 0} \atop {x-3\leq 0}} \right. \quad \Rightarrow \quad \left \{ {{x\geq 3} \atop {x\leq 3}} \right. \quad \Rightarrow\quad \boxed{x=3}$