1.$\sqrt{x^2-5x+4}\leq x+1$
2.$\sqrt{x+4}+1> \sqrt{2x-6}$
3.$\left | x^2-x \right |\leq 2$
3.
$\left | x^2-x \right |\leq 2\Rightarrow \begin{bmatrix} x^2-x\leq 2\\ x^2-x\geq -2 \end{bmatrix} \Rightarrow \begin{bmatrix} x^2-x-2\leq 0\\ x^2-x+2\geq 0 \end{bmatrix} \Rightarrow 2\geq x\geq -1$