Để pt có nghiệm thì [tex]\Delta ^{'}\geq 0[/tex] [tex]\Leftrightarrow \left [ 2\left ( m-2 \right ) \right ]^{2} -(m+4)\geq 0\Leftrightarrow 4m^{2}-16m+16-m-4\geq 0\Leftrightarrow x\leq \frac{17-\sqrt{97}}{8} ,x\geq \frac{17+\sqrt{97}}{8}[/tex]
