\(\Leftrightarrow x^2-5x+7=-2m\)
Xét \(f\left(x\right)=x^2-5x+7\) trên \(\left[1;5\right]\)
\(f\left(1\right)=3\) ; \(f\left(5\right)=7\) ; \(f\left(-\frac{b}{2a}\right)=f\left(\frac{5}{2}\right)=\frac{3}{4}\)
\(f\left(x\right)_{min}=\frac{3}{4}\) ; \(f\left(x\right)_{max}=7\)
\(\Rightarrow\frac{3}{4}\le-2m\le7\Rightarrow-\frac{7}{2}\le m\le-\frac{3}{8}\)