Chắc đề là \(y=x^2+8x+5m-24\)
\(\left\{{}\begin{matrix}a=-1< 0\\-\frac{b}{2a}=4\in\left[1;6\right]\end{matrix}\right.\)
\(\Rightarrow\max\limits_{\left[1;6\right]}f\left(x\right)=f\left(4\right)=5m-8\)
\(\Rightarrow5m-8=-1\Rightarrow m=\frac{7}{5}\)