Bài 1:
Do \(ac< 0\Rightarrow\) pt luôn có 2 nghiệm pb trái dấu
Do \(x_1< x_2\Rightarrow x_1< 0< x_2\)
\(\Rightarrow\left\{{}\begin{matrix}\left|x_1\right|=-x_1\\\left|x_2\right|=x_2\end{matrix}\right.\)
\(\left|x_1\right|-\left|x_2\right|=16\)
\(\Leftrightarrow-x_1-x_2=16\)
\(\Leftrightarrow x_1+x_2+16=0\)
\(\Leftrightarrow m+9+16=0\Rightarrow m=-25\)
Bài 2:
\(ac< 0\Rightarrow\) pt có 2 nghiệm pb trái dấu
\(x_1>x_2\Rightarrow x_1>0>x_2\Rightarrow\left\{{}\begin{matrix}\left|x_1\right|=x_1\\\left|x_2\right|=-x_2\end{matrix}\right.\)
\(\left|x_1\right|-\left|x_2\right|=15\)
\(\Leftrightarrow x_1+x_2=15\)
\(\Leftrightarrow-\left(m+12\right)=15\)
\(\Rightarrow m=-27\)
