Pt có hai nghiệm dương <=>\(\left\{{}\begin{matrix}\Delta>0\\S>0\\P>0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}4m^2-4\left(m^2-1\right)=4>0\left(lđ\right)\\2m>0\\m^2-1>0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}m>0\\\left[{}\begin{matrix}m< -1\\m>1\end{matrix}\right.\end{matrix}\right.\) => m>1
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