a: \(\Leftrightarrow x^2=m-1\)
\(\Leftrightarrow x\in\left\{\sqrt{m-1};-\sqrt{m-1}\right\}\)
b: \(\Delta=m^2-4\cdot2\cdot\left(-m^2\right)=8m^2+m^2=9m^2\)>=0
Do đó: Phương trình có hai nghiệm phân biệt là:
\(\left\{{}\begin{matrix}m_1=\dfrac{-m-3m}{4}=-\dfrac{4m}{4}=-1\\m_2=\dfrac{-m+3m}{4}=\dfrac{2m}{4}=\dfrac{m}{2}\end{matrix}\right.\)