\(f'\left(x\right)=4x^3+2\left(1-m^2\right)x=0\Rightarrow2x\left(2x^2+1-m^2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x^2=\dfrac{m^2-1}{2}\end{matrix}\right.\)
Pt có 3 nghiệm thực pb khi \(\dfrac{m^2-1}{2}>0\)
\(\Rightarrow\left[{}\begin{matrix}m>1\\m< -1\end{matrix}\right.\)
C đúng
