xét x> 2
x^2 +x-12>0 {1+48=49)
\(\left[{}\begin{matrix}x< -4\\x>\dfrac{6}{2}=3\end{matrix}\right.\)
xét x<2
x^2 -x-8 >0 {1+33=34
\(\left[{}\begin{matrix}x< \dfrac{1-\sqrt{33}}{2}\\x>\dfrac{1+\sqrt{33}}{2}\end{matrix}\right.\)
Kết luận
\(\left[{}\begin{matrix}x< \dfrac{1-\sqrt{33}}{2}\\x>3\end{matrix}\right.\)
