\(\Rightarrow x_{1,2}=\frac{4\pm\sqrt{12}}{2}\).Ta lại có: \(A=\frac{x^4+x^2+1}{x^2}=\left(x+\frac{1}{x}-1\right)\left(x+\frac{1}{x}+1\right)\)
Tại \(x=\frac{4+\sqrt{12}}{2}\) thì \(A=\left(\frac{4+\sqrt{12}}{2}+\frac{1}{\frac{4+\sqrt{12}}{2}}-1\right)\left(\frac{4+\sqrt{12}}{2}+\frac{1}{\frac{4+\sqrt{12}}{2}}+1\right)\)
Tại \(x=\frac{4-\sqrt{12}}{2}\) thì \(A=\left(\frac{4-\sqrt{12}}{2}+\frac{1}{\frac{4-\sqrt{12}}{2}}-1\right)\left(\frac{4-\sqrt{12}}{2}+\frac{1}{\frac{4-\sqrt{12}}{2}}+1\right)\)