[tex]\frac{x^4+x^2+1}{x^2}=\frac{x^2+x+1}{x }[/tex]
[tex]\frac{x^{4}+x^{2}+1}{x^{2}}=\frac{x^{2}+x+1}{x} <=> \frac{(x^{2}+x+1)^{2}-2(x^{3}+x+x^{2})}{x^{2}}=\frac{x^{2}+x+1}{x}[/tex]
[tex](\frac{(x^{2}+x+1)}{x})^{2}-\frac{2(x^{2}+x+1)}{x}=\frac{x^{2}+x+1}{x} <=> (\frac{(x^{2}+x+1)}{x})^{2} -3\frac{x^{2}+x+1}{x}=0 <=> t^{2}-3t=0[/tex] => tự làm