[tex]27^{x}-27^{1-x}-16\left ( 3^{x}-\frac{3}{3^{x}} \right )+6< 0[/tex]
PT [tex]<=> 3^{3x}-\frac{27}{3^{3x}}-16.(3^{x}-\frac{3}{3^{x}})+6<0[/tex]
Đặt [tex]3^{x}=t (t>0)[/tex] => PT: [tex]t^{3}-\frac{27}{t}-16(t-\frac{3}{t})+6<0[/tex] => ... t =>....x