[tex]16x {}^{2} - 81 \\ 4 {}^{2} x {}^{2} - 9 {}^{2} \\ (4x ) {}^{2} - 9 {}^{2} \\ (4x - 9) \times (4x + 9) \\ [/tex]
[tex]16x^2-81\\\left(4x\right)^2-9^2\\\\\boxed{\boxed{\left(4x+9\right)\left(4x-9\right)}}[/tex]
[tex]\\\boxed{ANDROIDE}[/tex]
