Respuesta :

[tex]81x^2\text{ - 25}[/tex]

Apply difference of two square

[tex]x^2-y^2\text{ = (x - y)(x + y)}[/tex]

[tex]\begin{gathered} 81x^2\text{ - 25} \\ =(9x)^2-5^2 \\ \text{Apply difference of two square} \\ =\text{ (9x - 5)(9x + 5)} \end{gathered}[/tex]