Verified answer

Объяснение:

а) n² - 81 = n² - 9² = ( n - 9 ) × ( n + 9 )

[tex] b)\frac{4}{25} - \: 4m {}^{2} = \frac{4}{25} \times (1 - 25 {}^{2} ) = \frac{4}{25} \times (1 - 5m) \times (1 + 5m)[/tex]

в) 16c² - 9d² = 4²с² - 3²d² = ( 4c )² - ( 3d )² = ( 4c - 3d ) × ( 4c + 3d )