rút gọn bth sau.............................

$\text{b) (a + 2)(a - 2)(a² + 2a + 4)(a² - 2a + 4)}$

$\text{= [(a + 2)(a² - 2a + 4)][(a - 2)(a² + 2a + 4)]}$

$\text{= {(a + 2)[(a)² - a . 2 + (2)²]}{(a - 2)[(a)² + a . 2 + (2)²]}}$

$\text{= [(a)³ + (2)³][(a)³ - (2)³]}$

$\text{= (a³ + 8)(a³ - 8) }$

$\text{= (a³)² - (8)²}$

$\text{= $a^{6}$ - 64}$

$\textit{Ha1zzz}$