Решите ,пожалуйста, 3 и 4 задания !!!

№3
$\frac{1}{(x - 2)(x + 2)} - \frac{1}{x - 2} - \frac{1}{x + 2} =$

$= \frac{1 - (x + 2) - ( x - 2)}{(x - 2)(x + 2)} = \frac{1 - x - 2 - x + 2}{ {x}^{2} - 4} =$

$= \frac{1 - 2x}{ {x}^{2} - 4}$

№4
$\frac{3 {a}^{2} + 6}{(a + 1)( {a}^{2} - a + 1) } - \frac{3}{ {a}^{2} - a + 1 } - \frac{1}{a + 1} =$

$= \frac{3 {a}^{2} + 6 - 3(a + 1) - ( {a}^{2} - a + 1) }{(a + 1)( {a}^{2} - a + 1) } =$

$= \frac{3 {a}^{2} + 6 - 3a - 3 - {a }^{2} + a - 1 }{(a + 1)( {a}^{2} - a + 1) } = \frac{2a^{2} + 2 - 2a}{(a + 1)( {a}^{2} - a + 1) } =$

$= \frac{2( {a}^{2} - a + 1)}{(a + 1)( {a}^{2} - a + 1)} = \frac{2}{a + 1}$

УДАЧИ;)