Question

Помогите!! Мне сдавать через 10 минут!!!! Даю 30 баллов!!!!

Answer 1

Ответ:

$\frac{3 {a}^{2} + 6 }{a {}^{3} + 1 } - \frac{3}{a {}^{2} - a + 1} - \frac{1}{a + 1} = \\ = \frac{3 {a}^{2} + 6}{(a + 1)(a {}^{2} - a + 1)} - \frac{3}{a {}^{2} - a + 1} - \frac{1}{a + 1} = \\ = \frac{3 {a}^{2} + 6 - 3(a + 1) - ( {a}^{2} - a + 1)}{(a + 1)(a {}^{2} - a + 1)} = \\ = \frac{3 {a}^{2} + 6 - 3a - 3 - {a}^{2} + a - 1 }{a {}^{3} + 1} = \\ = \frac{2 {a}^{2} - 2a + 2 }{a {}^{3} + 1} = \frac{2( {a}^{2} - a + 1)}{(a + 1)(a {}^{2} - a + 1)} = \\ = \frac{2}{a + 1} \\ \\ a = - 1.4 \\ \\ \frac{2}{1 - 1.4} = \frac{2}{ - 0.4} = 2 \times ( - \frac{5}{2} ) = - 5$