x(x+2) + (х +5)^2 при х=-\frac{3}{8}

Решим:

$$x(x+2) + (x+5)^2 = x^2 + 2x + x^2 + 10x + 25 = 2x^2 + 12x + 25$$

Подставим $$x=-\frac{3}{8}$$

$$2\cdot(-\frac{3}{8})^2 + 12(-\frac{3}{8}) + 25 = 2\cdot\frac{9}{64} - \frac{36}{8} + 25 = \frac{9}{32} - \frac{18}{4} + 25 = \frac{9 - 18\cdot8 + 25\cdot32}{32} = \frac{9 - 144 + 800}{32} = \frac{665}{32} = 20\frac{25}{32}$$

Ответ: $$20\frac{25}{32}$$