3) B) x²+2x = x²+24; 2 7 г) 3x²+x - 2-7x = 3x²+17 . 4 5 10

в) $$\frac{x^2 + 2x}{2} = \frac{x^2 + 24}{7}$$

$$7(x^2 + 2x) = 2(x^2 + 24)$$

$$7x^2 + 14x = 2x^2 + 48$$

$$5x^2 + 14x - 48 = 0$$

$$D = 14^2 - 4 \cdot 5 \cdot (-48) = 196 + 960 = 1156 = 34^2$$

$$x_1 = \frac{-14 + 34}{10} = 2$$

$$x_2 = \frac{-14 - 34}{10} = -4.8$$

г) $$\frac{3x^2 + x}{4} - \frac{2 - 7x}{5} = \frac{3x^2 + 17}{10}$$

Умножим обе части уравнения на 20:

$$5(3x^2 + x) - 4(2 - 7x) = 2(3x^2 + 17)$$

$$15x^2 + 5x - 8 + 28x = 6x^2 + 34$$

$$9x^2 + 33x - 42 = 0$$

$$3x^2 + 11x - 14 = 0$$

$$D = 11^2 - 4 \cdot 3 \cdot (-14) = 121 + 168 = 289 = 17^2$$

$$x_1 = \frac{-11 + 17}{6} = 1$$

$$x_2 = \frac{-11 - 17}{6} = -\frac{14}{3}$$

Ответ: в) $$x_1 = 2$$, $$x_2 = -4.8$$, г) $$x_1 = 1$$, $$x_2 = -\frac{14}{3}$$