Question

Решите уравнения:
1)
2)
3)
4)

Answer 1

Ответ:

$1)8 - (x - 3)(x + 3) = 10 - (x - 1) {}^{2} \\ 8 - {x}^{2} + 9 = 10 - {x}^{2} + 2x - 1 \\ 8 + 9 - 10 + 1 = 2x \\ 8 = 2x \\ x = 4$

$2) {(2x + 1)}^{2} - {(2x - 3)}^{2} = 4(7x - 5) \\ 4 {x}^{2} + 4x + 1 - 4 {x}^{2} + 12x - 9 = 28x - 20 \\ 12x + 4x - 28x = 9- 20 - 1 \\ - 12x = - 12 \\ x = 1$

$3)x \div 15 = 2 \frac{1}{12} \div 14.5 \\ \frac{x}{15} = \frac{25 \times 2}{12 \times 29} \\ \frac{x}{15} = \frac{25}{174} \\ x = \frac{25 \times 15}{174} \\ x = \frac{25 \times 5}{58} \\ x = \frac{125}{58}$

$4) \frac{x}{2.3} = \frac{2.1}{9 \frac{6}{7} } \\ x = \frac{2.3 \times 2.1}{ \frac{69}{7} } \\ x = \frac{2 3 \times 21 \times 7}{69 \times 10 \times 10} \\ x = \frac{49}{100} \\ x = 0.49$