Question

ПОМОГИТЕ!
Нужно решить методом подставки.
Только, пожалуйста, не из интернета. ​

Answer 1

Ответ:

${x}^{2} + 10xy + 25 {y}^{2} = 9 \\ x - 5y = 7 \\ \\ {x}^{2} + 10xy + 25 {y}^{2} = 9 \\ x = 7 + 5y \\ \\ {(7 + 5y)}^{2} + 10y(7 + 5y) + 25 {y}^{2} = 9 \\ x = 7 + 5y \\ \\ 49 + 70y + 25 {y}^{2} + 70y + 50 {y}^{2} + 25 {y}^{2} = 9 \\ x = 7 + 5y \\ \\ 100 {y}^{2} + 140y + 40 = 0 \\ x = 7 + 5y \\ \\ 5 {y}^{2} + 7y + 2 = 0 \\ x = 7 + 5y \\ \\ \sqrt{d} = 3 \\ y1 = - 1 \\ y2 = - 0.4 \\ \\ y1 = - 1 \\ x1 = 7 - 5 \\ y2 = - 0.4 \\ x2 = 7 - 2 \\ \\ y1 = - 1 \\ x1 = 2 \\ y2 = - 0.4 \\ x2 = 5$