Question

Найдите решение систем уравнений способом подстановки​

Answer 1

$1) - y + 0.5 + 2y = 0.3 \\ y + 0.5 = 0.3 \\ y = 0.3 - 0.5 \\ y = - 0.2 \\ \\ x = - y + 0.5 = - ( - 0.2) + 0.5 = 0.2 + 0.5 = 0.7$

$- x - 6. 9- 8x = 83.1 \\ - 9x = 83.1 + 6.9 \\ - 9x = 90 \\ x = 90 \div ( - 9) \\ x = - 10 \\ y = - x - 6.9 = - ( - 10) - 6.9 = 10 - 6.9 = 3.1$

$21x + 0.9 - x = - 15.1 \\ 20x = - 15.1 - 0.9 \\ 20x = - 16 \\ x = \frac{ - 16}{ - 20} \\ x = \frac{4}{5} \\ x = 0.8 \\ \\ y = 0.9 - x = 0.9 - 0.8 = 0.1$