Question

помогите плиз с математикой​

Answer 1

Ответ:

1

$\left \{ {{x - y = 1} \atop {y + x = - 5} } \right. \\ \\ \left \{ {{x = 1 + y} \atop {x + y = - 5} } \right. \\ \\ 1 + y + y = - 5 \\ 2y = - 6 \\ y = - 3 \\ \\x = - 3 + 1 = - 2$

Ответ: (-2; -3)

2

$\left \{ {{2x + y = 6} \atop {x - 2y = 13} } \right. \\ \\ \left \{ {{y = 6 - 2x} \atop {x - 2y = 13} } \right. \\ \\ x - 2(6 - 2x) = 13 \\ x - 12 + 4x = 13 \\ 5x = 25 \\ x = 5 \\ \\ y = 6 - 2 \times 5 = 6 - 10 = - 4$

Ответ: (5;-4)

3

$\left \{ {{2x - 2y = 5} \atop {6x + 3y = 6} } \right. \\ \\ \left \{ {{2x = 5 + 2y} \atop {3 \times 2x + 3y = 6} } \right. \\ \\ 3(5 + 2y) + 3y = 6 \\ 15 + 6y + 3y = 6 \\ 9y = - 9 \\ y = - 1 \\ \\ x = \frac{5 + 2y}{2} \\ x = \frac{5 - 2}{2} = 1.5$

Ответ: (1,5; -1)

4

$\left \{ {{ - 2x + y = 4} \atop {7x - y = 1} } \right. \\ \\ \left \{ {{y = 4 + 2x} \atop {7x - y = 1} } \right. \\ \\ 7x - (4 + 2x) = 1 \\ 7x - 4 - 2x = 1 \\ 5x = 5 \\ x = 1 \\ \\ y = 4 + 2 = 6$

Ответ: (1;6)

5

$\left \{ {{x - y = 7} \atop {5x - 3y = 1} } \right. \\ \\ \left \{ {{x = 7 + y} \atop {5x - 3y = 1} } \right. \\ \\ 5(7 + y) - 3y = 1 \\ 35 + 5y - 3y = 1 \\ 2y = - 34 \\ y = - 17 \\ \\ x = 7 -17=-10$

Ответ: (-10; -17)