Question

помогите!!!!!!!!!!!!!!!!​

Answer 1

{ х - 2у = - 2

{ 7х + 12у = 7

Выразим х через у ↓

{ х = 2у - 2

{ 7х + 12у = 7

Составим уравнение ↓

7(2у - 2) + 12у = 7

14у - 14 + 12у = 7

14у + 12у = 7 + 14

26у = 21

у = 21/26 ≈ 0,808

Подставим значение у в любое уравнение ↓

х - 2 * 21/26 = - 2

х - 42/26 = - 2

х = - 2 + 42/26

х = - 5/13 ≈ - 0,385

Ответ : (- 0,385; 0,808)

Answer 2

$\displaystyle\bf\\\left \{ {{x-2y=-2} \atop {7x+12y=7}} \right. \\\\\\\left \{ {{x=2y-2} \atop {7\cdot(2y-2)+12y=7}} \right.\\\\\\\left \{ {{x=2y-2} \atop {14y-14+12y=7}} \right. \\\\\\\left \{ {{x=2y-2} \atop {26y=21}} \right. \\\\\\\left \{ {{x=2y-2} \atop {y=\dfrac{21}{26} }} \right. \\\\\\\left \{ {{x=2\cdot\dfrac{21}{26} -2} \atop {y=\dfrac{21}{26} }} \right. \\\\\\\left \{ {{x=\dfrac{21}{13}- 2} \atop {y=\dfrac{21}{26} }} \right.$

$\displaystyle\bf\\\left \{ {{x=-\dfrac{5}{13} } \atop {y=\dfrac{21}{26} }} \right. \\\\\\\left \{ {{x\approx-0,385} \atop {y\approx0,808}} \right. \\\\\\Otvet:\Big(-0,385 \ ; \ 0,808\Big)$