Решите систему уравнений а) {3x+y=7 {9x-2y=1 В) {4x-y=10 {x=2y-1

$\left \{ {{3x+y=7} \atop {9x-2y=1}} \right. \\\\ \left+ \{ {{6x+2y=14} \atop {9x-2y=1}} \right.$
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15x = 15
x = 1
y = 7 - 3x = 7 - 3 * 1 = 7 - 3 = 4
Ответ : (1 ; 4)

$\left \{ {{4x-y=10} \atop {x=2y-1}} \right.\\\\ +\left \{ {{-8x+2y=-20} \atop {x-2y=-1}} \right.$
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- 7x = - 21
x = 3
y = 4x - 10 = 4 * 3 - 10 = 12 - 10 = 2
Ответ : (3 ; 2)