Question

Решите систему уравнений {3x-4y=2 2x+y=-6

Answer 1

$\left \{ {{3x-4y=2} \atop {2x+y=-6}} \right. \\\\\left \{ {{3x-4y=2} \atop {y=-6-2x}} \right. \\\\3x-4(-6-2x)=2\\\\x=-2\\\\y=-6-2*(-2)\\\\y=-2\\\\(x,y)=(-2,-2)\\\\\left \{ {{3*(-2)-4*(-2)=2} \atop {2*(-2)+(-2)=-6}} \right.$

$\left \{ {{2=2} \atop {-6=-6}} \right. \\\\(x,y)=(-2,-2)$

Answer 2

$\displaystyle\bf\\\left \{ {{3x-4y=2} \atop {2x+y=-6} \ |\cdot 4} \right.\\\\\\+\left \{ {{3x-4y=2} \atop {8x+4y=-24}} \right.\\ ----------\\11x=-22\\\\x=-2\\\\y=-2x-6=-2\cdot(-2)-6=4-6=-2\\\\y=-2\\\\Otvet:(-2 \ ; \ -2)$