Question

решите систему уравнений x+y=2 y^2-x^2=12

Answer 1

$\left \{ {{x+y=2} \atop { y^{2}- x^{2} =12 }} \right.\\\\ \left \{ {{x+y=2} \atop {(y-x)(y+x)=12}} \right.\\\\ \left \{ {{y+x=2} \atop {(y-x)*2=12}} \right. \\\\ +\left \{ {{y+x=2} \atop {y-x=6}} \right.$
__________
  2y = 8
  y = 4
  x = 2 - y = 2 - 4 = - 2
Ответ: (- 2 ; 4)