Question

Решите систему уравнений:
$\left \{ {{x-y=2 \atop {x^2-y^2=8}} \right.$

Answer 1

$\left \{ {{x-y=2 \atop {x^2-y^2=8}} \right. \Leftrightarrow \left \{ {{x-y=2 \atop {(x-y)(x+y)=8}} \right. \Leftrightarrow 2(x+y)=8; \Leftrightarrow x+y=4;$

$\left \{ {{x=2+y \atop {x+y=4}} \right. \Leftrightarrow 2+y+y=4; \Leftrightarrow y=1; \Leftrightarrow x=3;$