Question

решите систему y-x＝-3 x2-y2＝63​

Answer 1

$left { {{y-x=-3} atop {x^{2}-y^{2}=63}} right.\\left { {{x-y=3} atop {(x-y)(x+y)=63}} right.\\left { {{x-y=3} atop {3(x+y)=63}} right.\\+left { {{x-y=3} atop {x+y=21}} right.\------\2x=24\\x=12\\y=x-3=12-3=9$

Ответ :(12 , 9)