Решить систему:
x^2-xy+y^2=63
x-y=-3

x^2-2xy+y^2+xy=63 (x-y)^2+xy=63 (-3)^2+xy=63 xy=63-9=54 x-y=-3 x=y+3 y(y+3)=54 y^2+3y-54=0 D=3^2-4*(-54)=9+216=225 y=(-3+15)/2=6 или y=(-3-15)/2=-9 x=y+3=6+3=9 x=y+3=-9+3=-6 Ответ: x=9 y=6; x=-6 y=-9