Question

Решить систему уравнений: х^2-ху+у^2=63 х-у=-3

Answer 1

Х^2-ху+у^2=63
х-у=-3
==================
(-3+y)^2-(-3+y)y + y^2=63
x=-3+y
==================
(-3+y) *((-3+y) - y) + y^2=63
(-3+y)(-3+y-y)+y^2=63
(-3+y)(-3)+y^2=63
9-3y+y^2-63= 0 
-54-3y+y^2 = 0 
y^2-3y-54 = 0
D=(-3)^2 - 4*(-54) = 9 + 216 = 225
√225 = 15
y1 = (-3+15)/2 = 12/2 = 6 
y2=(-3-15)/2 = -9
=================
x1 = -3 + 6 = 3
x2 = -3+(-9) = -12
Ответ: (3;6) (-12;-9)