Question

Решите систему уравнений
x^2-y^2=8
2x-2y=-4

Answer 1

x^2-y^2=8
2x-2y=-4

2x=-4+2y
x=(-4+2y)/2

((-4+2y)/2)^2-y^2=8
(4y^2-16y+16)/4)-y^2=8
домножим на 4
4у^2-16у+16-4у^2=32
-16y-16=0
16y=-16
y=-1

x^2-y^2=8
x^2=8+y^2
x^2=9
x=3