Question

x²+y²=5; x-y=1 в фигурных скобках

Answer 1

x^2+y^2=5
x-y=1

x=y+1

(y+1)^2+y^2=5
(y+1)(y+1)=y^2+y+y+1=y^2+2y+1
y^2+2y+1+y^2=5
2y^2+2y-4=0 |:2
y^2+y-2=0
D=1-4*(-2)*1=9
y_{1,2}=(-1+/-3)/2
y_1 = 1 ; y_2 = -2
x=1+1
x=2
x=-2+1
x=-1
(y=1;x=2) (y=-2; x = -1)