x^2+2x+y^2=16
x+y=16 => y=2-x
x^2+2x+(2-x)^2=16
x^2+2x+4-4x+x^2=16
2x^2-2x-12=0
x^2-x-6=0
D=b^2-4ac=1-4*1(-6)=25
x1,2=(-b±sqrt(D))/2a
x1=(1+5)/2=3
x2=(1-5)/2=-2
При x1=3 y1=2-3=-1
При x2=-2 y2=2-(-2)=4
x^2+2x+y^2=16
x+y=16 => y=2-x
x^2+2x+(2-x)^2=16
x^2+2x+4-4x+x^2=16
2x^2-2x-12=0
x^2-x-6=0
D=b^2-4ac=1-4*1(-6)=25
x1,2=(-b±sqrt(D))/2a
x1=(1+5)/2=3
x2=(1-5)/2=-2
При x1=3 y1=2-3=-1
При x2=-2 y2=2-(-2)=4