Chapter 13 - Section 13.3 - Solving Nonlinear Systems of Equations - Exercise Set - Page 948: 21

$(0, -1)$

$x^2+y^2=1$ $x^2+(y+3)^2 =4$ $x^2+y^2=1$ $x^2+y^2-y^2=1-y^2$ $x^2=1-y^2$ $x^2+(y+3)^2 =4$ $(1-y^2)+ (y+3)^2 =4$ $1-y^2+(y*y+3*y+3*y+3*3)=4$ $1-y^2+y^2+3y+3y+9=4$ $1+6y+9=4$ $10+6y=4$ $10+6y-10=4-10$ $6y=-6$ $6y/6=-6/6$ $y=-1$ $x^2+y^2=1$ $x^2+(-1)^2=1$ $x^2+1=1$ $x^2+1-1=1-1$ $x^2=0$ $\sqrt {x^2} = \sqrt 0$ $x=0$