C(-3,0) and the Radius is R =√21
1) Let's consider this formula x² + 6x +y² = 12. Reminding that the formula of the circle is given by
(x-a)² +(y-b)² =r² Let a, and b the coordinates of the Center of the Circle)
2) So we can write
x² +6x +y² =12 Rewriting it grouping
(x² + 6x) +y²=12 Complete the square, add 9 to both sides
(x²+3x+9) +y²= 12+9
(x+3)²+y²=21
3) So we can state that the Center and the Radius are, comparing it to the General Formula:
C(-3,0) and the Radius is R =√21
