find the center and the radius

Question

9x^(2)+9y^(2)+42x+84y=-65

Answer 1

9x²+9y²+42x+84y=-65 (divide both sides by 9)

x²+y²+(42/9)x+(84/9)y=-65/9

(x+21/9)²+(y+42/9)²=(21/9)²+(42/9)²-65/9

(x+21/9)²+(y+42/9)²=20

Center: (-21/9, -42/9)

Radius: r=√20=2√5