Question

Need help #14
The center of the circle is (0,-8). The radius is 9.

Answer 1

C and D

Explanation:

The equation of a circle is

(x - h)² + (y - k)² = r² where (h,k) is the center, and r is the radius

Plug in what you were given, and simplify...

(x - 0)² + (y - (-8))² = 9²

x² + (y + 8)² = 81

This is answer C.

We can get answer D by foiling out (y + 8)² and simpligying...

x² + y² + 16y + 64 = 81

x² + y² + 16y = 17 (subtract 64 from both sides)

Answer 2

X^2+ (y+8)^2 = 81.....this is C.
X^2 + y^2 + 16y +64=81 so x^2 + y^2 + 16y = 17.....this is D.

So I’d say C and D are correct