Question

Find radius and center

Answer 1

(0,0) and r=3

Explanation:

To find the radius and center rewrite the equation in vertex form
`(x-h)^2+(y-k)^2 = r^2`.

First move x and y to the other side so they have positive signs. Then move 9 across to the other side too.

`-9 = -y^2 -x^2\\x^2 + y^2 -9 = 0\\x^2 + y^2 = 9`

Here you can see there is no h or k meaning h=0 and k=0. The radius is the square root of 9 which is 3.