Answer:
Center: 
Radius: 
Step-by-step explanation:
-According to the following equation, the center would be
, because the center is known as
from the equation of a circle. To find the radius, you would only need to square root the simplified radius from the following the equation and you would get the radius 15:
The equation of a circle:

The following equation:

Center:
Radius: 
Practice, practice & practice.
Answer:
Step-by-step explanation:
Proportional.
y = 9x
The constant is 9