Which is the equation of a circle centered at the origin with radius 20?

x^2 + y^2 = 400

Step-by-step explanation:

The equation for a circle is

(x-h)^2 + (y-k)^2 = r^2

where (h,k) is the center and r is the radius

(x-0)^2 + (y-0)^2 = 20^2

x^2 + y^2 = 400

the number of the people going.

step-by-step explanation:

the cost to buy one movie ticket is $7. if the total cost for the movie is a function of how many people go, then the input is : the number of the people going.

no i do not : ( what is it?