What is the equation of a circle with a center located at (4,-1) and a radius of 9

The equation for a circle with the given information would be (x - 4)^2 + (y + 1)^2 = 81.

This is because the base form of a circle is:

(x - x1)^2 + (y - y1)^2 = r^2

In which, x1 is the x coordinate of the center and y1 is the y coordinate of the center. r is the radius of the circle. So we plug in to those and simplify.

(x - 4)^2 + (y - -1)^2 = 9^2

(x - 4)^2 + (y + 1)^2 = 81

b) 36

step-by-step explanation:

18 times 2 is 36