Question

Write the standard equation of the circle,

Answer 1

The center of the circle is at (2,-1) and has radius of 3.

The equation of a circle is:

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

where (h,k) is the center of the circle , and r = radius of the circle.

So, in our problem, the equation has to be

(x - 2)^ + (y + 1)^2 = 9 (3^2 = 9)

Answer 2

In standard form, it would be:

x^2 - 4x + y^2 + 2y - 4 = 0

Answer 3

That's not an option :/
The options are

(x + 2)2 + (y - 1)2 = 9
(x - 2)2 + (y + 1)2 = 3
(x - 2)2 + (y + 1)2 = 9
(x - 1)2 + (y + 2)2 = 3