Question

What is the center and radius of the circle with the given equation? (x-1)^2+(y+1)^2=4.

Answer 1

http://www.mathwarehouse.com/geometry/circle/images/equation-of-circle/general-formula-equation-of-circle.png

Answer 2

so would it be center (-1,1) radius 4? :)

Answer 3

let's rewrite yours a bit
$$\bf (x-h)^2+(y-k)^2=r^2\\
(x-1)^2+(y+1)^2=4 \implies
(x-(\color{blue}{+1}))^2+(y-(\color{blue}{-1}))^2=2^2
$$

Answer 4

okay, so it would be 1,-1 with a radius of four?

Answer 5

\(\bf r^2 = 4\\
r = \sqrt{4} = 2\)

Answer 6

I didnt know we were supposed to square it back, thank you so much!

Answer 7

yw