Question

What is the center and radius of the circle with the given equation? x^2+y^2+8x-4y=-11

Answer 1

To identify these things, first we need to rearrange the equation so that it looks like this:
\[\Large (x-\color{red}h)^2 + (y-\color{green}k)^2 = \color{blue}r^2\]

Answer 2

I'm not sure what goes where

Answer 3

Right, well, doing this requires a certain skill known as 'completing the square'
Have you heard of it?