You are not logged in.
Pages: 1
x^2 + y^2 + 8x + 8 = 0 find the radius and center
Offline
All circles can be described by the equation (x - a)^2 + (y - b)^2 = r^2, where the center is located at (a, b) and has a radius of r. What you have to do is work with your equation to get it to fit into the general equation I just gave you.
Figuring out b is simple. Since there is no y term you know that b has to be 0.
Finding a is only slightly more difficult. Expanding the expression (x - a)^2 gives us x^2 - 2ax + a^2. Our x term is 8x, so we know that 8x = -2ax, which gives us a = -4.
We're not quite done with x yet, since (x + 4)^2 = x^2 + 8x + 16, but we don't have a term of 16. We do have an 8, so what we can do is add 8 to both sides. This gives us (x + 4)^2 + (y - 0)^2 = 8, and your work is done.
Wrap it in bacon
Offline
Pages: 1