How do you find the center and radius for # x^2 + y^2 - 8x + 14y + 40 = 0#?
circle centre (4, -7), radius 5
Simple answer: by using algebra and completing the square - TWICE, once for x and once for y.
We're starting with:
So we complete the squares. Will do separately so it's clearer, hopefully
For the x's
For the y's
pop these back into the original, and we get
that's a circle centre (4, -7), radius 5