Help me which expression is undefined?
-4+0/ 8 (its a dividing btw)
0 divided by 11
- 0/2
3/ (6-6)

3/(6-6) is undefined. any expression divided by 0 is undefined. in this case when you subtract 6 from 6, u get 0 which makes the expression undefined! hope this helps

X^2 - 4x +(4/2^2) + y^2 + 8y + (8/2^2) = -4 + (4/2^2) + (8/2^2)(x + 2)^2 + (y + 4)^2 = -4 + 4 + 16your center is (-2, -4) and the radius is the sqrt of -4 + 4 + 16 which is 4