7+9+11...+2013-5-7-9-...2011

If you would like to calculate 7 + 9 + 11 + ... + 2011 + 2013 - 5 - 7 - 9 - 11 - ... - 2011, you can do this using the following steps:

7 + 9 + 11 + ... + 2011 + 2013 - 5 - 7 - 9 - 11 - ... - 2011 = (7 + 9 + 11 + ... + 2011) + 2013 - 5 + (- 7 - 9 - 11 - ... - 2011) = 2013 - 5 = 2008

The correct result is 2008.

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