Unfortunately, the browser used by Answers.com for posting questions is incapable of accepting mathematical symbols. This means that we cannot see the mathematically critical parts of the question. Assuming that the equation is
4 - 4y + y^2 = 0, the two values of y are
-2-2*sqrt(2) = -4.8284, approx, and
-2+2*sqrt(2) = 0.8284, approx.