Question 962416
x^2 +4kx -k = 0
x^2 +4kx = k
x^2 +4kx +4k^2 = k +4k^2
(x +2k)^2 = k +4k^2
x+2k = sqrt(k+4k^2)
x+2k = sqrt(k(1+4k))
x+2k = sqrt(k) * sqrt(1+4k)
x = sqrt(k) * sqrt(1+4k) - 2k