Solve by completing the square: 4x^2 - 8x - 8 = 0
a) -2 + sqt. 2, -2 - sqt.2
b) 1 + sqt. 3, 1 - sqt. 3
c) 1 + sqt. 2, 1 - sqt. 2
d) -2 + sqt. 3, -2 - sqt.3