Răspuns :
4x^2 - 4x - 4x + 4 = 0
4x(x - 1) - 4(x - 1) = 0
(4x - 4) (x - 1) = 0
4 (x - 1) ( x - 1) = 0
x = 1, 1
4x(x - 1) - 4(x - 1) = 0
(4x - 4) (x - 1) = 0
4 (x - 1) ( x - 1) = 0
x = 1, 1