x^4 + 1/x^4 - 2 in the form of factors is : 1. (x -1/x)^2(x + 1/x + 1)^2 2. (x - 1/x)^2(x + 1/x)^2 3. (x + 1/x)^2(x - 1/x + 1)^2 4. (x + 1/x)^2(x + 1/x - 1)^2