Find the value of k, if x - 1 is a factor of p(x) in each of the following cases: (i) p(x) = x^3 + x + k (ii) p(x) = 2x^3 + kx + √2 (iii) p(x) = kx^3 - √2 x + 1 (iv) p(x) = kx^2 - 3x + k