(i) To express \(2x^2 - 12x + 13\) in the form \(a(x + b)^2 + c\), complete the square:
\(2x^2 - 12x + 13 = 2(x^2 - 6x) + 13\)
\(= 2((x-3)^2 - 9) + 13\)
\(= 2(x-3)^2 - 18 + 13\)
\(= 2(x-3)^2 - 5\)
Thus, \(a = 2, b = -3, c = -5\).
(ii) For \(f(x)\) to be one-one, the derivative \(f'(x) = 4x - 12\) must be non-negative for \(x \geq k\). Solving \(4x - 12 \geq 0\) gives \(x \geq 3\). Therefore, the smallest possible value of \(k\) is 3.
(iii) With \(k = 7\), the minimum value of \(f(x)\) is \(f(7)\):
\(f(7) = 2(7)^2 - 12(7) + 13 = 98 - 84 + 13 = 27\)
Thus, the range of \(f\) is \(y \geq 27\).
(iv) To find \(f^{-1}(x)\), start with \(y = 2(x-3)^2 - 5\) and solve for \(x\):
\(2(x-3)^2 = y + 5\)
\((x-3)^2 = \frac{1}{2}(y + 5)\)
\(x-3 = \pm \sqrt{\frac{1}{2}(y + 5)}\)
Since \(x \geq 7\), choose the positive root:
\(x = 3 + \sqrt{\frac{1}{2}(y + 5)}\)
Thus, \(f^{-1}(x) = 3 + \sqrt{\frac{1}{2}(x + 5)}\) for \(x \geq 27\).