The function f : ↦ x² −4x + k is defined for the domain x ≥ p , where k and p are constants.

i. Express f(x) in the form (x + a)² + b + k, where a and b are constants.

ii. State the range of f in terms of k.

iii. State the smallest value of p for which f is one-one.

iv. For the value of p found in part iii, find an expression for f⁻¹(x) and state the domain of f⁻¹, giving your answer in terms of k.