The curve \(C\) with equation \(y = \text{f}(x)\) is such that
$$\frac{\text{d}y}{\text{d}x} = 3x^2 + 4x + k,$$
where \(k\) is a constant.
Given that \(C\) passes through the points \((0, -2)\) and \((2, 18)\),
- show that \(k = 2\) and find an equation for \(C\), [7]
- show that the line with equation \(y = x - 2\) is a tangent to \(C\) and find the coordinates of the point of contact. [5]