4 A curve has equation \(y = ( 2 x - 1 ) ^ { - 1 } + 2 x\).
- Find \(\frac { \mathrm { d } y } { \mathrm {~d} x }\) and \(\frac { \mathrm { d } ^ { 2 } y } { \mathrm {~d} x ^ { 2 } }\).
- Find the \(x\)-coordinates of the stationary points and, showing all necessary working, determine the nature of each stationary point.