5 The curve \(C\) has equation
$$y ^ { 2 } + ( x y + 1 ) ^ { 2 } = 5$$
- Show that, at the point \(( 1,1 )\) on \(C , \frac { \mathrm { dy } } { \mathrm { dx } } = - \frac { 2 } { 3 }\).
- Find the value of \(\frac { d ^ { 2 } y } { d x ^ { 2 } }\) at the point \(( 1,1 )\).