Past exam of the geometry course of the University of Oxford / 2011 / 5 / d / Solution

On the parameter, the two transformations are $S(\lambda )=1/\lambda$ and $T(\lambda )=1-\lambda$. Their compositions yieldEvery step lifts to an invertible projective transformation of the corresponding cubic curves. Therefore all six parameter values give isomorphic curves. Some values coincide for special $\lambda$; this does not affect the conclusion.