$$S= { \left(x-1 \right) }^{ 2 } + { \left(x+1 \right) }^{ 2. } ,x= \frac{ 1 }{ \sqrt{ 5 } }$$
$x=\frac{\sqrt{5}}{5}\approx 0.447213595$
$S = \frac{12}{5} = 2\frac{2}{5} = 2.4$
